Nutrition and Diet » Weight Management in Athletes

THE MECHANICS OF WEIGHT LOSS

The primary goal of sports nutrition will be to provide adequate energy to the athlete. Energy balance is achieved when the athlete consumes the same amount of energy as they are metabolising. Energy balance is essential for maintenance of lean muscle tissue mass, immune and reproductive functioning, and optimal athletic performance. When athletes reduce their energy intake to less than their energy output, then fat and lean tissue mass become the body’s fuel sources. This can result not only in weight loss, but also reduced strength and endurance. Chronically low energy intake can also result in nutrient deficiencies. Weight loss should be carefully monitored and in certain cases, supervised by a medical professional. A weight control program will usually aim to reduce the number of calories consumed, and increase the amount of aerobic and resistance exercise performed. Certain behavioural modification may also be necessary, as people may eat when bored, depressed, or in other behavioural situations.

WHY DO ATHLETES WANT TO LOSE WEIGHT?

In skill based sports such as archery, an athlete’s performance will be largely independent of how much fat the athlete is carrying. In other sports, such as sumo wrestling, it may actually be advantageous for an athlete to carry more body fat than the general population. However, in many sports – and in particular, endurance events, the athlete with a lower body weight will actually have an advantage over larger athletes. There is less dead weight for the athlete to move around. Indeed, studies have identified a positive statistical link between performance and body fatness – athletes with lower levels of body fat do better in certain sports. This has fuelled much interest, and in some cases obsession with achieving lower body fat levels. There are big limitations to such studies, because body fat levels vary so much with the individual. There are no good studies in which the performance of individual athletes has been monitored across a range of body fat levels

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“Making Weight” and “Cutting Up”

In certain sports such as boxing, athletes will fit into weight categories – and in these cases, athletes may wish to manipulate their weight to fit into a certain category, rather than for a health goal. Generally athletes will want to fit themselves into the lowest weight class possible, to give them the maximum strength advantage over their opponents. This is known as making weight. In most cases, athletes will “make weight” just prior to competition by food restriction, extra training, and dehydration.

Body builders will also use similar techniques to “cut up”, so that muscles and veins are sharply defined against low body fat levels and dehydrated skin tissue. For making weight, athletes reduce their body mass by reducing the body fluids, the amount of food in the gut, muscle fuel stores, and occasionally loss of muscle protein. Methods used to achieve this include:

• Dehydration by exercising in the heat

• Sweating in a sauna

• Taking laxatives and diuretics

• Eating less

• Taking in less fluid

• Induced vomiting.

In these kinds of sports, athletes will have a “weigh in”, where they are put into a weight category. There is usually a small period prior to competition where the athlete can attempt to recover from the deprivation. It is usually too short a time to allow full recovery. This is not possible for athletes like jockeys who will have to certify their weight again after competition.

There are lots of problems associated with rapid loss, and they are examined elsewhere in this lesson. Specific problems include:

• Severe dehydration – in some instances, this is as high as 5-10% of body mass.

• Low glycogen stores in the muscle and liver – this has an adverse affect on exercise performance.

• Poor nutrient supply

• Changes to hormonal and metabolic function

• Increased fatigue, anger, anxiety, depression, and food stress due to having to make weight.

Athletes in sports where they have to make weight should get expert advice to determine their appropriate competition weight division that will not compromise their physical health and performance.

WEIGHT LOSS AND PHYSICAL PERFORMANCE

A significant weight loss after intense exercise is usually due to water loss through sweating. Rapid loss of body weight in the early stages of a diet is due mainly to body-water relationship changes. The rate at which weight is lost will gradually decrease later as body fat losses are the main reason for weight loss. Sometimes there may not be a significant weight loss in the early stages of an exercise program – though there may be significant changes in body composition (eg. decrease in body fat).

Aerobic exercise can increase energy use – but losing significant body fat through exercise involves months not days. Aerobic weight reduction exercise needs to involve larger muscles (eg. legs and arms).

OVERWEIGHT PEOPLE

In western society, people are well aware of the disadvantages of being overweight – not only for sport, but in general. This course deals with sports nutrition, and this chapter only with reducing weight in athletes. In general, athletes will not be obese, and they will be accustomed to a certain level of physical exertion. If the athlete is obese, however, and/or if they do not regularly exert themselves, then a weight loss program should be carried out under medical supervision.

WEIGHT CHANGE AND VERY LOW ENERGY DIETS

As already noted, athletes should aim to lose weight well away from competition time. This also applies to weight gain. When losing weight, smaller energy intake can reduce nutrient intake and sporting performance. In addition, the athlete may not lose just fat – they may lose muscle mass, which can adversely affect sporting performance. Very low calorie diets can lead to greater protein losses, whereas more gradual weight loss will conserve protein stores. If athletes are on a very low energy diet, they may suffer poor health. Female athletes are particularly vulnerable. Low energy intake and high energy output in women can lead to altered secretion of pituitary gonadotropins. This results in changes to ovarian hormonal secretions, which can lead to cessation of menstruation and poor bone mass in young women. Men may also experience altered hormonal secretions. Thus it is important to make sure that the energy deficit is only small, and closely monitored.

TIPS FOR LOSING BODY FAT

There are no magic pills or potions that have been proven to make people lose weight. To lose body fat, the athlete will need a combination of determination, support, and accurate information. Tips for losing body fat:

• Firstly, be sure that the athlete actually does need to lose weight

• Set down a plan for realistic weight loss – about 0.5 kg per week is a sensible goal for most people (this will not be the correct goal for all people). Set down both short and long term goals. What does the athlete want to weigh, and how long do they want to give themselves to achieve their goal? What is the maximum weight the athlete would find acceptable? What did they weigh when they achieved their best performances?

• When setting a long term weight goal, consult with a professional such as a nutritionist or sports scientist. Too many athletes will have an unrealistic goal in mind.

• Do not undertake weight loss programs close to competition, or when the athlete is under any other kind of pressure. In itself, weight loss is a pressure on the body, and it may adversely affect competition performance.

• If the athlete’s training is primarily skills based, or if the athlete is fairly inactive between training sessions, it may be possible to slot aerobic exercise into their program without harm. If the athlete is very inactive, then medical advice should be sought before commencing a program of exercise and/or weight reduction.

• Get the athlete to keep a food diary for a week – detailing everything they eat and the quantity. The athlete may be surprised at the amount and/or fat content of the food they are eating. The food diary will give an insight into how to get the athlete to lose weight.

• Basically, the intake of energy needs to be reduced to a level that will produce a weight loss but that still insures adequate food and nutrient intake to meet the athlete’s needs. So, the athlete will no longer be in energy balance – they will be expending more than they take in. Athletes should not reduce their energy intake below 1200-1500 kcal per day without professional advice. If they are, then a multi-vitamin/mineral supplement may be useful to help reduce the likelihood of deficiency. Meals should not be omitted, and food should be consumed in small quantities throughout the day to avoid hunger and increase the likelihood of the athlete sticking to the program.

• Reduce the athlete’s intake of saturated fats and oils. This can be done by eating only low fat meats (remove fat and skin from all meat consumed), using low fat dairy products, reducing use of margarines, butters and dressings, educating the athlete about low fat cookery, and by allowing the athlete to occasionally indulge in a treat (this reduces the likelihood of a binge on high saturated fat foods). Reducing fat intake alone will not insure weight loss. The athlete needs to intake less calories than they use.

• Avoid alcohol and sugary foods such as soft drinks. There will be instances where a high carbohydrate sports drink is used to recover after training, for example – but limit consumption otherwise. Focus on bulkier, more satisfying carbohydrates.

• Focus on high nutrient foods, so that the athlete can still maintain their nutrient needs without taking in too much energy.

• Dieting athletes need to consume a variety of fluids – especially water. Dehydration is not a valid way to lose weight in the long term, and it can be dangerous for athletes to become dehydrated.

• Get the athlete to identify when they eat poorly – is it at social events, or perhaps when they are tired or depressed? Behavioural modification such as distraction may be necessary.

• Eating should be slow and satisfying, not “on the run”. Make sure the athlete gets to enjoy proper meals, and that they are not constantly hungry. Some hunger is inevitable, but small regular snacks will decrease the likelihood of an eating binge.

• Education is the key – athletes need to understand the principles behind their diet, and should be taught long term healthy eating habits, rather than how to lose weight in a crash diet.

KEY CHARACTERISTICS OF A SAFE WEIGHT REDUCTION DIET

1. The diet must introduce a calorie deficit, yet supply all necessary nutrients to the athlete

2. The diet should incorporate a wide range of foods that stop the athlete getting bored, and keep hunger under control

3. The diet should be suited to the athlete’s lifestyle – a busy athlete does not want to spend hours cooking meals

4. The diet should allow for slow, gradual weight loss

5. The diet should be based on sound nutritional principles that can be adhered to over the athlete’s entire lifetime.

EATING DISORDERS

There are many types of eating disorders. The three most widely known ones are:

Anorexia nervosa

Anorexia nervosa is usually characterised by:

• an intense and irrational fear of body fat and weight gain even when markedly underweight

• an irrational determination to become thinner

• an altered perception of body weight and shape – so that the sufferer sees a "fat" person even when they are emaciated.

Bulimia nervosa

Bulimia is usually characterised by cycles of binge eating and purging. The sufferer will consume large amounts of food rapidly (or what they perceive is a large amount) in an automatic and fairly helpless manner. This can create physical discomfort and anxiety about becoming fat. They will then purge themselves by vomiting (induced), laxative use, enemas, diuretics, excessive exercise, fasting and dieting.

Anorexia athletica

Anorexia athletica sufferers are usually preoccupied with food and weight. They will exercise compulsively whilst attempting to control weight and attain a sense of power, control, and self respect.

CONVERSION OF METRIC AND ENGLISH UNITS

The following tables can be used to convert between the English and Metric systems of measurement

Weight