Food, Weight & Performance: Changing the Sports Nutrition Conversation
Written by: Nancy Clark, MS RD CSSD
Most of us who work with athletes have heard comments such as these:
“I want to lose weight so other cyclists don’t drop me on the hills.”
“I plan to shed a few pounds before the marathon to be able to run faster.”
“Losing weight would really improve my Power to Weight ratio…”
While lugging around excess body fat can certainly hinder athletic performance, will weight loss help an already-lean athlete perform better? Or does the cost of losing weight (poorly fueled muscles, higher risk for injuries) limit the benefits of being lighter and supposedly faster, swifter? Here’s some food for thought:
- When pondering the Power to Weight Ratio, most athletes focus on fat loss instead of power gain. Losing fat is hard. (How many athletes do you know who have been trying to lose the same 5 pounds for the past 10 years…?) Losing fat is even harder if you are already leaner than others in your family. Gaining power is easier!
- Being lighter and leaner works to a certain extent. The trouble starts when weight-reduced athletes enforce a restrictive diet for months, if not years, to maintain a leaner physique. Injuries start to happen—repeatedly!
- Among 126 recreational male marathon runners, race times correlated best with training (number and length of workouts, miles per week), not percent body fat—unless body fat was more than ~17%. Runners with 8.5% to 14% body fat had similar marathon run times (1).
- Wrestlers who repeatedly lost the most weight over seven seasons sustained more injuries than those who lost less weight. Cutting weight increased risk for getting injured (2).
- Restricting food means restricting fuel. Among top female soccer players, the average daily carbohydrate intake was only about 200 grams a day—half of the recommended 350 to 500 grams (6 to 8 g carb/kg body weight) needed to properly support hard exercise (3).
- While most elite soccer players report knowing “carbohydrates are important for athletes,” they still restrict their carb intake, perceiving carbs as “fattening” (4). A high-protein, high-fat chicken Caesar salad doesn’t do the refueling job. More sandwiches please!
- Athletes who “carb load” pre-event should know they will likely gain a few pounds. Immediate weight gain linked to carb intake is water-weight and means the athlete is better fueled. Each 1-gram of carb stored as muscle glycogen holds about 3-grams of water.
- Both males and female athletes who have low energy availability (LEA) can experience low sex hormones, low thyroid hormones, low bone mineral density, and a higher risk for bone injuries. One study reported athletes with LEA lost ten-times more training days due to injuries compared to those who consumed adequate fuel (5).
- Among young girls, body fat gain associated with puberty is often seen as a threat to performance. Some girls go to great extremes to cut back on food and curb the developmental changes that are supposed to happen. Athletes younger than 18 years should not manipulate their body weight (6)! Parents, coaches, and teammates alike need to learn how to talk comfortably about puberty and the body changes that are supposed to happen throughout middle and high school.
- Super-runner Mary Cain’s story sums it up: “I was the fastest girl in America until I joined Nike” (7) Mary had been shamed about her weight and pressured to get smaller because her breasts and bottom had become too big. She lost her period for three years and broke 5 bones.
- Mary Cain’s terrible experience opened the door for other athletes to become more vocal and demand a culture change that is now happening. Body fat measurements are no longer taken at many colleges (8).
- Even the US military has changed their focus from percent body fat to performance (9). Soldiers need to be strong and powerful. The military now uses Fat-free Mass Index* as a way to track musculature. (*FFMI = fat-free weight/height)
The bottom line
As PINES sports dietitians, we need to educate athletes around the globe—
- To train to improve performance, not to burn calories and lose weight.
- To consume adequate calories so they are not living in energy deficit.
- To remember that restricting food means restricting important nutrients (protein, iron, zinc, calcium, etc.) and increases risk for injuries.
- To enjoy the success that comes with being well fed, healthy, strong, and powerful.
Author
Nancy Clark MS RD CSSD counsels both fitness exercisers and competitive athletes in the Boston-area (Newton; 617-795-1875). Her best-selling Sports Nutrition Guidebook is a popular resource, as is her online workshop. Visit NancyClarkRD.com for info.
References
- Tanda, G & B Knechtle. Marathon performance in relation to body fat percentage and training indices in recreational male runners. J Sports Med, 4:141-9, 2013
- Hammer E. et al, Association of in-competition injury risk and the degree of rapid weight cutting prior to competition in Division I collegiate wrestlers. Br J Sports Med 57(3):160-165, 2023
- Morehen et al. Energy expenditure of female international standard soccer players: A doubly labeled water investigation Med Sci Sports Exer 54(5):769-779, 2022
- McHaffie et al. Carbohydrate fear, skinfold targets and body image issues: a qualitative analysis of player and stakeholder perceptions of the nutrition culture within elite female soccer. Sci & Med in Football, 2022
- Heikura et al. Low energy availability is difficult to assess but outcomes have large impact on bone injury rates in elite distance athletes. Int J Sport Nutr Exerc Metab 28(4):403-411, 2018
- Ackerman, K et al. REDS: time for a revolution in sports culture and systems to improve athlete health and performance. Br J Sports Med 54(7):369-370, 2020
- https://www.nytimes.com/2019/11/07/opinion/nike-running-mary-cain.html
- https://www.nytimes.com/2022/11/10/sports/college-athletes-body-fat-women.html
- Harty et al. Military body composition standards and physical performance: Historical perspectives and future directions. J Strength Cond Res 36(12): 3551-61, 2022
