I don’t really consider myself an expert on anything, but I do know a thing or two about endurance nutrition and training. Nevertheless, I choose to coach on the training side only. If an athlete approaches me with a request for nutrition coaching, I refer them elsewhere. The reason is that I have found nutrition coaching to be frustrating and unrewarding. Whereas training right and eating right are both fairly simple in principle, in practice, eating right appears to be much harder for many athletes. All kinds of self-sabotage keep athletes from locking into a consistent set of healthy and effective eating habits. I’d like to briefly review the major forms of dietary self-sabotage in this post, with a special focus on a new study relating to one of them.
We all know the expression, “Don’t let perfect be the enemy of good.” Well, in the diet realm folks do this all the time. Who is more likely to eat an entire sleeve of Oreos in one sitting: a person who tries to never eat a single Oreo ever or a person who allows himself or herself to eat one Oreo every day? Science tells us it’s the latter. People who aim for dietary perfection (which is not even definable) tend to exhibit more erratic eating behavior and less -dietary self-control than people who merely aim for “good enough” in their eating habits.
We mustn’t overlook the fact that the single most common form of dietary self-sabotage, even among endurance athletes, is the virtual opposite of perfection targeting: giving up on trying to eat healthily. For most of us, eating healthily requires a concerted effort to break away from the Standard American Diet (SAD), which is the most convenient and comfortable way to eat in the U.S. and, increasingly, around the world. This effort proves to be too much for many athletes. It’s not a crime to eat too much fast food and sugar and not enough vegetables, but it does have consequences, and the one thing I really don’t like to see is athletes convincing themselves that they aren’t paying a cost for giving up and eating the SAD.
“Mirror enslavement” is my name for a form of dietary self-sabotage that entails focusing too much on outcomes and not enough on process. Scale enslavement is another version of the same phenomenon. Too many athletes decide that, either for performance reasons or aesthetic ones (or sometimes a muddle of both), they need to look a certain way or achieve a certain body weight by any means necessary, and the means they often choose is undereating. It’s much healthier to focus on building and sustaining eating habits that are proven to optimize health and fitness and trust that wherever these habits lead in terms of appearance and weight is where you need to be.
A lot of athletes are restless eaters—continuously bouncing from one fad diet to the next, one supplement or superfood or other nutritional magic bullet to the next. These athletes typically assume that the reason they’re always searching is that they haven’t yet gotten the results they want from anything they’ve tried, when in fact it’s the other way around: They haven’t gotten the results they want because they’re always searching. In other words, the true problem is not the diets themselves but the underlying restlessness.
This is not to say that specific fad diets are not also problematic sometimes. The fad diet that’s been causing the most problems lately for endurance athletes is the ketogenic diet, which systematically sabotages the fitness-building process by robbing the body of an essential energy source. Yes, I know that social media is teeming with testimonials from endurance athletes crediting keto for all kinds of miracles, but that ain’t science, and actual science tells us that adopting the keto way of eating as an endurance athlete is the dietary equivalent of riding a bike with square wheels or running with ski boots on your feet.
The latest scientific takedown of the keto diet is a study led by the legendary Louise Burke of the Australian Institute of Sport and published in PLoS One. Burke’s team actually repeated a previous experiment they’d done involving elite racewalkers, adding a twist that was intended to address criticisms of the original study lobbed by keto advocates who didn’t like the findings. Twenty-six elite race walkers were separated into two groups, one of which was placed on a high-carb diet (8.6 grams per kilogram of body weight daily) and the other on a ketogenic diet (<50 total grams of carbs daily) during a 25-day period of intensified training. Physiological and performance testing were done on both groups before and after the intervention.
What was different about this experiment was that, instead of doing the second performance test immediately after the “fat adaptation” process, the keto athletes were given 2.5 weeks to replenish their muscle glycogen stores by eating more carbs. In principle, this enabled them to have the best of both worlds, retaining the increased fat-burning capacity they’d earned through keto eating without being hamstrung by low carbohydrate availability.
The keto diet did achieve its objective of increasing fat-burning capacity in the athletes who followed it, their peak rate of fat oxidation during exercise jumping from 0.6 g/min to 1.3 g/min over the course of the 25-day intervention and remaining elevated through the replenishment period. However, as in the first experiment (and in other studies), this seemingly beneficial adaptation was not really beneficial at all, resulting in a sharp increase in the energy cost of walking at race speeds. On average, performance in a 10K racewalk event improved by 4.8 percent among athletes who followed a high-carb diet and decreased by 2.3 percent among those who were fat-adapted. Oops!
Long story short, be wary of fad diets. Elite endurance athletes eschew them, for the most part, and I encourage you to do the same. Indeed, emulating the core eating habits widely shared by elite endurance athletes (as described in The Endurance Diet) is a great way to avoid all forms of dietary self-sabotage.