Changing Your Shape

Athletes, like most people, come in all shapes and sizes. In some sports, a low body fat level is important, for example, a marathon runner who must carry their own body weight over long distances. In other sports, success is partly based on the athlete’s appearance, like bodybuilders, gymnasts and divers, who strive for a trim and taut look to impress the judges.

Many factors contribute to achieving the optimal body shape for performance. When making any dietary changes, your priority should always be to stay fit and healthy.

Losing body fat

In sports, a low body fat level may be desirable for several reasons:

  • To decrease the amount of weight to be carried, especially over long distances (e.g. a marathon runner)
  • For appearance reasons (e.g. a gymnast)
  • To improve the power-to-weight ratio (e.g. a sprinter)
  • To make the weigh-in requirements in sports with weight divisions (e.g. a lightweight rower, a boxer or a judo player)
  • Getting the lean advantage

Body weight is a poor indicator of fatness in active people. The more you train, the more muscle mass you will have. Since muscle mass is much greater than fat mass, your body weight can actually increase through increased exercise. Changes in weight can be due to fluid losses like sweat, food still being digested from the last meal and changes in the level of muscle glycogen (every gram of glycogen is stored with approximately three grams of water). A better way to assess your body fat level is to see an exercise physiologist or sports dietitian, who can take your body fat measurements with skinfold callipers.

Here are a few guidelines for a safe and healthy way to lose body fat:

  • With the help of a sports dietitian, set realistic and healthy body weight and body fat goals
  • Plan to lose between half to one kilogram per week. One kilogram of fat equals about a 10mm decrease in your total skinfold measurement for 9 sites
  • Eat slightly fewer kilojoules than you currently eat rather than crash diet
  • Eat enough carbohydrate to provide energy for your muscles during training. If you eat too little carbohydrate, you can get tired very quickly and this can affect your performance
  • Your fat-loss program should still include foods you enjoy and some of your favourite foods for special occasions
  • Avoid cutting out whole food groups such as meat or dairy simply to lose weight, as you may miss out on vital nutrients like protein, calcium and iron

Making weight

If you compete in weight-matched sports (e.g. boxing, wrestling, judo, horse racing and rowing), it is often necessary to weigh in before and sometimes after the event. Unfortunately, some athletes compete in a lower weight division than their training weight, and often they try to do this by losing three to six kilos in a few days before competition. This has prompted the use of drastic techniques such as dehydrating in saunas, diuretics, laxatives and spitting. These methods may effectively cause a loss of body weight, but body water, muscle mass and glycogen stores will be lost as well, which means poorer performance and potential health risks.

To perform at your peak, it’s best to start the competitive season at your best weight for your sport. Unless you train and compete year-round, competition time is not the time to “make weight”. Instead, being close to your best weight should be an all-year goal.

Consult a sports dietitian to determine your ideal competition weight. They can also help you with strategies to reach this weight.

Bulking up

Some athletes dream of looking like Arnold Schwarzenegger. They may try to buy this dream with pills, potions, powders and six to eight meals a day. Athletes in strength-based sports such as throwing events and weightlifting are interested in increasing their muscle mass to enhance their strength and power. If you’re one of these athletes, you need to push yourself with a challenging strength training program and "top off" your daily food intake with extra kilojoules. Despite all the claims, there are only a few real requirements for muscle gain, and these, in order of importance are:

  • Your genetic make up – your ability to build muscle is partly determined by your genes and this cannot be changed!
  • Weight training – muscles need the right stimulation to grow
  • A higher energy diet – a “bulking” diet needs more of everything, including carbohydrate as well as protein