Ask an elite athlete how nutrition factors into her performance, and she’ll likely tell you that it’s just as important as her training plan. In many cases, she may even call it the most important factor. But the increased effort levels during training can make sticking to your diet tough since even healthy regimens often include eliminating classic performance foods—like lean proteins if you’re vegetarian or carbs if you’re paleo. If you fall into one of these camps, rest easy. A few small tweaks will give your body what it needs to crank at its full potential. We spoke with two sports dietitians who work with high-performing endurance athletes—Heather Mangieri, spokesperson for the Academy of Nutrition and Dietetics, and Barbara Lewin, sports dietitian for the U.S. Olympic Registry—for the details.
If You’re Keto…
Keto dieters get about 75 to 85 percent of their calories from fat and eat very few carbohydrates (generally fewer than 50 grams a day). Although revered by many endurance athletes, the keto approach to healthful eating can backfire if you aren’t deliberate about finding your fuel elsewhere, getting adequately diverse nutrient intake, and tracking whether your body is adapting to fat burning.
Emphasize Diversity: You need a lot of vitamins, minerals, and natural antioxidants when you’re training. Without a careful approach to keto, you risk micronutrient deficiency, Mangieri says. Make sure you’re not eating the same rotation of foods. Instead, rely on easy swaps to ensure you’re putting a variety of vitamins and minerals into your body without having to take a supplement.
Monitor Your Performance: It’s been the silver bullet for many athletes, but the keto program doesn’t have the same impact on every individual, so it remains debated. Many people can run a marathon or do a tri while following the keto rules of thumb, but science shows that increasing intensity typically requires carbohydrates, Lewin says. She recommends keeping a journal to monitor what you’re eating and how you’re performing in your training. It’s key to see if you’re falling off pace or exerting more effort to clock in at slower times without necessarily noticing it.
If You’re Gluten-Free…
Gluten-free athletes avoid foods that most others consider essential to their training. Thankfully, “eating gluten-free is a breeze these days with so many healthy choices,” Lewin says. But there are still a few pitfalls to watch for.
Skip the Packaged Foods: A diet packed with gluten-free bread, crackers, and pastas isn’t inherently healthy or useful for fueling hard training, since those foods often have added sugar or fat to make them more palatable. Instead, “eat naturally gluten-free foods like quinoa and starchy vegetables like sweet potatoes or corn,” Mangieri says.
Go for Variety: Gluten-free dieters often eat a lot of rice products—rice bread, rice crackers, rice pasta—so they get a limited nutritional panel on repeat. Instead, switch up your alternative-carb products so you get a longer list of macros (and prevent stale taste buds). Try bean-based pastas, buckwheat pancake mixes, or corn tortillas instead of flour.
If You’re Vegetarian or Vegan…
Plant-based diets have become the darlings of the health world and the hallmark of many exemplary endurance athletes, but it’s surprisingly easy to eat a very unhealthy diet even when cutting out animal products. It’s less about what you aren’t eating and more about what you are eating, Mangieri says. “To really perform your best, you need to be a well-rounded vegan or vegetarian.” That means your pantry can’t be filled solely with energy bars and protein powder.
Pay Attention to Protein: Get your protein from real plants. There is a lot of amino-rich produce out there—you just have to be a little more conscious of making sure you’re getting enough. It may be worth using a food-tracking app at the start to guarantee that you’re getting the recommended 90 grams a day. Besides beans and legumes—lauded as plant-based protein sources—chia seeds, wild rice, oatmeal, and even potatoes contain significant amounts of plant protein that can be easily incorporated into your meals throughout the day
Be Mindful of B12: Strict vegans need to be sure they’re getting enough vitamin B12, which is naturally found only in meat and is essential for red blood cell production. Try incorporating fortified cereals or alternative milks a few times a day. If you’re really struggling to hit the mark, pop a B12 vitamin daily.
Time Your Fiber Wisely: “I recommend that triathletes and runners reduce their fiber for two days prior to their race, eating fewer big salads and the like. This may actually reduce their weight by a few pounds and will reduce GI issues and the chance they have to find a restroom along the way,” Lewin says. That’s tough for anyone who abstains from meat, but it’s important for being race-ready.
If You’re Paleo…
Athletes who fuel themselves on this ancestral diet eschew agricultural-era foods such as grains, legumes, dairy, and refined foods while focusing on meat, fish, fruits, and veggies. It’s pretty easy to be a paleo athlete as long as you time the carbs you do eat for adequate fueling and recovery.
Enjoy Those Well-Timed Potatoes: The Paleo Diet for Athletes allows high-glycemic carbs like potatoes around your training and racing times to ensure you have adequate glycogen stores for high-intensity efforts and recovery.
Make Your Own Sports Drinks: Commercial sports drinks will be off-limits, but you can make your own from raw honey, sea salt, lemon juice, and water.
If You’re Practicing Intermittent Fasting…
Some athletes believe this approach helps them stay lean and fast. “There is good research that this pattern of eating can be beneficial. You just need to practice it wisely,” Lewin says.
Eat Enough: For athletes, the goal of intermittent fasting isn’t to go into starvation mode or to shed pounds quickly. Instead, it’s meant to increase your strength-to-weight ratio by triggering your body to burn fat stores. When you do eat, you want to make sure you consume enough to maintain muscle mass, restock your glycogen store, and stay fueled.
Time It Right: Schedule your high-intensity sessions close to your last meal so you have fuel on board. Avoid prolonged fasts of more than two to three days just before races so you don’t go in with depleted glycogen stores.
If You’re Eating Only Raw Foods…
Raw-food practitioners, notably professional triathlete Brendan Brazier, fill themselves with foods that haven’t been cooked, believing that modern cooking deleteriously alters food’s nutritional content. The foods you choose and how you prepare them can have a major impact on how well (or not) you do as you train.
Prioritize Protein: It’s easy to feel satisfied on uncooked foods yet miss out on getting the protein you need. Raw, less-processed food fills your stomach faster even if it doesn’t give you lasting energy. To combat this effect, eat a large variety of nuts, seeds, legumes, and vegetables, rather than just munching on raw crudités and trail mix, to get all your essential amino acids without filling up first.
Think About Fiber: Fiber hits harder with a raw-food diet because your body has to do all the work of digesting it without the help of cooking, which might ordinarily kick-start the breakdown process. “A high fiber pre-workout or pre-race meal doesn’t sit very well and usually doesn’t provide adequate calories,” Lewin says. “The same is true for recovery. Eating a high-fiber recovery meal means that you miss the window of 20 to 30 minutes after your workout where the body is able to most efficiently restore muscle glycogen levels and rebuild muscle.” Juicing some of your foods will help eliminate some of the fiber while still providing nutrition.