Ideal Body Weight and Athletic Performance

By Terry Zeigler, EdD, ATC 

Does losing body weight enhance performance? This is a difficult question to answer and one that may be more complicated than initially thought. Female athletes tend to want to lose weight to be leaner and to improve performance. But, is there a direct correlation between weight and performance? The problem for many athletes is that regardless of whether there is a correlation or not, many coaches and athletes believe that weight loss is directly correlated to improved performance.

Scale Weight versus Body Fat Composition

Looking to standardized weight charts is not helpful when dealing with the health and proper weight of an athlete. Because muscle mass weighs more than fat mass, female athletes tend to weigh in at the top ranges for their height when being weighed on a scale. Athletes may mistake their weight as too high based on standardized weight charts.

Because weight charts are not a reliable and/or accurate source for determining an athlete’s healthy weight, sports medicine professionals may opt for measuring the athlete’s body fat percentage. Body fat is a component of overall body composition. The body’s composition can be divided between lean tissue (muscle, water, bone) and fat tissue.

The percentage of body fat of an athlete can be calculated based on skinfold measurements of subcutaneous fat (fat stored just beneath the skin). Although this method is good if used by an expert, it can be unreliable in the hands of an amateur. Even with a professional performing the skinfold measurement, there is still a margin of error (plus or minus 3%).

Determining the amount of body fat through underwater weighing is more accurate but it takes expensive equipment to be able to perform. Although there are other methods of measuring body fat (i.e., electrical impedence), underwater weighing is still the gold standard when it comes to measuring body fat.

While there are ranges of body fat that are listed for females (20% – 25%) and female athletes (16% – 22%), an important question to ask is who decided these ranges and what criteria did they use to determine the ranges of body fat? Second, might there be different ranges depending on the sport that the athlete competes in?

For example, it would be understandable that a cross country runner would be on the lean range (14%-16% body fat). Would the same be true of a swimmer or a basketball player? How about a catcher competing in fast pitch softball? Could healthy percent body fat ranges even be correlated to positions within a sport?

Does Lowering Body Fat Percentage Improve Performance?

So the question that needs to be answered is this – does lower percent body fat improve performance? It really depends on what the athlete’s body fat percentage is to begin with. If an athlete is already at 15% body fat, reducing more body fat will most likely not result in an improvement of performance especially if her skill level is already high.

However, if a female athlete has a body fat percentage of 30, losing body fat may improve performance in a number of ways. Reducing overall body fat can improve the body’s ability to perform because a reduction of fat reduces the strain on the cardiovascular system. Less body fat also means less weight for the muscles to have to carry and move during activities.

Last, a percentage of body fat that is too high (greater than 30%) increases the loads on the weight-bearing bones which may make the athlete at risk for bone, joint, and tendon injuries (i.e., stress fractures in tibia, patellar pain).

Another consideration is that reducing weight in unhealthy ways (i.e., starvation, excessive exercise, purging) does not only reduce body fat, but muscle mass also. So athletes may actually be decreasing their performance level by using these weight loss methods.

This is why it is critical that coaches and athletes understand the difference between scale weight and body fat percentage. If an athlete is concerned about her scale weight, she needs to get her body fat percentage measured by a sports medicine professional. If it is in a healthy range, she needs to be counseled to not pursue dropping any weight.

If the athlete is insistent that she still needs to drop weight, she needs to be counseled as to the physiological risks of dropping more weight, and to determine what the driving force is behind her desire to lose weight (i.e., coach’s comment, poor self-image, peer pressure).

Female athletes who drop below 14% body fat can be at risk for a number of physiological side effects including loss of menstruation, hormonal disorders, loss of muscle mass (when the body is starving, it will use existing muscle as an energy source), increased injuries, and bone loss.

What is driving athletes to believe that they need to lose weight?

The answer to this question is multi-faceted and may include pressure from coaches, pressure from the athletes themselves, peer pressure, or types of uniforms worn.

Unfortunately in the world of sports, many people who coach sports hold degrees in other academic fields besides kinesiology or a related field. While the coach may have a degree of knowledge regarding a specific sport, the coach may not have a good enough understanding of basic physiology to understand body composition, weight, and their effects on performance. This problem may be compounded if the coach also has a lack of knowledge about designing and implementing conditioning and weight loss programs for their athletes.

Ignorance from coaches can cause an athlete who may be predisposed to eating disorders to start on the path of disordered eating. Although sports do not directly cause eating disorders, a coach who sets weight limits on his/her athletes may unintentionally be the trigger that can lead to dieting, restricting calories, and then ultimately disordered eating.

Coaches may also not understand the significance of either an off-handed or intentional comment to a female athlete about her weight. Before comments are made to an athlete, significant thought needs to go into the purpose of the comment and the effect it may have on an athlete.

If a coach does not have the needed expertise in understanding the link between female athletes and disordered eating, he/she should seek out advice from a professional. Understanding the complexities of disordered eating and female athletes should be a requirement for all coaches who choose to work with female athletes.

For example, because of the negative psychological and physiological effects of mandatory weigh-ins or body fat measurements on female athletes in sports teams, the Canadian Academy of Sports Medicine issued a position statement calling for the abandonment of routine body composition assessment in female athletes. Following suit, several other national sports and medical organizations “have suggested that both weigh-ins and body composition assessments be eliminated or at the very least be used with extreme caution (Beals, K., 2004).

In other words, group weigh-ins where the coach measures the weight of his/her athletes should be discontinued in sports. Mandatory weight limits should also be discontinued. Both of these protocols may lead to extreme dieting in athletes.

Even without the assistance of a coach, athletes may apply their own pressure to lose weight because they believe that it may improve performance. If the athlete has a higher than normal body fat percentage, this may be true. However, for athletes in normal weight ranges, this rationale is not supported by research.

Coaches need to pay attention to athletes who appear to be in a normal weight range but who continue to insist that they need to lose weight. These athletes need to be identified and referred to a professional who can educate them as to what a healthy body weight is and refer them for psychological counseling if warranted.

While sports offer many positive psychological and physiological benefits for athletes, one possible down-side is learned pathological disordered eating behaviors. Although most athletes are willing to get help for their peers with eating disorders or disordered eating, some may actually assist in teaching the behaviors.

Uniforms and Athletes with Eating Disorders

Adding extra pressure for female athletes to diet and restrict caloric intake is the focus on the outside appearance of athletes by the uniforms that are worn in some sports. When athletes are required to wear uniforms that are body tight and expose a lot of skin, athletes may be self-conscious about how they look.

For example, female athletes in the sport of basketball and soccer wear uniforms that are loose and baggy. These athletes would not be the ones feeling the pressure of their outward appearance. However, athletes competing on a girls or women’s volleyball team may.

Volleyball uniforms have decreased in length over the years and now consist of tight form-fitting “bun-huggers” and form fitting shirts. Is it possible that the volleyball uniform may place an athlete at risk for disordered eating? This is a question that needs to be asked of the volleyball industry.

Does the current uniform enhance performance? Biomechanically speaking, tight uniforms are worn in other sports (i.e., track and field, swimming) to decrease the amount of drag on the athlete’s body for the purpose of improving performance. Reducing drag does not appear to be a factor in a gym setting. So what purpose does it serve to place these athletes in these uniforms?

Other sports require tight fitting uniforms (i.e., leotard in gymnastics) because judging the lines of the body is part of the sport. This same thing could be said for dance, competitive cheerleading, and figure skating. It is also these sports that have a higher incidence of eating disorders in their athletes. It is understandable that these athletes are concerned about their body image when they are on display in front of their peers.

However, what needs to be taught to athletes is that athletes come in all shapes and sizes. Some female athletes will have larger and more developed muscles than others. Some athletes may be taller or have broad shoulders. All of these are genetically determined and cannot be changed by the individual. Athletes who have a healthy body composition need to be taught to embrace themselves and their bodies and become comfortable with the skin they are in.

Educating Coaches and Athletes about a Healthy Body Composition

Educating coaches and athletes about how to achieve a healthy balance between muscle development and body fat composition is a good place to start a discussion. Talking about the importance of developing muscle mass is as important as talking about the necessity and benefit of a healthy body fat percentage.

Athletes need to develop their muscles because stronger muscles tend to correlate with improved performance as long as the motor skill development is there. Developing muscle mass may increase an athlete’s scale weight. This is a good thing and one that needs to be understood by both coaches and athletes.

A healthy body fat percentage is also important for the health of a female athlete. Athletes should know the ranges of body fat that are healthy as well as those ranges that are unhealthy. If an athlete has an unhealthy percentage of body fat, she needs to be counseled by a sports medicine professional as to how to make healthy changes in behavior to modify the percentages.

Some athletes will have larger bone structure than others. An athlete with larger bone structure and greater height will not be able to achieve weight restrictions without compromising her health. Coaches need to understand this factor and not place weight restrictions on their athletes.

Open discussions need to occur within female sports teams about body image and healthy weight management. Talking openly about body image is one way to bring the discussion about the dangers of eating disorders out in the open. These kinds of discussions may also provide an athlete with an eating disorder the courage to ask for help.

Coaches, athletic administrators, and all those who work with female athletes need to understand the link between disordered eating and female athletes and eliminate procedures or protocols that may place an athlete at risk for an eating disorder. Teaching girls to be comfortable in their own bodies is an important aspect of working with girls and women’s sports.

References

Beals, K.A. (2004). Disordered Eating Among Athletes: A Comprehensive Guide for Health Professionals. Human Kinetics: Champaign, IL.

Ray, R. & Wiese-Bjornstal, D.M. (1999). Counseling in Sports Medicine. Human Kinetics: Champaign, IL.

Thompson, R.A. & Trattner Sherman, R. (1993). Helping Athletes with Eating Disorders. Human Kinetics: Champaign, IL.