The endurance athlete’s guide to fueling and weight loss part 6: Recommendations

This post will make considerably more sense if you have read the previous posts

After five long and sometimes tedious posts, I’m finally going to tell you exactly what your base diet should be and and how to fuel during exercise to achieve your goals.

Ha.

I sincerely wish I could do that, but the reality is that everybody is different (genetics, age, sex, metabolic condition) and we all have different goals (win that race/lose weight/have fun), so I’m not able to do that.

What I do think I can do is talk to you a bit about my philosophy of endurance eating and fueling and how you might apply it to your situation. And then I’m going to turn you loose to experiment/adapt/modify the recommendations to adapt them to your specific situation.

Philosophy

Based on the way our biochemistry works, here’s are the principles I advocate:

  • Train in ways to improve fat burning, and therefore improve the ability to use fat as a fuel so that more fat is burned and less glycogen is used, so there is less hunger.

  • Fuel in ways to support glycogen stores and therefore support endurance and performance without getting in the way of fat burning.

  • Eat in ways to support the first two goals and to leave us generally healthy.

The application of these principles is going to depend on your current weight, fitness state, goals, number of cats you own, etc. In the following sections I’m going to talk about some broad guidelines, but you will need to do experimentation and tuning yourself.

Train in ways to improve our fat burning

Doing training to specifically increase fat burning has been a thing for a long time; there was, for example, a big push towards LSD (either Long Steady Distance or Long Slow Distance) training in cycling in the early 2000s. And it worked okay, at least for some people.

But what it was missing was the dietary and fueling aspect; if you have a lot of glucose in your system during the training, you get improved endurance but you get little improved fat metabolism.

While thinking about this section, I remembered a mountain training ride I did with a couple of friends back in 2006 or so; it was scheduled for about 115 miles and around 8K of up. I was getting ready, stuffing my jersey pockets with little ziplocs of drink mix and other foods – probably 1500 calories worth – and I noticed one of my friends just standing there. I asked him what he was taking for food, and he pulled out a little bag of trail mix. He said, “I usually don’t eat much on rides, but I’ll have some of this if I get hungry”. Another paradox that the “you have to eat lots of carbs” model doesn’t explain.

The way that we improve our fat burning is exercise in situations where glucose is scarce. What does “scarce” mean in practice?

I don’t know.

Perhaps “scarcer” would be a better word to use, and in fact fits in better as I advocate an incremental approach. Take the amount of carbs that you eat before/during/after, and reduce it by some amount.

If you generally don’t eat on your workouts, pick one of your workouts – perhaps a longer weekend one – and do it fasted.

If you are a carbs before/during/after kind of athlete, look at the amount you are eating and cut them down. From a biochemical perspective, targeting the pre-workout carbs – so that you start with lower glycogen stores and steady blood glucose – is probably going to be more impactful, so maybe you cut down or eliminate that snack first. Or maybe you cut down all your carbs by 30%. And then go out and do your workout.

Generally speaking, longer steady workouts are much better for this than fast short ones. Use whatever definition of “long” that works for you.

Do that for a few weeks or even a month or two, evaluate how it’s working compared to your goals, and see if you want to make further changes.

Fuel in ways to support our glycogen stores

Didn’t I just tell you to reduce your carbs during training, and now I’m telling you to increase them?

Not quite.

While there are some athletes who eat full keto (very low carb) diets and use either no or very few carbs during workouts and races, there’s no prize for doing that nor is it a morally superior approach.

What we are trying to achieve biochemically is to have enough available glucose for our muscles to support us for the exercise so that we can achieve our goals, both from a weight perspective and from a performance perspective.

If we are doing the “better fat burning” training described in the last section, then the best approach can be described as “the minimal amount of carbs required to keep you from bonking”, as that will give you the most improvement in fat burning. We will deliberately eat in ways that put us close to running out of glycogen. Which is why it is absolutely essential during this training to carry carbs with you, especially if you are starting from a high-carb fueling strategy, because it is very hard to know exactly how close you are to bonking. If you start to get hungry and/or feel your energy dropping quickly, eat some carbs.

If you are in this purely for the fat burning side, then stick with this strategy. You will increase your fat burn during the ride and reduce the amount you eat during the ride. Both are good.

If your session is more performance/endurance sensitive – perhaps a goal event or a intense training session – then look at how long/hard it is going to be, make a guess at how many carbs you will burn, and plan a replacement strategy so that you have comfortable reserves at the end. If you are a better fat burner than before you won’t need as much as you did before, but you will likely need some. The pro cyclists who work to be very good fat burners still eat a *lot* of carbs during a hard day of racing.

Small amounts of carbs on an ongoing basis can be a pain to implement. If you want a simpler approach, consider UCAN’S SuperStarch, which acts like a time-release glucose. and is therefore quite convenient to use. Pricey, however. (note 1) I use it on my longer & harder events – say 4+ hours – but generally don’t on shorter events, where I just have water, even if fasted.

Recovery nutrition

Conventional wisdom says that you need to refill your glycogen stores as quickly as possible to take advantage of the brief window where glycogen replacement is increased when exercise is finished. The window does exist, but in most cases, we don’t really need our glycogen stores to be refilled especially soon, and those are extra calories that aren’t required. There’s an interesting study that shows that having the post exercise carbs reduces insulin sensitivity and glucose tolerance the next morning.

On the other hand, if you want to have something sweet, right after exercise that has depleted your glycogen stores is biochemically the best time to do so, and in particular, it’s a time when fructose likely doesn’t have the same downsides (note 2), so some fruit can be nice. I like peaches.

My general advice is to tend to not eat targeted recovery food, but if you find that you are ravenously hungry after long workouts, a bit of carbs after exercise can blunt that reaction.

Eat in ways to support the first two goals and to leave us generally healthy

Diet is a huge topic that I could write endless posts on. I will try to keep it simple and at least mostly related to the goals that we have been talking about.

Limit refined carbs and processed food

Refined sugar (sucrose) is an obvious target, and it’s bad for a lot of reasons – there is lots of glucose that you have to deal with, and lots of fructose that can lead to insulin resistance. Note that sucrose is added to a significant number of processed foods; this is a byproduct of the 1980/1990ss fat phobia, when manufacturers found that reducing fat made food taste awful but you can make it taste less awful if you add a lot of sugar. So, you’ll need to read labels.

And now for a bit of heresy… I think you should be careful with the amount of fruit you eat. There are many fruit advocates that assert that the sugars in fruit behave differently than refined sugars and therefore fruit is not an issue. It *is* true that:

  1. The sugar is bound up in the flesh of the fruit so that it takes longer to be absorbed than sugar outside of the flesh.
  2. A piece of fruit is much more filling than the equivalent amount of refined sugar.

But that just means that fruit is a gentler source of sugar, not that you can eat as much as you want. The impact of fruit hasn’t been well-studied in clinical trials, but I did find a study that looked at the relationship of fruit consumption to gestational diabetes, and the effect was significant (note 3).

If you have a lot of extra weight and/or type II diabetes, I would try to get rid of as much fructose as possible, from all sources.

And some more heresy… I think that other refined carbs are also important, though not as important as sugars. They lack fructose, but they still have a big load of glucose in them. This is mostly anything made with wheat flour (even whole wheat flour), so bread, pizza, pasta.

Yeah, I know, I like them all as well. I used to eat a lot of them when I was younger but they don’t agree with me now that I’m on the far side of 50. YMMV.

Alcohol is also something to limit, for the same reason as fructose.

And yes, I’ve totally killed the “ride and then celebrate” scene. Sorry to be such a buzzkill.

Choose an appropriate fat/carb ratio for your situation

From a general health perspective, the data I’ve seen suggests that if you are healthy in general and insulin sensitive, you will probably do fine on a moderate carb/low fat diet or a low carb/ moderate fat diet, as long as its a whole food diet (note 4). So just choose one that works for you.

If you are insulin resistant and/or have not being able to reduce your weight easily in the past, I’d recommend trying one of the low-carb approaches as they make more sense for that metabolic state. I usually recommend either Mark Sisson’s Primal, or the Duke University “No sugar No starch” diet.

Like the changes in fueling, I recommend that you make any dietary changes on an incremental basis.  If you end up going low carb, there is quite a bit of anecdotal data that suggests that endurance athletes are generally happier with diets that have a few more carbs in them (ie not keto), and an interesting study here where none of the participants stuck at a very-low-carb/keto diet but they all did eat a significantly lower-carb diet than they had in the past.

Case studies

Because my advice is non-specific, I thought I’d include a few case studies that have specific examples of what people have done.

One of the posts that started me on this journey was noted cycling coach Joe Friel’s blog post entitled “Aging: My Race Weight”.

My case study is in my blog post Down 20?

Chris Froome and other Team Sky cyclists use a low carb diet a their base diet – Froome famously tweeted this picture of a rest day breakfast that was very low carb. They do supplement with carbs based on the event. There’s a bit of insight into their approach here.

In Closing

I hope this has been helpful. If you have questions, please send me a comment; I’m planning on a follow-up post to clear up things that weren’t clear.

Notes

  1. SuperStarch is an interesting story. There is a disease called glycogen storage disease where a person is unable to store glucose as glycogen, and therefore is unable to regulate their blood glucose. The traditional treatment was corn starch every 2 hours, which was hugely impactful. SuperStarch is corn starch that has been modified so that the starch molecules become very long, which means that is slowly digested and therefore results in a slow release of glucose – exactly what is needed for people with this disorder. It also turns out to be quite useful as a carb replacement fuel for athletes. Here’s a paper with links to the clinical studies does with SuperStarch.
  2. Fructose in combination with high blood glucose preferentially metabolizes to fatty acids, which can accumulate in the liver. But if you have depleted glycogen stores, the glucose in the fruit goes straight into those stores and the fructose gets metabolized to more glucose.
  3. The odds ratio between the group that ate the most fruit and the group that ate the least was 4 – those who ate the most fruit were 4 times as likely to get gestational diabetes than those who ate the least. That is really a ridiculously high ratio for a nutritional study; it is uncommon to see anything above 1.5. It was still an observational study, however.
  4. Gardner’s DIETFITS study is a pretty good one. I recommend watching his video here.

So, what do you think ?