5 Nutrition Rules for Performance Training

Social media platforms like TikTok and Instagram provide a glimpse into the lives of athletes, including their dietary habits.

Although athletes' meals may appear similar to the average person's, their eating patterns are significantly different, and for good reason.

Athletes push their bodies to extreme limits, and food plays a crucial role in supporting their performance. However, conventional “healthy eating” guidelines, emphasizing fiber, protein, and vegetables while limiting added sugars and salt, may not be sufficient to achieve their athletic goals.

To highlight the distinctions between “healthy eating” and fueling for sports, we consulted top registered dietitians to gather the advice they frequently provide to their female athletes (across all age groups) that contradicts common practices.

This does not necessarily imply that you should follow this advice. Instead, we hope these insights emphasize that the definition of eating well varies depending on the context. We encourage an inquisitive and non-judgmental approach to differences in food choices and recommendations.

Stevie Smith, MS, RDN, CSSD, CDN, a board certified sports dietitian based in Buffalo, New York, specializes in helping active women enhance their performance without compromising their health and well-being.

Christina Anderson, M.S., RDN, CSSD, CSP, known as The Gymnast Nutritionist®, assists gymnasts (along with their parents and coaches) in learning how to fuel their bodies for optimal performance and longevity in the sport.

At mindbodygreen, protein has been a focus for several years, particularly ensuring women get enough. However, for athletes, carbohydrates are the most important macronutrient.

“Athletes need significantly more carbohydrates than the average semi-active individual,” says Stevie Smith, M.S., RDN, CSSD, CDN, board-certified sports dietitian. Carbs are broken down into glucose, the body’s primary energy source for endurance sports, such as running, biking, triathlons, swimming, and rowing.

When you consume carbs, some glucose is used immediately by cells, while some is stored as glycogen in muscles and the liver, providing energy reserves.

Endurance sports require a high level of energy expenditure over an extended period, making a large glucose supply essential.

Carb-rich foods have often been viewed negatively in the wellness community, with many people, including athletes, considering foods like bread, pasta, and rice unhealthy.

“There is still a lot of fear surrounding carbohydrates in athletes,” notes Smith. “But as training intensity increases, carb intake must also increase.”

Smith emphasizes that proper carb intake before, during, and after workouts is crucial for athletes to replenish muscle glycogen and improve post-workout recovery.

The best way to fuel before and during a workout is with quick-digesting carbs, which are foods that mainly provide sugar.

“One of the most contentious topics of nutrition in a sport like gymnastics is the use of quick digesting carbohydrates intra-workout,” says Christina Anderson, M.S., RDN, CSSD, CSP, The Gymnast Nutritionist. “The lay public doesn't understand the differences between ‘fueling vs. snacking’, and so you'll see a lot of things—especially on social media—saying that sports drinks are toxic, full of sugar, etc.”

But this is actually the exact fuel that athletes need.

Anderson emphasizes that high-intensity sports (like gymnastics) can have grueling four to six-hour practices, and quick-digesting carbs are needed every hour and a half to two hours. Sports drinks, or snacks like dried fruit, gummy candies (yes, fruit snacks!), gels, and crackers—all foods that many people try to avoid to eat healthy—are crucial for performance nutrition and keeping the muscles and brain fueled. 

“The stomach gets limited blood flow during exercise which can compromise digestion, so we have to use a fuel source that can digest easily like fruit snacks, processed carbs (grains), etc.,” emphasizes Anderson. 

This not only applies to gymnastics, but also sports like tennis, soccer, running, football, and so on that span hours. 

“It doesn't matter whether you think these foods are healthy or not. It's about using the right fuel source at the right time if you want to maximize performance,” asserts Anderson. 

Anderson clarifies that the idea of allowing gymnasts to have their favorite candy is not about encouraging them to eat candy all the time, but about finding a balance.

There's a challenge with the prevalent messaging about healthy eating, which often focuses on limiting sugary foods and categorizing foods as good or bad.

Anderson, who works with young athletes, their parents, and coaches, emphasizes that the emphasis on healthy eating can lead to over-restriction of "fun foods," including quick-digesting carbohydrates, resulting in unintentional underfueling. Both of these can negatively impact physical and mental well-being at any age.

Anderson highlights that many high-level gymnasts struggle with regulating their intake of sweets, often leading to overeating, sneaking, or binging. This behavior doesn't improve even after they stop competing. Anderson suggests making these foods "emotionally neutral" by providing them frequently and with permission.

Smith typically advises her clients to avoid filling up on vegetables, a recommendation that may seem unusual coming from a dietitian.

Smith explains that consuming large amounts of vegetables at meals and snacks can leave the stomach feeling too full, limiting the intake of essential carbohydrates from grains or starches and sufficient protein. While some people intentionally use this strategy for weight management or fat loss, it can hinder an athlete's performance.

Smith recommends including vegetables at each meal but keeping the serving size to 1/3-1/4 of the plate, depending on the athlete's training schedule.

Many health enthusiasts track their macros and sometimes calories to monitor their health. But Smith believes this approach is too restrictive and does not account for the ebbs and flows in training throughout the week, and the unique needs of athletes.

She says that, “Many of my clients come to me after working with macro coaches. They are under-fueled and experiencing negative health and performance outcomes. It also very often creates or perpetuates a negative relationship with food and exercise in most endurance athletes.”

To address this with clients, Smith starts by seeing where the biggest gaps are and what small, daily changes will have the most impact. “This might be starting with a small carb-rich snack before a morning workout instead of fasting, or bumping up sources of protein for athletes for those who are underfueling,” she says.  

Did you notice that all the advice on this list is about ensuring athletes have enough energy availability? Both Smith and Anderson brought up the dangers of underfueling (not eating enough to support daily energy needs, workouts, and recovery) that can lead to relative energy deficiency in sport (REDs)