Changing up your nutrition can make a huge difference in your performance, but if you decide to try out a new kind of approach, there are some things to consider first. Most specialized diets weren’t designed for the athlete, so they’ll likely need to be tweaked to fit your individual needs. “When starting any diet, always ask yourself: Is this sustainable? Do I have the finances to do this repeatedly? And is this the right diet for my performance goals?” says nutritionist Marisa Faibish, director of performance nutrition at Appalachian State University. As an athlete, here’s what you need to know about some of the most popular plans out there.
In theory, the paleo diet encourages you to eat only things that could have been hunted or gathered by our caveman ancestors. That means lots of meats, fish, greens, local veggies, nuts, and seeds. Packaged foods and refined sugar are totally out, and starchy vegetables, grains, fruit, dairy, beans, and legumes are eaten sparingly or not at all, depending on who you talk to. The paleo diet also eliminates alcohol and salty foods. (You can see exactly what a day of eating in the paleo diet might look like with our paleo pyramid.)
You’ll eat more whole foods and fewer processed goods, as well as develop a sense of how certain ingredients make you feel, Faibish says. “The diet also deters you from drinking alcohol, which can sometimes have a negative impact on performance,” she says.
Dairy, grains, and legumes—all eliminated with this diet—are great sources of protein, vitamins, and minerals that your body can use for overall performance and recovery, Faibish says. Plus, without grains, it can be nearly impossible to get enough carbs to power tough training blocks or high-mileage weeks. Faibish adds that another missing ingredient—salty foods—could actually benefit you by replacing the electrolytes you lose in sweat from exercise.
Whole30 markets itself as a short-term, 30-day method to reset your diet. You cut out items that are known to upset some digestive systems—all processed or packaged food, natural and artificial sugars, alcohol, grains, beans, legumes, soy, and dairy. You’re also told to avoid meals that, while they might be made entirely from approved ingredients, are supposedly not good for you. (Something like a pancake made with just egg whites and banana is still a no-go.) Confusing and excessive? We agree. But in addition to giving your digestive system a break, Whole30 also works to help rewire your brain to crave whole foods.
If you’re looking for a fairly drastic kick-start, this could be for you. Keep in mind that it was designed for only 30 days, so if you last that long, you can ease your restrictions and modify the diet to be sustainable for your long-term needs.
You need to have margins for error as an athlete, and this diet doesn’t give you any, says Leslie Bonci, nutritionist and owner of Active Eating Advice. It’s also labor intensive and difficult for people who travel or eat out often, because you can’t guarantee you’ll have access to the allowed foods. “Not only is it unrealistic, but it’s also very low-calorie,” Bonci says. It’s a diet built for weight loss, not a plan built to support performance. (Also, just a warning: no peanut butter.)
The high-fat ketogenic diet is, at its most basic level, a diet of 75 percent fat, 20 percent protein, and 5 percent carbohydrates. Our keto pyramid gives you an idea of what a day in the life of the keto diet really looks like. It’s extremely restrictive, nixing all fruit, grains, starches, legumes, sugar, alcohol, and processed foods. The carbohydrate reduction should eventually move your body into ketosis, prompting the body to access fat stores as its primary source of fuel, rather than carbohydrates, which are typically the primary source.
A study in Metabolism: Clinical and Experimental found that when elite endurance athletes slightly tweaked that ratio and consumed a diet of 70 percent fat, 19 percent protein, and 10 percent carbs for between six and 20 months, they had a peak fat-burning rate more than two times higher than the rate of their peers who were consuming a more carbohydrate-heavy diet. The increased ability to burn fat for fuel during exercise spares muscle carbohydrate stores, which can improve or prolong exercise performance, explains study co-author Daniel Freidenreich. That’s because an athlete can bonk once muscle glycogen (carb stores) reaches a certain low level or becomes depleted. There’s also research showing that ketones produced in athletes on a low-carb ketogenic diet can help fuel the brain, which might further prevent zeroing out during endurance activities, Freidenreich says.
Studies haven’t definitively proven that an increase in fat-burning translates to optimized performance, Bonci says. She also notes that the heavy load of fat may not be easy on everyone’s GI tract, especially at the start. “And logistically, you’re not necessarily going to pack your avocado and coconut oil for a long trek,” she says. Another drawback is the so-called keto flu, which happens to many people during the first four to six weeks on the diet, when your body is adapting to the new normal. Side effects include fatigue, nausea, dizziness, and brain fog as a result of your body switching from burning carbs to burning fat. “Exercise performance will likely suffer during the first few weeks of adapting to a low-carb diet, so athletes should plan to transition to the diet before their competitive season,” Freidenreich says.
There are several different patterns of intermittent fasting, but all variations require restricting your food intake to a specific time period. A few include the 16/8 method, where you fast for 16 hours and eat two to three regular healthy meals during the eight-hour period; the 5:2 diet, where you have no more than 500 to 600 calories for two days out of the week; and the eat-stop-eat method, which involves a 24-hour fast once or twice per week. The theory is that when your body is in a fasted state, it’s more likely to pull energy from your fat sources since there won’t be readily available glucose.
Some athletes claim fasting makes them faster, but the science is thin. There is research, however, to support intermittent fasting as a method for weight loss. If that’s your goal, this diet could be a possibility for you. Athletes will need to consider which timing interval makes sense for them with regard to their training schedule, so they aren’t training on empty. “Try to train or exercise during your eating window or days,” Faibish says. “For example, with the 5:2 diet, schedule your harder, longer, and more strenuous workouts on days that you are allowed to eat, and have your lower, shorter workouts on your fasting days.”
“We all know that when we exercise, we use energy, and in order to get energy, we must eat,” Faibish says. “So if we are restricting ourselves from eating and have a hard HIIT training session, do you think you are able to perform at your best?” More than likely, you will be drained. “If you are a morning gym goer, having to fast till noon may be extremely difficult for you as well,” Faibish points out.
You may have seen the #IIFYM hashtag on Instagram, which stands for “If It Fits Your Macros.” The diet is pretty simple: It doesn’t involve cutting out entire food groups, restricting your eating times, or even ditching processed foods. Instead, you calculate how many grams of carbs, protein, and fat you should be getting each day to reach or maintain a specific weight, given your gender, age, height, and current weight.
This plan is also known as flexible dieting—you can eat virtually anything you want on it. (Think of it sort of like the old-school Weight Watchers points system.) For many people, that’s far more attractive than having to cut out entire food groups or give up every indulgence. Rather than target your health from the inside, this plan tends to create the biggest changes in how people look on the outside. Those who are either looking to bulk up quickly or lose a few pounds in a shortish period often give this a shot.
Because there isn’t a focus on food groups, you could easily do this diet by eating junk food. (Maybe that’s a pro for some.) Similar to the myth that all calories are created equal, all macros aren’t created equal either. “This diet neglects micronutrients and phytochemicals that are important,” Bonci says. “Athletes are not one size fits all, and they need to be able to customize nutrition to their goals.” Plus, there are certain vitamins and minerals every athlete needs that this diet might lack.