• Fitness & Health
• Sport & Exercise Science
• Physical Education
• Strength & Conditioning
• Sports Medicine
• Sport Management
• Dance

Weight, body composition, and performance in athletes

This is an excerpt from Dietary Supplements in Sport Performance by Kimberly Mueller,Lonnie Lowery.

If a group of athletes were asked what they would most like to change about themselves to improve performance, chances are one of the most popular answers would involve losing body fat or improving body composition. However, a common misperception among certain athletes is that leanest is always best. Of course, fat loss or maintenance and gain of lean mass doesn’t always equate to improved performance—with the possible exception of bodybuilders. All athletes are genetically different in terms of body types and body composition. There is no single equation for altering or determining body composition. Altering body composition is dependent on energy and nutrient intake, with consideration to partitioning—that is, which body compartment receives them. For some athletes, severe calorie restriction is required to reach and maintain a lean body composition, but this type of restriction will negatively affect performance. Athletes must be wise about making attempts to lose body fat. Body composition, whether it be fat loss or muscle gain, should be a focus during off-season training when peak performance is not required.

Fat Loss

A decrease in body fat essentially means that an athlete will be running, jumping, swimming, and changing direction with less mass or weight to move. For example, a male athlete who weighs 165 lb (74.8 kg) and has 10% body fat carries 16.5 lb (7.5 kg) of adipose tissue, or body fat. If the athlete reduces his body fat to 7%, he has lowered his fat mass to approximately 11.5 lb (5.2 kg); his body is more efficient with 5 lb less body fat to move. A leaner, lighter athlete moving with less body fat will be more efficient and expend less energy doing the same task as someone who is carrying more body fat (or even excess muscle mass). In addition, athletes such as high jumpers or sprinters want to maximize their strength-to-mass ratio in order to optimize their performance. However, maintenance of strength and power is key while minimizing body weight or mass. If strength is lost along with mass, improvements in performance will not be realized.

The desire for athletes to be leaner, along with a need for many nonathletes to lose weight, has created an explosion of fat-burning and weight-loss supplements. These supplements are one of the most popular types of products on the market, with nearly 200 names and brands of so-called fat burners currently available for purchase online. Unfortunately, fat burners and weight-loss supplements are also some of the most dangerous: They can contain potent stimulants that can affect cardiovascular function and even result in death, and they are often adulterated with ingredients or pharmaceuticals not listed on labels that may have powerful, often harmful effects on the body. Extreme caution should be used when choosing these products.

Most fat burners and weight-loss supplements can be assigned to one of three categories:

1. Stimulants. These contain stimulants such as caffeine, synephrine, guarana (containing caffeine plus other compounds), and many others. Some ingredients, such as ephedra and 1,3-dimethylamylamine, are now banned by the FDA. Product claims include the ability to speed up resting metabolic rate and burn fat.
2. Appetite suppressants. These include Hoodia gordonii and others that assist in controlling appetite and limiting calorie intake.
3. Fat malabsorptives. These ingredients limit the amount of fat absorbed during digestion, resulting in lowered calorie intake. Chitosan, which is a structural element found in the shell of crabs, shrimp, and lobster, is a popular ingredient found in weight-loss supplements due to its purported ability to bind fat and prevent its absorption. These types of products can have some undesirable side effects such as loose stools and diarrhea. In addition, their use will also limit the absorption of fat-soluble vitamins, healthy fats, and essential fatty acids need for optimal function.

Muscle Preservation and Hypertrophy

Muscle mass and hypertrophy are part of the broader category of body composition change. The typical textbook estimation that it takes approximately 2,700 kcal of surplus energy intake, along with additional protein, suggests that gains take weeks to months to be noticeable, even in an exercise physiology laboratory. Muscle mass and quality are important considerations for athletes and for general health. Curtis and colleagues (2015) point out that as one ages, “factors underpinning muscle quality come into play, including muscle composition, aerobic capacity and metabolism, fatty infiltration, insulin resistance, fibrosis and neural activation.” A number of these characteristics, although typically considered in the context of avoiding sarcopenia (muscle loss with aging), help underscore the fact that building quality muscle mass with a combination of resistance exercise and surplus nutrient intake is of critical importance. Of course, some sports such as bodybuilding focus almost entirely on muscle aesthetics as opposed to function—indeed, the development of sports supplements has been strongly influenced by bodybuilding. Although many sports supplements are targeted toward bodybuilders, they are also used by other athletes hoping to build lean body mass. Conversely, athletes of some endurance events seek to optimize—rather than maximize—muscle mass, because extra weight could decrease their performance.

More Excerpts From Dietary Supplements in Sport Performance

---