How do I say this nicely?

OK… I read your blog post Dr. French, and you’re right. I am disappointed in your lack of belief in the basic science around endurance fueling. Also, while you’re not completely wrong, per se. You are, with the bits that matter.

Let’s take a step back and introduce Dr. French, who apparently is an “expert” at Hammer Nutrition. Dr. French is a doctor, actually has two doctor level credentials. He’s an MD, that practices family medicine, and a doctor of chiropractic. I don’t say that for any reason beside to highlight that Dr. French does not hold a PhD in sports science, sports nutrition, or any other field related to this topic. But, he’s happy to flippantly dismiss the actual science work of experts, who umm… actually work in this field. Like Dr. Tim Podlogar, Dr. Alex Harrison, Aitor Viribay Morales, or any of the other countless other experts who oddly enough do support high-carb fueling.

So it doesn’t get lost, I also do not hold a PhD in a related field (or any field for that matter). Which, depending on how you look at it, makes me just as qualified as Dr. French on this topic ;P. So let’s break down Dr. French’s opinion piece.

We have no nutritional requirement for carbohydrate.  I really don’t care if you believe me. Or if you think I’m “unscientific”, or are “disappointed” with my writing, as some have expressed (I am always trying to get better though).

This is not true of fat or protein. If we do not eat these we die. The healthiest and leanest patients I see do not consume carbohydrate as a staple. The healthiest athletes I see in my practice fuel with modest amounts of carb that is not sugar, and only with heavy, longer training sessions and competition. They are able to access fat for fuel and the generation of our coveted energy molecule ATP. More on this later.

This is weird one. Dr. French is probably technically correct here. Our bodies require fat and protein. They will convert fat and protein into usable energy. Protein is converted to glucose. Fat breaks down into different parts, some of which converts to glucose, some to acetyl CoA. Neither process is particularly efficient however. Which mean, you can do it, but it’s not the best way to do it. We run best on glucose. The body prefers it. In endurance sport, efficiency matters, why make it more complicated? Why not eat glucose and fructose (which is easily converted to glucose in the liver) when your energy demand is high? That just makes sense, and the body of science supports this. Even if you don’t believe in science you don’t need to look further than the performance gains directly correlated with high-carb fueling in World Tour Cycling.

Also, it’s worth pointing out that you don’t technically need fiber (or a host of other things) to stay alive. But, your quality of life is much better if you include it in your diet…

Intense and prolonged endurance pursuits on the regular are relatively new in our human experience. In a way, it could be considered unnatural. We are of course engineered for movement: lifting, traveling, and fighting, all the while procreating, but strenuous and repetitive activities (when conservation of energy was vital for survival) is new. Given that, nutritional requirements are different for those with a proclivity for endurance suffrage, as they would be for others.

I wish there was a nice way to say this, but there isn’t. Dr. French needs to read more. Humans have unique abilities when it comes to endurance activity compared to other mammals. We sweat everywhere. We don’t have fur. There is an ever expanding body of evidence within the scientific community that we are so good at endurance because we evolved to promote these traits. Dr. French, go look up “persistence hunting“. While you’re at it, might want to look up pre-human and early human diet. Then look at your teeth, because as well all know tooth structure tells an interesting story about evolution.

Most people and especially athletes are not fat adapted. They simply do not burn fat for fuel very well. This is probably you. Like a foreign language or pinochle, we can learn to become efficient burners of fat. Until this glorious day comes, the adage Carb is King rings true. I mean that most people will do better, most of the time, fueling with carbohydrate.

The difficulty arises when we ask how much carb and from what source?

Wait, what? I totally agree with Dr. French here. Most people aren’t fat adapted. Most people will do better with carbs. You can get better at burning fat. Where we divide is whether it’s worth it to bother. Where does fat adaptation get you? If your goal is long-slow-and-steady, and I don’t mean that in a pejorative way, and you don’t want to (or can’t) carry sufficient carbs; burning fat is your best option. But there are limits to how hard you can push. The body will eventually not be able to covert stored fat fast enough to cover your energy demand, and then you crash. In cycling, we call that “bonking”. So you do need to figure out your goals, and TBF Dr. French mentions the goals thing in the next paragraph.

Consider this. When human mammals, including well-conditioned athletes, consume large amounts of sugary crap, their blood sugar increases. The body knows this is a toxic situation and releases stress hormones like cortisol and epinephrine (adrenaline). Perhaps this “fight or flight” response is responsible in part for the modest increase in performance.

Respectfully, this is just wrong unless your endurance output is so low that the consumption of “sugary crap” puts you in surplus. So if you’re out hiking, or taking a walk around the neighborhood, you don’t need to fuel at a high level. You might be totally fine burning fat, even if you’re not “fat adapted”. It comes down to intensity.

Let’s do some quick math here to demonstrate this point. The basic formula to calculate energy consumption is Watts x Time in hours x 3.6. This does not include your BMR, or the calories you burn to keep you alive. It’s only the riding the bike part. So if you ride at 150W for 3 hours, it costs 1,620 calories. Or technically kJ, but that doesn’t really matter, and it doesn’t really matter if the body is 24% or 25% efficient. That is noise because the concept holds no matter what. It does not matter if we’re off by a couple hundred calories. There are 4 calories per gram of carbohydrate. Divide 1620 by 3, to get to hours. We get 540 calories per hour. Now divide that by 4 to get our carbs per hour target. That number is 135g/h. That is a big number. Average 200W over those 3 hours, and your new target is 180g/h. The longer the duration, the larger the deficit. Why not fuel in the most efficient way?

Your body is not going to freak out with a “fight of flight” response when you are burning energy faster than you can possibly replace it. This is why it’s totally fine to mainline “sugary crap” while you’re working hard, but it’s not OK to do it while you’re camped on the couch. Dr. French seems to deeply misunderstand metabolism.

A few companies and their vocal mouthpieces are currently making recommendations I consider harmful, on how much carbohydrate athletes should be consuming per hour. These guidelines are not based on powerful studies, meaning a large number of people were not followed over the course of many years. Nor are these recommendations based on any semblance of healthful action.

We do have a storage form of carbohydrate called glycogen. Intense exercise lasting about an hour or two is usually well fueled by this stored carbohydrate.

According to one high carb fueling author, “30-60 g of simple carbs per hour” is needed for intense exercise lasting 1-2 hours. I agree with this, and feel that this level of carbohydrate consumption is well substantiated by decades of research and experience, but regardless of the exercise duration!

This author goes on to recommend that for intense exercise over 2 hours, 60 to 90 g of carbohydrate per hour is needed. On What basis?

Sorry, Dr. French. It’s not just the “mouthpieces” who say that, there are myriad scientists who do not work for supplement companies that are saying exactly the same thing. And, as we just covered, it’s not harmful if you’re moving at sufficient pace. If you’re interested, you can see some of the science behind it here. If we look back at the math we just did, where does the energy come from if you’re not replacing it as you move past two hours? There’s really only one source, fat. Which, we’ve also already discussed the limitations around using it as the only energy source…

I have no respect for performing studies, funded by sources that sell products the studies are designed to support. To say nothing of the potential future liability issues associated with promoting the consumption of large volumes of a toxic substance (sugar) that drives the formation of cancer, cardiovascular disease, obesity, diabetes, and Alzheimer’s disease. That is not a legacy I would want.

What is that we say about people who live in glass houses? There is so much wrong with this statement. Sugar isn’t toxic, and I assume when Dr. French says sugar he means sucrose, or table sugar. It doesn’t cause these problems. Also, BTW, Dr. French anything that ends in “ose” is a sugar. Pretty much every plant based food contains sugars. Milk contains sugars.

Is Dr. French saying that Hammer Nutrition’s products cause cancer? Has he read the nutrition label on the products the company he works for sells? Some bold claims; where is the science to back it up? If you’re interested, below is a video by another MD who has some thoughts around it.

If the claim is that over-consumption is linked to disease. I agree that is valid. There is a significant body of evidence which supports that consuming more calories (the macro doesn’t really matter that much here, but there are different issues associated with difference macros) than you burn on a regular basis is detrimental to your long-term health. That’s not a sugar problem, for most people. Being overweight, however you got there, is the problem. A sedentary lifestyle is the problem. Sugar is not the problem.

Ultimately, Dr. French, makes a lot of unsubstantiated claims, and dismisses actual science work, but for the most part don’t show his homework. When he does, the one time, it’s a study that included 20 athletes. If we’re going to dismiss small sample carb studies it’s weird to turn around and base an argument on a single, small sample, fat-adapted study.

Let’s look at that study. The endurance activity was only three hours at 64% of VO2 Max. I wasn’t able to find a great way to convert that % number to a power zone (which I understand better), but given the duration and some quick back of the envelope stuff, that’s probably Zone-2 (someone correct me here if I’m way off base). In Zone-2 burning fat as an energy source is achievable. That elite fat-adapted athletes would burn more fat than elite not-fat-adapted athletes as the outcome, seems completely reasonable. If you read the conclusion, that is what the study demonstrates. I didn’t see claims beyond that.

Before we go, Dr. French included subject characteristics in his post, but omitted the whole table. I’ve included it below so you can understand the numbers a bit better. Having ten members per pool means that it is very important to look at all the numbers before drawing any conclusions from them.

Table 1. Subject characteristics.

The healthiest and leanest patients I see do not consume carbohydrate as a staple. The healthiest athletes I see in my practice fuel with modest amounts of carb that is not sugar, and only with heavy, longer training sessions and competition.

OK, since we’re doing anecdotes. I’m going to share too. As you might have guessed from the position I’ve taken here, I believe in science, and I like carbs. While I eat meat and fish, I am mostly plant based. Which means I eat a lot of carbs. I will be 49 in a couple months. Every indicator (BMI, body fat %, VO2 Max, blood pressure, fasted glucose response, etc.) I have available tells me that I am very healthy, even compared to someone 20 years younger than me. I eat (actually drink) sucrose (i.e. table sugar aka “Cancer Juice”) on every ride, no exceptions. I do vary the amount based on duration and intensity. While it would be fine for me to drink 100g+ on a 90 minute Zone-2 ride (based on my Zone-2); remember our math above. You don’t need to do that, and I prefer to replenish those carbs with whole food. On a longer ride, I will consume 100-125g/h. When a couple friends and I rode from Chicago to Milwaukee and back last summer, I consumed over 800g of table sugar and whatever carbs were in the apple pannenkoek I ate when we stopped for lunch.

I started down this path when I found that on long duration rides (races, centuries, etc.) I could not sustain intensity after a few hours. That’s what sent me down the high-carb path. Now the problem is fixed. I can do things I couldn’t do before. I do better on the rides. I feel better after. I recover faster after.

When you look at the science, all of that makes sense.