If anyone's prone to the commission bias—the tendency to do something versus doing nothing—it's endurance athletes. In search of a performance edge, we try it all, from donning vascular pump boots, to chugging beet juice, to shaving our forearms.

But perhaps the most common act of commission is nutritional. Endurance athletes are all too happy to seek an advantage in the dietary abyss: paleo, vegan, gluten free, low-carb, low-fat, Zone...the list goes on and on.

It has to stop.

According to Matt Fitzgerald, a top sports nutritionist, this boundless dietary experimentation is unnecessary at best and detrimental to health and performance at worst. “I’ve kind of developed a cottage industry of saving athletes that go on some sort of extreme diet and see their results and health suffer,” says Fitzgerald.

However, the allure of extreme diets is easier to understand when the alternative, the standard American diet, has made the majority of our population overweight or obese. (The outlook isn’t much better in other developed countries, either.) So what is an athlete who wants to maximize health and performance to do?

“Eat like the elites,” says Fitzgerald. For his upcoming book, The Endurance Diet, Fitzgerald traveled the world to investigate nutrition practices shared by elite athletes across disciplines. He uncovered these five common principles that anyone can follow:

#1: Eat Everything

“Avoidance of entire food groups is very common at the recreational level, but absent at the elite level,” explains Fitzgerald. Aside from allergies or actual intolerances, the pros eat vegetables, fruits, nuts and seeds, healthy oils, meats and fish, whole grains, and dairy. “Amateur athletes often cut something out in an attempt to lose weight, or because they’ve been told to by marketers, but this almost always backfires,” says Fitzgerald. The two most common pitfalls to avoid: eliminating grains, which increases risk for illness and injury, and eliminating meat, which increases risk for anemia.

#2: Eat Quality

Just because the pros eat everything does not mean they eat the same quantities of everything. According to Fitzgerald, “The best athletes load up on high-quality foods, really focusing on fruits, vegetables, lean meats, and whole grains.” While everyone breaks down and indulges once in a while, for serious athletes, “in moderation," especially when it comes to highly processed junk food, actually means rarely.

#3: Eat Carbs

Fitzgerald is adamant that one of the worst mistakes a performance-minded athlete can make is to go low carb. “The best case scenario [for an athlete that eliminates carbs] is that you end up right where you were before, when you were eating carbs. But only after subjecting yourself to a period where you feel and perform worse. And that is the best outcome,” he says.

“The risk of eating too much is a few extra pounds, whereas not eating enough can sabotage your training and performance.”

More commonly, “athletes that cut carbs end up on the sidelines with injuries,” warns Fitzgerald, because the glycogen depletion can negatively affect hormones involved in recovery, like testosterone. “Outside of some nonsense anti-carb ideology, there is hardly any reason to do it,” he says. Perhaps the only reason to go low-carb is targeted weight loss, which cutting carbs can help with, so even Fitzgerald recommends doing so occasionally. But when he does, Fitzgerald limits low-carb diets to “the end of the off-season, well before an athlete is ramping up with harder training.”

#4: Eat a Lot

The top athletes are always more worried about not eating enough than eating too much. “The risk of eating too much is a few extra pounds,” says Fitzgerald, “whereas not eating enough can sabotage your training and performance.” While some athletes may see short-term gains from limiting calories and rapid weight loss, no one achieves long-term success while under eating. “This is why eating disorders are common at the collegiate level and nearly non-existent at the elite level,” explains Fitzgerald. “You simply cannot stay on top if you are not healthy.”

#5: Eat for Your Lifestyle

Rather than follow a dogmatic diet, elites allow for individuality, syncing their nutrition program with lifestyle constraints and cultural context. “They [elites] don’t minimize the importance of nutrition, but they don’t make it harder than it has to be either,” says Fitzgerald. And whenever elites do tweak their diets, they pay close attention to cause-and-effect, “applying the same kind of mindfulness to nutrition as they do to their training,” says Fitzgerald.

In the end, you are what (and you perform how) you eat. While nutrition should be an important priority for athletes, it should not become a cause of anxiety or stress. According to Fitzgerald, being concerned about what you put into your body is okay: that’s often part of being a serious athlete, or a foodie. But when feelings of worry or guilt associated with food become common, a problem could be on the horizon. If that occurs, it is prudent to consult a nutritionist or psychologist.

Still, the most widespread problem with sports nutrition is a lack of clarity, says Fitzgerald. “It’s crazy to me that every athlete at the elite level eats based on the same principles and it works, yet at the amateur level, people are eating so differently, following radical diets founded in reductionist science instead of real world proof.” The most common thing Fitzgerald hears from athletes that consult him? “I am confused.”

Hopefully this article helps clear things up.