Research Review: Nutritional Needs of Female Athletes

Don’t Put Yourself At Risk From Low Energy Intake

In a world where obesity is becoming the norm, undereating gets less attention. A new review shows this is putting female athletes at risk. Low Energy Availability, defined as eating fewer than 30 calories per kg of fat free mass a day, is a widespread problem among athletic women and girls that puts them at risk of health problems and poor performance.

Low Energy Availability (LEA) alters the balance of hormones, causing disruption of menses, or amenorrhea. It has long-term consequences, including low bone density, poor immunity, and fertility problems. Athletic performance may drop by anywhere from 1 to 10 percent. Cardiovascular, gastrointestinal, and psychological issues may also result.

Athletes in aesthetic sports are at greatest risk of undereating, but there is evidence that this phenomenon is prevalent across the board for female athletes:

• In a study of Division 1 female runners, 52 percent reported LEA.
• Among Division 1 female soccer players, 33 percent reported LEA, which was associated with greater body dissatisfaction.
• LEA in American high school athletes was reported at 36 percent, whereas in professional ballet dancers it was 77 percent.

Despite the prevalence of LEA in athletic women, awareness and effective treatment are low. Sport coaches often put pressure on female athletes to lose weight or restrict calories, exacerbating the problem. There also may be a culture of food restriction or eating disorders that encourages dietary behaviors that effectively lead to self-sabotage.

What Happens When You Undereat?
Energy availability is an important concept in sports. It is the amount of energy per kg of fat free mass that is remaining following the energy expended during exercise. Low Energy Availability is a calorie intake that is too low to allow for optimal physiological functioning. It leads to alterations in hormones that cause a reduction in resting metabolic rate (RMR) as the body tries to conserve energy by shutting down nonessential physiological functions.

Although many athletes purposefully restrict calories in an effort to lose weight, others may have LEA due to increased training loads or lack of awareness around energy requirements. For example, high training volumes can lead to appetite suppression or athletes may limit food in the effort to minimize GI symptoms in the face of multiday training sessions. Another contribution to LEA is when athletes switch to a popular new diet such as a vegetarian, plant-based, or keto diet.

How Does Regular Dieting Impact Performance?
Surveys suggest physical performance declines by as much as 10 percent in response to chronic dieting. One study found that in elite adolescent swimmers, those with LEA had a 9.8 percent decline in swim speed over 12-weeks compared to a group that had adequate calories and had an 8.2 percent improvement in performance.

Solutions To Low Energy Availability
Experts call for female athletes to work with experienced sports nutritionists to devise an eating plan that optimizes performance and body composition. Targeted workout nutrition is essential to prevent the loss of lean mass, support exercise performance, and avoid hormonal changes that lead to menstrual dysfunction and related health problems. In some cases, counseling can be helpful to aid female athletes in navigating the social messages and norms that get in the way of optimal nutrition.

What follows are general nutrition recommendations that athletes and coaches can use when designing nutrition programs:

Estimate calorie needs and hit energy intake goals daily.
Nutrition protocols should be day specific to meet training and recovery needs. For example, a training day that includes 3 to 4 hours of training may require a calorie increase of 30 to 50 percent compared with a recovery day. Scientists recommend the ideal calorie intake is between 39 and 45 cal/kg fat free mass/day.

Incorporate workout nutrition.
Workout nutrition is extremely important to offset catabolism of lean mass. Studies suggest that athletes with menstrual dysfunction and hormonal changes spend a greater period throughout the day in a state of catabolism making pre- and post-workout nutrition in the form of protein and liquid carbs key for promoting recovery.

Optimize essential nutrients.
Athletes have higher requirements for essential nutrients involved in energy metabolism. LEA puts athletes at risk of nutrient deficiencies, making supplementation worthwhile. Iron, vitamin D, calcium, and magnesium are all key nutrients for athletic performance and recovery.

Carefully plan weight loss interventions for the off season.
If weight loss is the goal, significant care is required to design a well-constructed weight loss program. Calories should not go below 30 calories per kg of fat free mass a day with the ideal range being between 30 and 45 calories/kg of fat free mass. Ideally, nutrition interventions should be achieved in the off season to avoid performance decrements or jeopardize health.

Troubleshoot obstacles to optimizing energy intake.
Consider appetite and psychological factors that may impact an athlete’s adherence to a nutrition protocol. Appetite doesn’t automatically increase with higher training volumes and athletes are often reticent to increase calories if they are concerned with body composition.

Be especially cognizant of the risk of LEA in female athletes competing in weight class sports or those where leanness is valued. Be aware that sport coaches, teammates, or parents may pressure athletes to lose weight or limit energy intake.