Browsing posts in: Nutrition

The biochemistry of weight and nutrition–Part #1: Carbohydrates

Back in May of 2017, I started a journey to learn more about how the biochemistry of weight works; how our bodies metabolism carbohydrates, protein, and fats, and how that influences our weight.

When I started, I had a pretty simplistic view of how our bodies work.  I’m still only starting to have a functional understanding of the underlying biochemistry, but what I’ve found is that our bodies are very complex and fascinating systems shaped by the environment in which we evolved, and that if you understand the underlying biochemistry, things make more sense.

So… This is my attempt to present a simplified view of the underlying biochemistry. If you want to learn more, I recommend starting with a copy of “Mark’s Basic Medical Biochemistry”, but I’ll caution you that the section on carbohydrate metabolism alone is around 84 pages, so it’s pretty dense. If you want a slightly lighter approach, you can try “Mark’s Essentials of Medical Biochemistry”, which is a bit shorter. In either case, read them and then find some YouTube videos that talk about the subject, and iterate on this process a few times.

A few basic principles:

Our bodies are adaptive systems

If you’ve ever trained for an athletic event, you know that when you start training it’s really hard, but it gets easier over time as your body adapts, by making physical changes to your body. Our bodies also have an adaptive response to the kinds of foods that we eat, and that response can take time.

Our bodies try to be energy efficient

We evolved in an environment where food was not always plentiful, and our bodies generally attempt to be efficient and not waste any food calories.

Reactions to diets vary significantly between individuals

Genetics, age, sex, medical history, and activity level are all significant when considering how a specific person reacts to a specific diet. Or, to put it another way, one person may be able to remain healthy on a diet that would make somebody else very sick.


Carbs

I’m starting with carbs because their role is central to how your body reacts to the food that you eat. I’m going to talk about the different kinds of carbohydrates, how they are digested/absorbed, and how they are metabolized (used) by our bodies.

The nomenclature around carbs is a bit confusing, but they break into four broad classes:

Simple Sugars (aka “monosaccharides”)

The simple sugars are the ones that aren’t broken down by our digestive systems to something simpler. Most people are familiar with fructose and glucose, and there is also galactose, which I’ll discuss more in a bit. There are also some rarer sugars and sugar alcohols that I’m ignoring for now.

Compound Sugars (aka “Disaccharides”)

“Di” meaning “two”, these are sugars that are compounds of two simple sugars.

  • Sucrose (aka “table sugar”) is a compound of one molecule of glucose and one molecule of fructose
  • Lactose (aka “milk sugar”) is a compound of one molecule of glucose and one molecule of galactose
  • Maltose (aka “malt sugar”) is a compound of two molecules of glucose.
  • The much maligned High Fructose Corn Syrup is not a compound sugar, but a mixture of simple sugars. It comes in different fructose/glucose ratios, with the most common one being 55% fructose, so it’s similar to sucrose in its underlying composition and effect on the body.

    Complex carbohydrates (aka “Oligosaccharides” and “Polysaccharides”)

    All of the complex carbohydrates are chains of simple sugars hooked together (“oligo” means “a few”, and “poly” means “a lot”).

    In this class we have ingredients like maltodextrin (a small chain of glucose molecules), or starches (big chains of glucose molecules).

    Cooked starches are easily broken down into their simple sugars by our digestion. Some raw starches – also known as “resistant starches” – are poorly digested in the small intestine, and digested by bacteria in the large intestine and converted to short-chain fatty acids, which are absorbed. I would call them “starches that don’t act like more familiar starches”.

    Undigestible carbohydrates (aka “fiber”)

    Humans don’t have the digestive equipment to extract energy from carbohydrates like cellulose, so they just pass through our systems.

    Carbohydrate absorption

    With the exception of resistant starches and fiber, all of the carbohydrates are broken down to glucose, fructose, or galactose by the digestive system before they enter the bloodstream. The rate at which they enter the bloodstream depends upon a number of factors. A refined sugar is more accessible than one that is bound up within fiber in a food, so it is absorbed faster. A sugar that is by itself is more accessible than one that is mixed in with fat and protein. Different sugars have different transport mechanisms to get them from the digestive system into the blood stream and therefore have different rates of absorption.

    But at the bottom, it’s glucose, fructose, or galactose. The sugars that you get from eating an apple aren’t chemically any different from those you get from a can of Coke. The two foods – if you can call a can of coke “food” – differ in the total amount of carbs, the ratios of different types of carbs, the rate at which the carbs are absorbed, and the non-sugar ingredients, but they both end up as simple sugars in your system.

    Complex carbohydrates also aren’t inherently different than simple sugars; they may not taste sweet, but they end up as simple sugars (typically glucose) when they are absorbed.

    Carbohydrate Metabolism

    Metabolism is all about what happens to the nutrient after it gets into our bloodstream. It turns out that the different simple sugars are processed very differently.

    I’m going to start with glucose metabolism.

    Glucose metabolism

    The amount of glucose in our blood – our blood glucose (or blood sugar) level – is one of the most important values for us as living organisms. Too little (aka “hypoglycemia”), and we get hungry, headachy, sleepy, confused, or worse. Too much (aka “hyperglycemia”), and we have other issues; a lot of our body’s systems do not work well with too little or too much blood glucose.

    Our bodies therefore have a system to keep blood sugar constant, and this is a high priority system; it is fair to say that “keep blood glucose within range” is Job One for our regulatory systems.

    Let’s say we ate a small plain bagel or drank a can of Coke. That’s going to send somewhere around 30 grams of glucose into our system. That is over 7 times the amount of glucose we normally have in our bloodstream, so we need a place to put the excess glucose, and biochemical system to pull the glucose out of the blood and put it in that storage place.

    Storing Glucose

    There are two different methods of storing glucose in our bodies.

    We can store it in our liver or our muscles as glycogen, a compound that is very close to glucose chemically. Glycogen is a little like a starch; it’s just a bunch of glucose molecules surrounding a protein known as glycogenin, and it’s quick and easy to get the glucose back out. The storage for glycogen is fairly limited; the muscles can store about 400 grams, and the liver can store about 100 grams, or 500 grams / 2000 calories total. If you have ever “hit the wall” or “bonked” during extended exercise, you’ve experienced what happens when you run out of liver glycogen.

    If your liver and muscle glycogen stores are already full, the excess glucose out of the blood needs to go somewhere else.

    There is only one other place for storing the excess energy that the glucose represents, and that is our fat stores. We tend to think of sugars and fats to be very different things – one is white and crystalline, and the other is oily or greasy – but they are both molecules made from carbon, oxygen, and hydrogen. The liver and fat cells can take in the excess glucose and convert it to fat, which is stored in our fat cells.

    The biochemistry to do this is built on a hormone that we have all heard of, insulin. When blood sugar is high, the pancreas releases insulin, which has 3 main effects our system:

    1. The muscles and liver increase their absorption of glucose to store as glycogen (assuming there is room to store it).
    2. The body turns off fat burning, so that current energy use will help use up glucose.
    3. The fat cells increase their absorption of glucose to store as fat.

    The speed at which glucose can be stored depends on where it is being stored; storing it as glycogen is quick, while storing it as fat is slow. Here’s an interesting chart from a study:

    Image result for insulin resistance glucose levels

    The subjects in this study had slept overnight, which had burned some of the glycogen in their stores. They then gave them one of three breakfasts:

    • A can of Coke
    • A service of instant oatmeal
    • 2 poached eggs.

    Both the Coke and the oatmeal have a lot of carbs, and the eggs have almost none.

    Then, they fed them a *second* breakfast of oatmeal – a lot of carbs – and measured their blood sugar over time.

    What they found was that if the first breakfast was eggs, the second breakfast had little effect on their blood glucose, because all of those carbs went straight back into filling up the glycogen stores. If the first breakfast had carbs, they had mostly refilled the glycogen stores already, and it therefore took quite a while to get the blood sugar back to normal. Which means that much of the second breakfast was stored as fat.

    These charts showed what happened with a healthy person – one that we would call “insulin sensitive”. The blood glucose gets back to normal.

    For some people, that doesn’t happen. There are different theories as to why it doesn’t happen; one is that the glycogen stores just get full, one is that the fat and liver cells can’t do the conversion to fat well, and there are others. Regardless, their glucose-absorbing cells become resistant to the effects of insulin, which we call “insulin resistance”. The first reaction of our bodies is to try harder by using more insulin, but this is an arms race that can eventually lead to problems in insulin production. Many people progress from insulin resistance to type II diabetes and metabolic syndrome.

    I want to stress here that insulin resistance and type II diabetes are about the abilities of our bodies to regulate blood glucose levels, they are not about weight. It is true that people who carry a lot of extra weight are more likely to have blood glucose issues, but there are obese people who have good blood glucose control, and – perhaps more surprisingly – there are thin or normal weight people who have insulin or type II diabetes. They have bodies that are not good at converting excess glucose to fat.

    That is why testing for blood glucose over time is important. Unfortunately, testing for blood glucose every day is intrusive and not something you can use with the general population, so for a long time all that was used was the blood glucose measured at one time, which is not a good predictor.

    Then a weird bit of biochemistry came to the rescue. It turns out that in our red blood cells, the hemoglobin that transports oxygen can become glycated – it can have a glucose molecule attached to it. The chance of that happening depends on the average amount of glucose in the blood; if you have a low average blood glucose, few of your hemoglobin molecules will be glycated, while if you have high average glucose, more will be glycated.

    And, it turns out that when red blood cells die, we can look at the hemoglobin and see how much was glycated, and therefore have a good idea the overall glucose levels, as a weighted average for the past few months. 

    The test to do this generates a value known as HbA1c, or simply A1c, and it’s the prime diagnostic measure for insulin resistance and type II diabetes.

    Low blood glucose

    Thankfully, this is a lot simpler.

    The reaction to low blood glucose is somewhat the opposite to high blood glucose. It is mediated by a hormone released by the pancreas known as glucagon, which has roughly the opposite effects as insulin:

  • The glycogen stored in the liver is converted back into glucose and released into the bloodstream (the glycogen in muscles can only be used locally; it cannot be released back into the bloodstream).
  • The body encourages the release and burning of fatty acids rather than carbohydrates.
  • If that is enough to raise the blood glucose, that everybody is happy. If the low blood glucose continues for longer – say for a few days – the body switches over to an alternate fueling approach known as “ketosis”, which involves the following changes:

  • The liver starts producing what are known as “ketone bodies”, which you can think of a glucose substitute for some of the body tissues; the brain can largely use ketone bodies for fuel, as can some muscles.
  • The muscle switch to burning more fat and less carbohydrate to produce energy. Like any exercise adaptation, this occurs over time.
  • The liver starts producing glucose from whatever it has lying around; it might be glycerol from fat metabolism or excess protein, or both. This is known as “gluconeogenesis”.
  • Together the switch to ketone bodies and the creation of new glucose is enough for the body to function normally without eating carbs. Adapting to this takes a couple of weeks for most individuals, though adapting to burn more fat during exercise takes much longer.

    Ketosis is a response whenever carbs are severely limited, whether it be a fast or a ketogenic diet. Ketosis is not an all-or-nothing response; a person on a relatively low-carb diet might be in ketosis overnight when their carb reserves get low and then switch out of it during the day when carbs are more available.

    And that is the story on glucose.

    Galactose metabolism

    Galactose metabolism is pretty much like glucose metabolism, except a trip to the liver is required to break the galactose molecule apart into two glucose molecules, which are either used by the liver or released into the bloodstream.

    Fructose metabolism

    Our body cannot metabolize fructose directly, so first it has to take a trip to the liver to be converted to something that is more useful.

    It ends up as one of three things:

  • Glucose, which is stored in the liver, converted to fat by the liver, or released into the blood stream.
  • Lactate, which can be used by other tissues
  • Triglycerides (ie fat).
  • There is considerable discussion around what the proportions are between those three products and what controls those proportions.

    Some researchers theorize that in some cases, the triglyceride pathway is especially active and that leads to the accumulation of fat in the liver and a condition known as Non Alcoholic Fatty Liver Disease (NAFLD). My limited understanding says that we don’t have definitive evidence on this, but we do know that alcohol is metabolized into fat in the liver and the accumulation of fat causes alcoholic fatty liver disease, and since fructose can also be metabolized into fat in the liver, it’s an interesting hypothesis.

    Futures

    That’s all for carbohydrates.

    Upcoming, we have fat and protein to talk about, and probably a discussion around energy partitioning, which is how our bodies decide what fuel to burn.


    Down 20?

    (Authors Note: This is the fourth time I’ve tried to write something like this, but it kept getting *way* too long and detailed. I’ve kept it simple this time, but that means I’ve left out a lot of details, some of which are surely important. So ask if you have questions…)

    It started with the candy dish…

    Early last spring, due to show reshuffling, my team ended up in the same room as our admin – which was fine – and in the same room as the group candy supply – which was not.

    It was a bit better than my previous team – which maintained what was officially known as “the candy wall” – but the problem was that the candy dish was at the entrance of my room, so was really easy to come back from lunch, grab a few “fun size” pieces, and eat them at my desk. There’s some interesting research in psychology that says that one of the best ways to get adherence is through random rewards, and our candy dish implementation had that; you might not really be hungry for a Reeses ™ peanut butter cup, but if you see one, you better grab it before somebody else does.

    The whole “work food” culture is pretty horrible when you think about it.

    I am lucky enough to have good genetics when it comes to keeping a decent weight, but the extra candy bumped me up from my long-term “fighting” weight of 173 to 178, and I was feeling really tired and crappy in the afternoons. The first did not bode well for the upcoming cycling season, and the second did not bode well in general.

    At the time, I was on a low-fat diet, which is the kind of diet they tell you to be on. And I’d been doing a bunch of reading about glycemic index and glycemic load, and wondered if that was having an effect. Clearly, the candy was high glycemic index, but was there something in my lunches that was contributing to me craving candy?

    So, I started an experiment. Instead of the sandwiches that I ate at lunch 3 days a week (because they were cheap) and the burritos that I ate the other two (because burritos), I switched to salads with meat three days, and burrito bowls without the rice and tortillas the other days (because burritos).

    It was a pretty simple change, but it had a pretty immediate impact; I still habitually wanted candy (because candy), but I didn’t crave it as much, and I could cut down how much I ate. And I felt much better in the afternoons, which was good, but did not convert them to an endless series of rainbows and unicorns (a guy can dream, right?).

    Anyway, that led to a whole lot of research into nutrition, which led to research into biochemistry, watching a few lectures, and reading a lot of clinical research.

    But I started by trying to answer a question that had always confused me:

    Why is it so damn hard for many endurance athletes to lose weight?

    Some of the cyclists I know are very thin and light, but I know others – many that ride a *lot* more miles than I did – who carried maybe 40 pounds more than they would like to. I knew what worked for me – making sure I controlled my blood sugar well after long rides – but that still required a fair bit of discipline to get me to light, and I never got to “cycling light” – that weight where your cycling friends are annoyed at how little you weigh. That was true of most cyclists I knew. My trust power meter said that I was easily burning 4000 calories per week.

    Why wasn’t all of that exercise translating to weight loss?

    Looking at the clinical studies about exercise and weight loss, we see mixed results. Aerobic exercise works in controlled situations – where the amount of food is controlled – but doesn’t work well where people choose what they eat. There are two hypotheses for what is going on; the simple one is that people are hungry and just eat the calories back; the more troubling (and luckily, probably rarer) one is that exercise under caloric restriction can reduce the base metabolic rate for some people.

    To lose weight, eat fewer calories or burn more

    This has been the mantra for weight control for over 40 years, and it’s what I used to believe. It’s simple to understand, but  doesn’t work very well in practice.

    The problem is that it considers all calories to be the same. But when we are talking about body weight, we don’t want to lose weight, what we really want to do is to lose *fat*. So, let’s recast the statement:

    To lose weight, live in a way that minimizes the amount of energy that is put into your fat stores, and maximizes the amount of energy that is pulled out of your fat stores.

    So, I started looking more closely at how fat accumulation works in humans – what drives calories into fat stores, and what pulls calories out of fat stores.

    I originally had a long and technical discussion on what controls energy partitioning – where the energy to run your body comes from – but I am unable to make such a discussion brief, so here’s the simplified version:

    1. The amount of fat you burn during day to day living is tied directly to the percentage of carbs that you eat. Eat a lot of carbs, burn a little fat; eat a few carbs, burn a lot of fat.

    2. The amount of fat you burn during exercise is tied both to the kind of diet you eat and your energy state when you exercise.

    The key point is that both of these are adaptable behavior; our bodies can adapt (mostly) to different mixes.

    The result of this is that two riders of equal fitness can go on the same ride, both burn 1000 calories, and burn *vastly* different amounts of fat. If you want to look at some pretty graphs that illustrate this, go read this article and this article from CyclingTips.com.

    Back to the experiment…

    Back in real life, I expanded my experiment a bit. My breakfast went from a big-ole bowl of cereal with a lot of milk to a small bowl with minimal milk and a hard-boiled egg. My dinners lost a few of their carbs.

    And I was down about 5 pounds, back to the weight that I wanted, with just some small changes.

    At this point, I really didn’t have many carbs in my base diet – and they were increasingly low-GI carbs – but I was still using Skratch on my rides, and I was still using Endurox after my rides; following my traditional fueling strategy.

    So…

    I forgot to mention another motivation that got me playing around with diet. My on-bike fueling strategy did not work very well. Thankfully, I rarely got the “GI distress” that some people do, but on longer rides I know that I’m going to get some stomach pain from the skratch, and I’m going to have energy issues. That makes rides like RAMROD a bit of a crap shoot; at best I felt sort of blah, but generally I felt a few rungs below blah.  

    The next experiment was obvious: I put the Skratch in the back of the cupboard, and started filling my bottles with water. I put some cheez-its (carbs + fat + protein) in ziploc in my pocket, added a packet of sport beans just in case, and I started riding.

    And that mostly worked. I felt a little under on power, but it was early season and I’m under on power then anyway. I sometimes supplemented a bit with the aforementioned cheez-its in the middle of the ride.

    About this point, I weighed myself, and the scale said 169. I checked another scale to be sure. I hadn’t been this light in 20 years, not even in 2005 when I rode *way* more miles I ride these days. And I was eating what I thought was a lot of food.

    Hmm…

    Somewhere in here, I came across a post by noted cycling coach Joe Friel in which he talked about how he got back down to his “racing weight”, which aligned well with the research I had been doing, the biochemistry I learned, and my experimental results.

    And I thought, “What the hell, let’s see where this thing ends up…”

    Heresy

    I own a copy of “food for fitness”, and a copy of “the feedzone cookbook”. I’ve read all the recommended diets for athletes, and they all recommend a diet high in complex carbs – something like 60 or 65% of calories.

    I decided to go full keto, and see what happened. That means <50grams of carbs per day (though I never actually counted), quite a bit of protein, and more fat. Since I had eased myself into a lower carb diet, the transition was pretty easy (this is not the case for a lot of people), and about a week later, I headed out on Saturday morning for a nice 45 mile ride.

    The first 45 minutes was great; I felt strong, had good power. And then it happened; over the space of about 15 minutes, I ran out of carbs.

    If you’ve bonked, you know what this is like, but this time it was different. I actually felt okay, my brain was fairly clear. I just lost all ability to put power down. You know the Tour de France rides where the guy’s bike breaks and he picks it up and throws it into the bushes? I was close to that. I cut the ride short, could barely push 150 watts the rest of the way home, and regrouped.

    After talking with a few people and doing some more research, I realized that while I was pretty fat adapted for regular life, I was not fully adapted for cycling. So, I kept at it. I did Tour de Blast (6000+ feet of up over 80 miles), felt good at some points and awful at others, bad enough I had my wife pick me up at 70 miles. But the overall trend was positive; I could do my Tue/Thu night rides (35 miles, 2000’ of up) *easily* on just water and feel good at the end. And my high-end power was just fine; one night I out-sprinted one of our race-team guys and did over 1000 watts for about 9 seconds, which is pretty decent for me. The only point of concern I have is the high aerobic range; I don’t think I quite have the pep I used to have there, but give that I made this change right at the beginning of the season (stupid) and didn’t do the kind of high-intensity training I would usually do (lazy), I don’t know how much is a dietary effect and how much is just a lack of training.

    And then finally, near the end of the summer, I did my own supremely stupid ride, Sufferin’ Summits. 9500’ of climbing over 55 miles.

    I did it fasted, and over the 5 hours it took (did I say it was hilly?), I had two servings of a really cool time-release glucose called SuperStarch – about 280 calories total, a bottle of diet coke, and about 14 cheez-its. After dragging myself up the worst hills I know of in the area, I finished the ride.

    And I could have kept going. Honestly, I felt pretty good.

    During the weeks before the ride, my weight continued to drop, and finally the numbers clicked over to 158, which is pretty much where I am right now. I lost two inches off my waist (34 –> 32, my college size), and I lost a ton of subcutaneous fat.  I have a tiny bit of fat remaining around my waist, and I think this spring I might see if I can drop down to 153-155 or so. From what I can tell I *mostly* preserved muscle mass, but since cyclists tend to have the upper bodies of 80-year-old French grandmothers, I have been spending a bit of time in the weight room.

    So that’s the story. Down an honest 20 pounds over 4 months.

    Guidance

    I went as far as I could – heresy, right? – to see what would happen, but there are a lot of variants of low carb. Some athletes do less strict diet variants like Paleo, Primal, or slow carb. Many aim for a higher level of carbs; something like 100 grams per day. A few are very strict on carbs during training but carefully use gels and other simple sugars during events. Some do a complex cyclic protocol. Some do it as a weight reduction approach during the off season and switch back to a moderate carb diet during the bulk of the season.

    There are a lot of options, which is good, because there isn’t a lot of research in this area yet (and I’m not sure who would pay for research; certainly not the exercise drink folks).

    As I said at the beginning, if you have questions, please ask me.


    From carb-optimized to fat-optimized: a brief summary

    (I’ve written this from a cycling perspective, but I think the basic idea – going from a carb-optimized metabolism to a fat-optimized one – has a broader application).

    For those who don’t know me, I’m a fairly typical recreational cyclist; in season I’m riding 3 times a week, generally anywhere from 75 miles to 120 miles, with a few goal events (I tend toward hilly events, such as RAMROD, Passport 2 Pain, and my very own Sufferin’ Summits).

    Over the years, I’ve mostly used a low-fat diet; one focusing on low-GI carbs (brown rice, whole-wheat bread, etc.) for my normal diet, and one with high-GI carbs before, during, and after my rides.

    That has worked okay, more or less, with a few issues:

  • My stomach is often not very happy with a slug of sugar-based nutrition drink during a ride (I have fructose intolerance, which may be part of it).
  • I generally feel tired when I get to about 4 hours on the bike. Not leg tired, but just a general overall feeling of fatigue.
  • I have a really hard time not snacking between meals. This was not helped by having candy readily available at work, but even without that, I still had a hard time not snacking.
  • I also had a related problem. I ski and teach skiing during the winter, which means that I have no weekend time for rides from December through mid-March, and a lot of chance to snack after skiing. Those combined with my work snacking, and in early 2016 I was at 178 lbs, about 6 lbs above my traditional adult weight of 172 lbs.

    Some of you may be saying, “that’s not that heavy for an athlete”, and that’s true, but I did not like the trend.

    I read a book on nutrition that had been sitting on my Amazon wish list for a year (reference below), I asked a few cyclists at my company about their experience with a lower carb approach. And I did a lot of research about nutrition and metabolism in general; if you want to talk about insulin, glucagon, ketosis, I can go on for quite a while, and I can also talk a bit about the current state of clinical measurements (HDL, LDL, LDL-P) and their relation to cardiovascular disease.  Oh, and the experience of indigenous people such as the Inuit and what happened when they started to eat a western diet.

    My conclusion was that I was eating quite a few carbs in my diet and not much fat, which meant that my body was going to be optimized towards using carbs as a fuel source. My other conclusion was that eating the carbs was contributing to my snacking, because a) the insulin response to the carbs would tend to drop my blood sugar back down and b) the lack of fat wasn’t making me feel satisfied after a meal.

    So, it was time to experiment. I’m not somebody who likes to make giant changes in my diet all at once, so I focused on lunch, especially at work. Here’s what I was eating before:

    Monday: Burrito day. A whole wheat burrito, black beans, rice, chicken breast, cheese, guac
    Tuesday: A half sandwich; chicken/turkey breast, cheese, lettuce, tomatoes, pickles, mustard
    Wednesday: See Tuesday
    Thursday: Taco salad day. In a tortilla bowl, black beans, rice, chicken breast, lettuce, guac, olives, cheddar cheese
    Friday: See Tuesday

    Just writing that, wow, that’s a lot of carbs. And wow, my cafeteria is boring.

    Here’s what I switched to:

    Monday: Mexican day. Black beans, half chicken & half pork, onions, lettuce, cheese, guac
    Tuesday: “Barbecue day”. Either brisket or a half chicken with cole slaw, and a tiny square of cornbread
    Wednesday: Salad. Greens + tomatoes, cucumbers, peas, kidney beans, red bell pepper, sugar peas, olives, mozarella balls, eggs, and chicken thight. All topped with an oil/balsamic vinegar dressing.
    Thursday: Mexican day repeat
    Friday: Salad repeat

    Gone are tortillas, bread, rice. Added in are more vegetables, and considerably more fat (pork, brisket/whole chicken, chicken thighs, salad dressing)

    The change was surprisingly easy, with the hardest part being changing my perception of fat. And I noticed an immediate effect on how I felt at work; I was less tired in the afternoon and I stopped snacking totally (it did help that the snacks moved out of my room).

    I switched out my sugar-based hydration drink with an electrolyte one (Nuun has bothered my stomach and I don’t like plain water on rides, so I’m using Hammer’s right now), and went on a few rides.

    And hated it. I means, seriously hated it. I was not running out of energy per se, nor did I have much hunger, I just could not put out any power to save my life. I played around with food with different levels of carbs before and during (I still think a carb recovery drink makes a lot of sense after a long ride), and it has gotten better but I don’t think I have that part figured out yet. More about that later.

    That was working well, so attacked my breakfast next, which was a bowl of granola with fruit. I added an egg (sometimes two) in the morning and reduced the granola, and that’s where I am right now. I honestly probably need a bit more fat in the morning but it is so hard to change ingrained habits. I also changed my dinner patterns a little, trying to focus more on the protein/fats and the vegetables and less on the carbs. Also still a work in progress.

    Oh, and for snacks at home, I’m eating cheese, home-made jerky (time to make a new batch…), and a fair bit of nuts. I’ll have some popcorn now and then, and maybe some chips.

    One thing to stress is that, with the exception of paying attention to my snacking habits at work – where I have a “drink a glass of something first before you eat” rule – I’ve put pretty much zero effort into limiting my portion sizes. I just eat what seems decent, and stop when I am done.

    Results:

    My expectations weren’t very high; I would be happy if I got down to my usual weight and felt a little better on the bike.

    What happened is that in about 3.5 months, I lost a full 10 pounds of weight, clocking in at 168 lbs this week. My summer shorts fit nice and loose, and today I pulled on a pair of 501s that I hadn’t worn for about 9 months, and they fit fine.

    On the bike, I’m feeling strong but I feel like I might be missing a bit of my top end. On the other hand, last week I took 33 seconds off of my PR on a 7 minute climb and some of my riding friends say I’m faster, so maybe it’s not as big as I think, or maybe it’s just different. I have definitely felt less tired after a few hours on the bike, and my stomach is much happier on the bike.

    References:

    For a lot of reasons, low-carb is still fairly controversial and a number of sources say that its not healthy and you’ll grow a third arm or something. Much of that is due to the evolution of thought around the role of cholesterol levels in the blood, from “cholesterol = horrible” to “HDL / LDL” to “hey maybe LDL as a measure doesn’t work, how about LDL-P”. Remember that dietary guidelines have a *huge* lag time behind current research, and there is lots of out of date advice out there.

    If you read anything, read a copy of “Why we get fat” by Gary Taubes. He may not have the whole story from a biochemical standpoint, but his overall presentation is very good. If you like lots of details, read his “Good Calories, Bad Calories“, but be prepared to bone up on your biochemistry.

    Joe Friel – author of many training books for endurance athletes – has written some very interesting blog posts about low carb. In “Aging – My Race Weight“, he details an experience very similar to mine. Read “Becoming a better fat burner“. And read the comments on these posts as well.

    If you are looking for research into low carb and performance, there is a decent summary here. Note that most of the investigation has been purely around performance, and the results seem pretty clear that low carb does not increase performance and may take a bit off the top end (perhaps in some people, perhaps in all). What the studies miss are the things that I really care about; if I don’t have to eat as much on the ride, I avoid the stomach issues that I’ve had over the years, I (hope) that I will have less trouble with low energy during the ride, and the obvious performance advantages of less weight.

    If you want more details and/or references, please let me know in the comments.


    Accelerade light recipe

    I’ve used http://www.accelerade.com/mountain berry as a hydration drink for quite some time. It works pretty well, but it has a problem – it’s sweetened mostly with sucrose, which means that it’s quite sweet. They use some citric acid to counter that a bit, but after a couple of hours it gets too sweet to drink.

    Some people dilute it, which makes it less sweet but also reduces the number of calories in a bottle. I prefer to make the existing drink less sweet.

    What we need is a sugar that acts like sucrose but is less sweet. Maltodextrain is a complex carbohydrate – a chain of glucose molecules all hooked together (sometimes known as a glucose polymer), and it breaks down to glucose very easily.

    I get mine from the supplement house:

     

    My current recipe is 2.5 parts Accelerade to 1 part maltodextrin. I did one batch at 2:1 which is another option.

    Recipe:

    3 3/4 cups Accelerade (750 grams)
    2 1/4 cups Maltodextrin (300 grams)
    1 teaspon salt

    Put in a big bowl and mix. This amount will fit in one of the small accelerade containers. The amount of salt is slightly more than what it would normally have – if you want to keep the sodium the same, you need 8/10ths of a teaspoon.

    This also has less protein – instead of the 4:1 ratio, you’re down to something less than that. You could add more whey protein if you wanted.

     


    Diet, hunger, and blood sugar

    My good friend Chris wrote a nice post about nutrition – one which I am very much in agreement with, and I thought I’d use it as a jumping-off-point to put down some thoughts I’ve had for a while.

    One of the problems in talking about this stuff is that there’s a paradox in how you eat as an athlete. Sometimes you should eat really well, and other times you should do the opposite. But I had a thought recently.

    It all revolves around blood sugar. The whole goal of performance diets is to keep a constant blood sugar level, but the way you do it depends on the circumstances.

    It starts with your base diet – what you eat normally. You want to keep your blood sugar constant, which means avoiding the things that will cause your blood sugar to move quickly. Which means refined sugar, flour, rice, etc. – anything that has a high glycemic index.

    If you eat it, your blood sugar goes up really fast, your body releases insulin, and the sugar gets converted to fat and stored. And your blood sugar drops, and you get hungry again. Which is what is behind the “chinese food” syndrome, where you eat a meal with lots of white rice, and then get hungry again a few hours later.

    It’s not quite that simple, however. It turns out that the absorption of carbs – and therefore their effect on blood sugar – is moderated by the presence of other foods. If you have fat, protein, or fiber, it will slow down the spike in blood sugar.

    So, to keep your blood sugar constant and your hunger in check, you want to have some fat, some protein, some fiber, and any carbs of the less-refined variety. If I had to pick a popular diet that’s close to this, I’d pick something like South Beach.

    That will moderate blood sugar normally, but it doesn’t work when we are exercising. During exercise, we are burning carbs in conjunction with fat, and over time – if we exercise long enough – we will totally run out of carbs, leading to the dreaded “bonk”. Even if we don’t totally run out of carbs, we will end up with very depleted carb reserves. Which means, at the end of the ride you’ll be very hungry, and likely to overeat, or at the very least, not eat very well.

    You also may not be able to fill up those carb reserves in time for your next workout.

    So, we need a way to keep your blood sugar up during the workout. If you can do that, not only will your carb reserves last longer, but you will be less hungry at the end of the workout.

    And how can we do that? Well, we could eat more of our normal healthy diet, but that has a few problems. It’s fairly hard to digest, and you probably don’t have enough blood supply to spare from your muscles to send to your stomach to digest. It’s also pretty bulky, and you don’t really need any extra fat during exercise – there’s plenty in your fat stores.

    So, we need something that’s easily digested, and will support our blood sugar. That’s exactly the simple, refined carbs that we are avoiding in our normal diet. We don’t get an insulin response because we are burning enough carbs that we aren’t going to spike the blood sugar.

    And finally, when we’re done exercising, we haven’t quite refilled our carb stores, so we can take in some extra simple carbs and protein, and that will let us refill those carb stores.

    How does this work if we are trying to lose weight? We might burn 1500 calories on that 3 hour ride, but if we are taking in 250 cal/hour of carbs, we’ll only net a 750 calorie debt. So, if we don’t eat at all, we’ll lose more weight.

    But remember the blood sugar thing. Sure, we’ll have a 1500 calorie deficit at the end of the workout, but we’ll have to work hard to not to eat more than that when we’re done. Or, we can burn 750 calories of fat, replace the carbs, and – because we’ve kept the blood sugar constant – not replace the fat.


    The ultimate food for long rides…

    Phatty’s fictional post on how to be popular – fictional because of his delusion of popularity – reminded me of something that happened the last time that I did RSVP.

    I was riding with a group of guys that work at the same large software company that I do (yes, *that* large software company).

    The second day of RSVP starts in Bellingham, goes north and across the border into Canada, and wends its way north. After a while, it runs into the Fraser river in Fort Langley, where you will catch the Albion ferry to get to the other side. On the way to the ferry, there’s a small market, which Steve (not his real name) had been talking up for hours.

    I’m not typically one to eat a lot on long rides, but the Steve’s Rhapsodic descriptions of the effectiveness of the macaroni and cheese as a mid-ride meal swayed me, so I bought a small server and headed outside with the others to eat. Steve decided not only to have the mac & cheese, but also to have a piece of chicken.

    After a few minutes, he appeared outside with a large container of macaroni and cheese, a container of water, and a large roast chicken, which he bought “because it was cheaper that way”.

    Initially, he was exposed to a considerable amount of teasing, but by the time we got back on our bikes 15 minutes later, the bulk of the chicken had been consumed by the four of us.

    And, on that day at least, he was right about the mac and cheese.

     


    Nutrition Tips

    My triathlete friend Chris wrote a nice post a while back with some nutrition tips. It covers a lot of the same topics that I’ve been meaning to write about, so I’m going to use his post as a starting point.

    Carbohydrates and athletes

    Philosophically, my nutrition is very close to what Chris advocates – I eat one way for my normal diet, and eat differently around my workouts. As Chris notes, simple carbs are fine during exercise, but should be limited other times. The difference is because of the difference in the body’s needs during the two periods, and the explanation is going to be long and have a few sidetrips, but I’ll get there in the end.

    Basically, your body has mechanisms intended to regulate your blood sugar so that it stays in certain ranges. Your brain, muscles, and other systems are constantly pulling carbohydrate out of your blood, and your digestive system is providing carbs back into the blood. Since mammals don’t necessarily eat all the time, there are a couple of systems to smooth things out.

    First of all, your liver stores a fair amount of glycogen, and it will release it to the blood as needed. It will also make you hungry. If you are exercising hard, however, you will get appetite suppression, and eventually, you will run out of liver glycogen. At that point, your body goes into a survival mode – it can synthesize enough glycogen to keep your brain going, but not support exercise at the same time.

    This is the dreaded “bonk”, and the confusion that you get as part of a bonk is because you don’t have enough sugar in your brain. The amount of time it takes to bonk depends on how hard you’re exercising (higher intensity requires more carbs), your level of fitness (high trained individuals burn fewer carbs at a given intensity), and how full you muscle and liver glycogen tanks are. So, some people can ride 3 hours without bonking, and others might sometimes bonk after 75 minutes. Be especially observant with kids, as they don’t tend to eat as well or as often – my daughter bonked (or came close to it) on a bike ride last summer about 15 miles in because she hadn’t eaten much recently. I always carry a couple of gels in my seat pack for those situations, and that made her happier quickly (though not happy, as it takes days to recover from a bonk).

    So, anyway, that’s why having a supply of carbs during exercise is a good idea, but as Chris notes, you don’t need much – perhaps 150-250 cal per hour.

    If there is excess blood sugar, it will go to muscle and liver glycogen. If those are full, the liver will convert them to fat and save them for a rainy day. That mechanism has served mammals pretty well historically, but it evolved for the typical mammalian diet, and a situation where food is scarce. It has a few problems with refined carbs.

    Or, not really with the refined carbs, but with the stuff that has been refined out. You can eat foods that are high and sugar – such as fruit – but the absorption will be slowed down by the fiber in the food. Similarly, if your meal is a mixture of carbs, protein, and fat, the protein and fat will slow down the absorption of the carbs, and you will get a slow trickle of nutritents, which will keep you satisfied for a longer period of time.

    If you eat the refined stuff – sugar, white flour, white rice – you blood sugar goes up pretty fast, and your body will likely have to store some of it in fat, and your blood sugar will go back down.  So, that’s why the whole foods are better from a carb perspective – they keep you full longer. Not to mention their other health benefits.

    During exercise, things are different – your liver and muscle glycogen aren’t full, and the small amounts that you should eat during exercise will go to keep those sources full.

    Recovery

    It’s important to get protein and carbs very soon after exercise, to refill the liver and muscle glycogen stores and start any needed repair. If you don’t, your body will work to refill your glycogen stores by converting protein to glycogen. It gets this protein from your muscles, which would be bad. I have much less muscle soreness with carbs/protein drinks during and after exercise.

    I’ve had great results with Endurox, and there are other recovery drinks out there. Low-fat chocolate milk is pretty good if you tolerate the lactose well.

    The other huge advantage of a recovery drink is that it moderates your blood sugar, and you don’t get super-hungry after the workout, and then overeat.

    Sodium

    Finally, you need to think about maintaining your sodium stores. If you are eating fairly well, you probably aren’t taking in a lot of sodium, and you can easily burn through all of that sodium after a few hours of continuous exercise. Your sports drink may not provide enough sodium, so you may need to consider supplementation

     

     


    The importance of staying salty…

    Salt (or at least the sodium component of it) is perhaps the most underappreciated and under-discussed nutrient for endurance cyclists.

    Given my recent history, I’ve been doing a fair bit of research into the topic, and frankly I’ve been surprised how little information there is. That, coupled with a lot of bad press around sodium because of its well-established link to hypertension, means that most cyclists don’t think about salt. They do perhaps think a bit about hyponatremia.

    Which is really a bit strange, when you think about it, as many of us have white stains on our helmet straps and that sandy feeling on our faces after a hard ride.

    So, here’s what’s going on WRT salt, and a few things that you might want to think about.

    When you sweat, you lose salt, along with a number of other electolytes.

    Here’s a table I pulled from Burke’s Serious Cycling

      Sodium
    (mEq/L)
    Chloride
    (mEQ/L)
    Potassium
    (mEq/L)
    Magnesium
    (mEq/L)
    Blood Plasma 140 100 4 1.5
    Muscle Tissue 9 5 160 30
    Sweat 40-60 30-50 4-5 1.5-5

    This chart uses mEq/L, which is basically a measure of the concentration of the various elements. What we’d like instead is a chart that shows the actual amount of the substance (which we get by multiplying by the molecular weight). My wife tells me that medicine is the only place that uses mEq/L as a measure…

    Here’s the converted chart:

      Sodium
    (mg/L)
    Chloride
    (mg/L)
    Potassium
    (mg/L)
    Magnesium
    (mg/L)
    Blood Plasma 3220 3550 156 18
    Muscle Tissue 207 172 6240 365
    Sweat 920-1380 1065-1775 156-195 18-122

    This chart shows the difference between salt (sodium and chloride), and the other major constituents of sweat. For potassium and magnesium, the concentration in the blood is fairly low compared to the concentration in muscle tissue. This means that loses of those two elements through sweat are relatively unimportant to the body’s total supply.

    For sodium and chloride, however, the amount stored in muscle tissue is fairly minor. The majority of the storage is in the blood. And there’s really not that much there.

    So, say that you’re out riding and only taking in water. Your sodium level drops. Your body wants to get rid of the water, but it doesn’t want to lose more sodium, so it stashes the water between cells, and you’re on your way to hyponeatremia.

    This happens more quickly if you’re on a low-salt diet, which is what got me into this topic in the first place.

    What that means is that you need to replace the salt. Serious Cycling suggests that you need from 400-1100mg of sodium and 500-1500mg of chloride. ACSM recommends 500-700mg of salt/liter.

    Many hydration drinks have some salt in them – here’s a good comparison chart. Searching through that chart, I find that the accelerade that I drink only has about 500 mg of sodium per liter. That’s at most around 50% of the amount I need to replace the salt I sweat out (I’m a fairly salty sweater). Which explains a lot.

    Almost all of the the drinks have some electrolytes – as they’re needed to help you absorb the drink – but some of them are pretty low. So, take a look at what your drink has in it, and that will help you figure out if you need supplementation. If you are riding for long periods, my guess is probably *yes*.

    Symptoms:

    • Fatigue (yeah, I know, it’s a bit hard to judge after 60 miles)
    • Upset stomach
    • Headache
    • Aversion to sugary foods (I get this rather than a salt craving, though salt tastes good. This may also just be food fatigue)
    • Weight gain during the ride
    • Lack of urination, especially if you are drinking a lot.

    A note on hypertension…

    If you have hypertension (high blood pressure), this is an area that you will want to be careful with, and you may want to consult your physician before supplementation.

    What supplements to use

    A classic supplement is beef jerky, which tends to be around 1000mg per service. If you want a capsule you can swallow, both Lava Salts and Succeed E!Caps have a good reputation on the ultra (bike/run) sites.

    A lot of people talk about Hammer’s Endurolytes capsules. The hammer hydration products are quite low in electrolytes (see the chart I linked to earlier), and frankly, I’m mystified by what’s in the endurolytes – they only have 40mg sodium and 60mg chloride, which is a really small amount. They suggest that you can take up to 6 of them per hour, but even that may not be enough. They do have other electrolytes, but you are probably okay without supplementation of potassium and magnesium during exercise.

    One final note

    As with all things related to nutrition/hydration, people have different responses, so you’ll probably have to play around to find out what works for you. If you are used to sweating a lot, your body has likely adapted so that you don’t lose as much electrolyte when you exercise. Conversely, if you don’t work out in the heat and/or don’t sweat as much, you may be near the upper end of electrolyte loss.

    References

    Ultracycling has two great references on this:

    Low Blood Sodium

    Water and Salt Intake during exercise


    A miserable but learning experience…

    Yesterday I headed out with a few friends on a 120 mile 8000 ft “training ride”. The plan was to start in Enumclaw, ride up to the top of Chinook pass, descend and ride up to the top of Sunrise, eat lunch, and then return back to Enumclaw.

    I was a bit worried because I was riding with my friend Joe, who not only puts in at least twice as much mileage as I do but is also perhaps 30 pounds lighter than me. Luckily, Joe doesn’t mind riding slower so that others can keep up.

    My nutrition plan was to use the Perpetuem, to hopefully avoid the issues I’ve had with Accelerade in the past on long rides. I also brought a bunch of Endurolyte capsules to give me a little extra electrolyte, and some Newtons to chew on. I made up two “two hour” bottles – with enough perpetuem for two hours in each – and carried a camelback for the extra water. I usually don’t like to do that, but we were limited with water sources and it was hot hot.

    Joe had written up the ride as “16-18MPH on the flat”, which is what some of our other group rides. We tended towards the upper number (well, actually, above the upper number) for the first hour, which would have been very pleasant if not for the fact that we climbed around 1000 feet during that time. But, though my HR was a bit higher than I had planned (in the mid 140s rather than the 130s), that’s still right around my lactate threshold and I felt good and spent time talking with Greg as we rolled towards our first stop at Greenwater.

    The next 17 miles we picked up another 1200 feet of altitude, as we journeyed towards the entrance to Mount Rainier National Park. By that point, I was starting to feel a little out of sorts – I didn’t have the same sort of snap, but I knew that I wasn’t dehydrated nor was I down on sugar. I took a few more endurolytes. Then the fun began, as we climbed up Chinook pass (9 miles, 2400 feet)

    I did okay on the first part. I gapped off the back of the group – not a surprise – and just tried to ride my own pace, and finished the whole section in about 75 minutes. Not horrible, but not a lot of fun.

    A quick descent back down to the white river campground, $5 to enter, and it was time to work on the Sunrise climb. By this point, I was seriously down on both oomph and motivation, and the other riders just rode away from me (partly because I forgot one of my gloves at the water fountain, but mostly because I was so down on energy). I did okay on the first 5 miles – which aren’t very steep – but then the road kicked up and it was all I could do to ride on my smallest gear (a 30/27) at perhaps 80 RPM. I rode a mile or so, and stopped to take a quick break and stretch. After another 15 minutes, it was clear to me that I wasn’t going to finish the climb, and I stopped, sat for a while, phoned Joe and my wife to tell them what was up (interestingly, there was great cell coverage there. My guess is that we were using the towers at the summit of Crystal Mountain Ski area, which is just across the valley from sunrise (and sports the best view of Mt. Rainier around)). And then I descended back down, and started suffering…

    It was 26 miles from where I turned around back to Greenwater, which was the first place where I could get some real food. Suffice it to say that it wasn’t fun – I stopped a couple of times to rest, but it really didn’t help much. Eventually, I made it to Greenwater and stopped by the Naches tavern for some food.

    The chicken strips and fries did wonders for me, and I ate them with considerable amounts of salt. I tried a Coke but the fructose did not sit well on my stomach, so I only drank about a third of it. After about 30 minutes, I got on the bike and rode the remaining 18 miles back to Enumclaw. I got a little bit of snap back in my legs and started to feel better.

    The exact distance isn’t clear – because of me not remembering to start my new HRM – but it’s pretty close to 100 miles, with about 6500 feet of climbing.

    The whole experience is eerily reminiscent of my experience on STP last year. I felt good at the beginning, then after 3 or 4 hours started to really lose power. Both days were hot, and both days I sweated a lot.

    On the other hand, I did another hard climbing ride earlier this year (59 miles with 4K elevation) where I felt strong, but it was cool and overcast that day.

    Are you thinking what I’m thinking, that perhaps I was down on sodium?

    But that shouldn’t happen, should it? The perpetuem has electrolytes in it, and I was supplementing with Endurolytes. *But*, if you look at the labels, you find that Perpetuem only has 231mg in two scoops (a one-hour dose), and the Endurolytes only have 40m each. So, that puts me at about 350mg per hour of sodium. As a comparison, the Accelerade I use has 380mg in my hourly dose.

    Is that enough? I did a little research…

    While there are guidelines around how much sodium is necessary to help water absorption, there are differing opinions on amounts above that. In Serious Cycling, Burke reports a recommendation of 400mg to 1000mg per liter and ACSM recommends 500 to 700mg per liter.

    The amount you need depends on how acclimatized you are to the heat – more highly trained atheletes sweat more water and less salt. And it depends on your personal physiology.

    The anecdotal stuff I’ve read from the ultra groups (running, cycling, triathlons) says that at least for some people, salt supplementation is pretty important.

    During those long hours on the bike, I was seriously considering skipping RAMROD, but I’ve now decided I’m going to do it. But, I’m going to use a better salt supplement.

    A few pages I found useful:

    Ultrarunner

    Ultracycling

     

     

     


    What makes a good hydration drink?

    There are a lot of hydration (aka “sport”) drinks out there, ranging from the common Gatorade to esoteric ones like Gleukos. All make claims around why they are the best thing around and why all the other drinks suck.

    So, I thought I’d write a bit about my understanding of what makes a good drink and help you decode some of the labels out there.

    Calorie Density

    The first thing that you need from a hydration drink is a sufficient calorie density. Most experts suggest 250 calories perhaps up to 350 calories per hour. So, you need a drink that has that many calories when mixed with a sufficient amount of liquid to make a reasonable dent in your hydration needs (sometimes you may need more or less water). That puts carbs in the 6% to 8% range. Drinks with fewer carbs don’t provide enough energy, and those with more don’t provide enough water.

    Gastric Emptying & absorption

    Once you have the sugar solution in your stomach, you need to get it absorbed into the bloodstream. The absorption of the water in the hydration drink is increased both by the presence of the sugar (within reason) and by the presence of electrolytes. Fructose is a bit different than other sugars in this respect – see later in the post for more info.

    Sweetness

    Sweetness is a primary factor in whether you drink enough to meet your energy and hydration needs. There are two important points here:

    1. A sweetness that tastes good at rest is likely too sweet for a workout beverage, so you won’t drink enough of it…

    The second point is the most important one. Sucrose (table sugar) is arbitrarily given a value of 100 on the sweetness scale. The good hydration drink makers use different sugars to give you a product that isn’t too sweet but still packs enough carbs.

    Acclerade is primarly sweetened with sucrose but uses Trehalose (sweetness=45) to tone the sweetness down, and also a bit of citric acid to make it more sour.

    Perpetuem is at the other end of the spectrum, using Maltodextrin, which doesn’t have much sweetness at all, and to be frank, has a bit of a weird taste to it.

    Protein

    There is some good research around the benefits of adding protein to hydration drinks. Accelerade claims that their 4:1 ratio (using whey protein) is the best, Hammer claims that their 7:1 ratio (using soy protein) is the best.

    I like the protein, but it does make water bottles a bit messy. I soak mine full of water overnight to make them easier to clean, but you should still make sure never to put the lid on a dry bottle, lest it mold.

    Electrolytes

    Electrolytes are added to hydration drinks to speed their absorption. They also can replace the electrolytes lost to sweat but aren’t usually present in amounts that will replace all the lost electrolytes, so you may need to supplement.

    Simple or Complex carbs?

    There is a lot of marketing out there on the advantages of complex carbs or glucose polymers over simpler sugars. I’m somewhat skeptical of the claims of benefits (other than their lack of sweetness) – maltodextrin is (for example) rapidly broken down into dextrose.

    Food Fatigue

    If you ride for long periods – say, more than 3 hours – it’s not unlikely to find yourself unable to stomach another swig of your drink. This is known as “food fatigue”, and is a good argument for a variety of foods rather than a single one. 

    Bad Ideas:

    Plain Water

    Water by itself is bad for a few reasons.

    Most obviously, water doesn’t have any caloric value, so it doesn’t help towards your energy needs. But there is a more important reason…

    When you are sweating, your body is trying to maintain both your blood volume and the sodium concentration in your blood. If your blood volume goes down, you get thirsty, but if you drink plain water, that ends up diluting the sodium concentration in your blood, and your thirst is turned off.

    Not to mention the fact that water is absorbed less quickly by itself, which may lead to a waterlogged (ie “sloshy”) feeling.

    Now, if you’re using gels, solid food, or a concentrated drink, then when you add water, you get a good mixture, so that’s okay.

    Fructose in drinks

    Pre-mixed “original” Gatorade and powerade are both sweetened with high fructose corn syrup. Fructose is a bit of a weird sugar that has a couple of disadvantages:

    First, it has a different absorption mechanism that limits how much you can absorb over time. If you get more than the amount that can be absorbed, the rest will be unabsorbed in your digestive tract, which can lead to the dreaded “GI difficulties” (typically diarrhea). Some people have fructose malabsorption which may make this worse.

    Second, fructose gets processed through the liver, and is useful primarily in replacing liver glycogen rather than muscle glycogen.

    In hydration drinks, the sweetness of fructose is also a severe disadvantage, and premixed gatorade is quite sweet but low on calorie density.

    So, fructose is a bad choice as a primary sweetener, but not a problem as a secondary ingredient.

    Powdered Gatorade does not have fructose, and their “endurance” formula is a combination of sucrose, glucose, and fructose, so those are likely better choices.

    Fruit Juice

    Fruit juice has (no surprise) a lot of fructose in it, and tends to be very sweet.

     


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