Bodybuilding

Diets very low in calories (800 calories per day or fewer), including those that have been promoted as having a “protein-sparing effect” (conserving lean tissue), have often been associated with serious medical complications, including cardiac dysrhythmias (irregular heart rate that is sometimes intractable) and sudden death. Diets very low in calories Produce distinctive and abnormal electrocardiographic (ECG) rhythm patterns that are most likely a used by protein loss from the myocardium (heart muscle) or cell-membrane instability from rapid Weight loss.Stringent dieting is also considered a major trigger for binge eating. A 6-month experiment of healthy men who were put on a diet that provided about one half of their usual daily caloric intake resulted in massive eating binges in which the men ate up to five meals and 5000 calories a day until they had returned to their normal weight.

Another problem with very-law-calorie diets is that they cause an adaptive response that decreases energy expenditure and increases fat storage. Repeated dieting may lower BMR on a long-term basis.

Low-Calorie Diets

Low-calorie diets (800 to 1000 calories per day) result in atrophy of the heart muscle. When low­calorie diets are accompanied by regular exercise, the muscle loss is minimized, but it still occurs. However, regular exercise combined with a moderate-calorie diet results in loss of body weight and gain of cardiac muscle. Exercise-induced cardiac hypertrophy results in a stronger, more efficient heart.

Low-Fat Diets

Low-fat diets are potentially effective techniques for losing weight. With its high-caloric yield, low thermic effect, and almost unlimited capacity for storage, fat is a major threat to weight maintenance. Consequently the current fixation is on “fat-free” or “low-fat” foods. The assumption is that if a food is low in fat, it is also low in calories. Only 7% of Americans are concerned about calories, compared with 60% who cite fat as public enemy number 1.27 As a result, although Americans are consuming less fat calories percentage-wise, they are consuming more total calories from all sources and are getting heavier. (Actual fat intake remains the same as it was during the past 10 years. Percentage-wise, it dropped from 36% to 34% because of an increase in total calories consumed. )

Low-fat diets have not been effective for many dieters because the dieters have become volume eaters. Researchers at Pennsylvania State University demonstrated this point when on separate days they gave women one of three types of yogurt: low fat, low calorie; low fat, high calorie; and high fat, high calorie. The low-fat, high-calorie and high-fat, high­calorie yogurts contained the same number of total calories. Half of these yogurts were labeled either low fat or high fat; the other half were unmarked. Thirty minutes after consuming the yogurt, the women ate lunch. The women who ate the yogurt labeled low fat compensated by taking in more calories during lunch even if they ate the low-fat, high­calorie version. The women who ate the unlabeled yogurt, on the other hand, ate fewer calories at lunch after eating the high-calorie version. The researchers concluded that when the women ate yogurt labeled low fat, they rationalized that they could indulge more at lunch. But when they were given unlabeled yogurt, they were more tuned in to their bodies’ physical cues and naturally adjusted the amount they ate.

The attitude that people can eat what they want, in unlimited quantities, as long as it’s fat free is wrong. Calories do count. Fat-free foods can help people lose weight if they are used properly, if they don’t result in over compensatory consumption of food, and if total calories are kept in line.

Popular Diets

Many diets on the market are nutritionally sound, and many are not. Some are potentially hazardous, and many are based on faulty nutritional and physiological concepts. Some require that food be eaten in a certain order and severely restrict allowable foods. Diets such as Jenny Craig come in pre measured servings. Some require medical supervision. Others impose unrealistic demands on caloric restrictions, and still others make promises based more on fantasy than facts. The Food and Drug Administration (FDA) does not investigate every new fad diet, and many diet plans are published without the FDA’s endorsement. If a diet is published, it is usually because a publisher sees potential profits from its sales. Publishers know that the advice to “eat less fat and increase physical activity” will not sell books but fad diets with secret ingredients or magic formulas will.

Because fad diets are unlikely to disappear, identifying some of the characteristics and marketing strategies used by diet promoters to appeal to unwitting consumers is helpful:

• They promote quick results.
• They stress eating one type of food to the exclusion of others.
• They emphasize gimmick approaches, such as eating food in a particular order.
• They cite anecdotes and testimonials, usually involving well-known people.
• They claim to be a panacea for everyone. They often promote a secret ingredient.
• They often recommend expensive supplements.
• They rarely emphasize permanent changes in eating habits.
• They usually show little concern for accepted principles of good nutrition . They are usually cynical of the evidence that comes from the scientific community.

In general, dieting is an ineffective weight­management method. The expectation that temporary changes in eating habits will lead to permanent weight loss is unrealistic. Sensible and permanent dietary changes that depend on wise food choices are an excellent way to cut calories and a healthy way to eat.

To maintain weight, caloric intake must be balanced by caloric expenditure. To lose weight an individual has to achieve a caloric deficit in which the number of calories burned exceeds the number of calories consumed. This is the basic principle of weight management. As such, it is simple, straight forward, and includes three obvious strategies -(1) Restricting caloric intake by dieting

(2) Increasing caloric expenditure through physical activity

(3) A combination of dieting and physical activity. What is not so easy to explain is how two people can respond so differently to dieting and exercise weight loss strategies. Complex forces, many of which are still not clearly understood, influence the success of weight-management/weight-loss efforts.

Dieting

Statistics show that dieting is the method of choice for most Americans trying to lose weight. Although dieting usually works only temporarily, most people who have failed to maintain weight loss are willing to try again. Many people seek the miraculous diet that will transform them from fat to thin, preferably with minimal effort and in the shortest time possible.

The success rate of diet only strategies is dismal. In its review of organized weight-loss programs, the NIB found that within 1 year dieters gained back between one third and two thirds of the lost weight; within 5 years they regained nearly all of it. 23 Only 5% of all dieters are successful in reducing to a target weight and maintaining that weight for more than 5 years. Maintaining post diet weight is one of the major failures of weight loss through dieting because dieters do not learn the habits and behaviors needed to remain at the new weight. As a result they lose and regain weight many times in their lives. This pattern of repeated weight loss and gain, known as weight cycling, yo-yo dieting, and seesaw approaches to weight loss, is potentially harmful and counterproductive.

In a review of the literature throughout 1991 on weight cycling, Wing 29 concluded that contrary to popular opinion there did not appear to be any negative effects of cycle dieting on total body fat, the distribution of fat, or metabolism. Subsequent efforts to lose weight also appeared to be unaffected. However, evidence suggests that weight cycling increases the risk of death, especially from cardiovascular conditions.

Researchers at Harvard University 30 studied data on 11,703 subjects over 30 years to see whether weight cycling had any effect on longevity. As expected, those whose weight remained stable had a lower mortality rate. However, those who lost weight were more likely to die than those who gained weight. Men who gained more than 11 pounds were 36% more likely to die than those whose weight remained stable. The men who lost more than 11 pounds, however, had a 57% higher chance of dying. The explanation proposed was that those who had lost 11 pounds over the decade had actually gained and lost an average of 100 pounds over their lifetimes. The stress of yo-yo dieting contributed to the higher death rates. However, with the high recidivism rate of dieters, the researchers concluded that it is probably better to remain slightly overweight than to weight cycle. Exceptions are people whose excessive body weight increases their risk for diabetes, high blood pressure, and high cholesterol levels. In a 1994 report of 43 studies on the effects of weight cycling, researchers concluded that the health gains from a weight loss of as little as 5 to 10 pounds, even if it is temporary, out­weighs the hazards of weight cycling for people with a history of these chronic conditions. Still, experts agree that it is better to lose weight and keep it off.

A number of the physiological and psychological symptoms and signs of overreaching/overstraining have been suggested to be partly due to a chronic energy deficit, an inadequate availability of specific nutrients, or both. This may affect the body’s response to intensified training. The following describes some of the general dietary strategies that athletes can use to prevent over training.

Energy Intake

The first nutritional strategy to prevent overstraining is to make sure that athletes consume enough calories to offset energy demands or maintain energy balance. Daily caloric intake for untrained individuals typically ranges between 1900 to 3000 kcal’s/day (i.e., 25 to 45 kcal’s/kg/day for a 70-kg person) . Exercise training obviously increases energy expenditure. The longer and more intense an athlete exercises, the greater the energy expenditure. Energy expenditure estimates for athletes have ranged from 3500 kcal’s/day (50 kcal’s/kg/day) for individuals training 30 to 60 min/day up to 12,000 kcal’s/day (i.e., 170 kcal’s/ kg/day) for cyclists competing in the Tour de France (cycling 4 to 6 hrs/day). For most high school and college athletes training 2-2.5 hrs/day, energy expenditure estimates range between 60 to 80 kcal/kg/day. Despite this energy requirement, athletes often do not consume enough calories to offset energy demands. This may result in a chronic deficit in energy intake and has been implicated as one potential causative factor to overstraining.

Athletes particularly susceptible to maintaining negative energy intakes during training include runners, cyclists, swimmers, triathletes, gymnasts, skaters, dancers, wrestlers, and boxers Additionally, female athletes have been reported to have a high incidence of eating disorders. Consequently, the parent and/or coach should ensure that athletes are well fed and consume enough calories to offset the increased energy demands of training. Although this sounds relatively simple, intense training often suppresses appetite and/or alters hunger patterns Some athletes do not like to exercise within several hours after eating because of sensations of fullness and/or a predisposition to cause gastrointestinal distress. Further, travel and training schedules may limit food availability and/or the types of food athletes are accustomed to eating. This means that care should be taken to plan meal times in concert with training as well as make sure athletes have sufficient availability of nutrient-dense foods throughout the day for snacking between meals (e.g., drinks, fruit, carbohydrate/protein bars, etc.).

Macronutrient Intake Guidelines

The second nutritional strategy to prevent overtraining is to ensure that athletes consume the proper amounts of carbohydrate, protein, and fat in their diet. Research has indicated that athletes should ingest between 8 to 10 g/day of carbohydrate during intense periods of training to help maintain carbohydrate stores. To do so, athletes are recommended to eat frequently (e.g., 4 to 6 meals per day) and ingest high-calorie carbohydrate foods and/or concentrated carbohydrate drinks. Preferably, the majority of dietary carbohydrate should come from complex carbohydrates with a low to moderate glycemic index (e.g., grains, starches, fruit, maltodextrins, etc.).

There has been considerable debate regarcing protein needs of athletes. Initially, it was recommended that athletes do not need to ingest more than the RDA for protein (i.e., 0.8 to 1.0 g/kg/day for children, adolescents, and adults). However, research over the last decade has indicated that athletes engaged in intense training need to ingest about times the RDA of protein in their diet 0.5 to 2.0 g/kg/day) to maintain protein balance. If an insufficient amount of protein is obtained from the diet, an athlete will maintain a negative nitrogen balance which can increase protein catabolism and slow recovery. Over time, this may lead to lean muscle wasting and training intolerance.

Although most athletes ingest this amount of protein in their normal diet, there are some athletes who are susceptible to protein malnutrition (e.g., runners, cyclists, swimmers, triathletes, gymnasts, dancers, skaters, wrestlers, boxers, etc.). Therefore, care should be taken to ensure that these types of athletes consume a sufficient amount of quality protein in their diet to maintain nitrogen balance (e.g., 1.5 to 2 g/kg/day). The best sources of low-fat quality protein are white-meat skinless chicken, fish, egg white, and skim milk proteins (caseine and whey). On the other hand, research has also indicated that ingesting more protein than necessary to maintain nitrogen balance does not promote greater gains in strength or muscle mass. Consequently, athletes do not need to ingest excessive amounts of protein to promote gains in strength and muscle mass during training.

The dietary recommendations of fat intake for athletes are similar to those recommended for nonathletes to promote health. Generally, athletes should consume less than 30% of their daily caloric intake as fat. For athletes attempting to decrease body fat, it is also recommended that they consume 0.5 to 1 g/kg/day of fat. The reason for this is that weight loss studies indicate that people who are most successful in losing weight and maintaining the weight loss are those who ingest less than 40 g/day of fat in their diet. Strategies to help athletes manage dietary fat intake include teaching them which foods contain fat so that they can make better food choices and how to count fat grams.

Strategic Eating

In addition to the general nutritional guidelines described above, research has also demonstrated that timing and composition of meals consumed may playa role in preventing overtraining. In this regard, it takes about 4 hours for carbohydrate to be digested and begin to be stored as muscle and liver glycogen. Consequently, pre-exercise meals should be consumed about 4 to 6 hours before exercise. This means that if an athlete trains in the afternoon, breakfast is the most important meal to top off muscle and liver glycogen levels. Research has also indicated that ingesting a light carbohydrate and protein snack 30 to 60 minutes before exercise (e.g., 50 g of carbohydrate and 5 to 10 g of protein) serves to increase carbohydrate availability toward the end of an intense exercise bout. This also serves to increase availability of amino acids and decrease exercise-induced catabolism of protein.

When exercise lasts more than 1 hour, athletes should ingest glucose/electrolyte solution (GES) drinks to maintain blood glucose levels, help prevent dehydration, and reduce the immunosuppressive effects of intense exercise. Following intense exercise, athletes should consume carbohydrate and protein (e.g., 1 g/kg of carbohydrate and 0.5 g/kg of protein) within 30 minutes after exercise as well as consume a high-carbohydrate meal within 2 hours following exercise. This nutritional strategy has been found to accelerate glycogen resynthesis and promote a more anabolic hormonal profile that may hasten recovery. Finally, for 2 to 3 days before competition, athletes should taper training by 30-50% and consume 200 to 300 g/day of extra carbohydrate in their diet. This carbohydrate loading technique has been shown to supersaturate carbohydrate stores before competition and improve endurance exercise capacity. Thus, the type of meal and timing of eating are important factors in maintaining carbohydrate availability during training and potentially decreasing the incidence of overtraining.

During prolonged exercise, athletes become fatigued. For many years, exercise scientists believed that fatigue was simply related to peripheral muscle glycogen depletion and perhaps the hypoglycemia which may occur during prolonged exercise. However, more recent studies indicated that athletes fatigue even though blood glucose levels were maintained during exercise and a sufficient amount of glycogen was available in the muscle. These findings suggested that fatigue could not simply be explained by peripheral adaptations but that other factors may be involved in the fatigue process during prolonged exercise. The potential role that central fatigue may play in overtraining, and dietary strategies that may help delay central fatigue.

Central Fatigue Hypothesis

Newsholme, Blomstrand, and colleagues initially advanced the theory that fatigue during prolonged exercise may be partly related to exercise-induced alterations in the central nervous system. The theory suggests that as muscle glycogen levels decline during exercise, there is an increased oxidation of fat and the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine as fuel substrates. As a result, free fatty acid (FFA) levels in the blood gradually increase while the availability of BCAAs in the blood decreases. The increase in FFA levels in the blood is accompanied by a release of the amino acid tryptophan from albumin, serving to increase the level of free tryptophan in the blood. The result is that as one exercises, the ratio of free tryptophan to BCAA steadily increases.

Increases in the ratio of free tryptophan to BCAA have been shown to increase the entry of tryptophan into the brain. Increased concentrations of tryptophan in the brain have been reported to promote the formation of the neurotransmitter beta-hydroxytryptamine (serotonin). Increased levels of serotonin in the brain and peripheral tissues have been reported to induce sleep, depress motor neuron excitability, influence autonomic and endocrine function, and suppress appetite in animal and human studies. Consequently, an exercise-induced imbalance in the ratio of free tryptophan to BCAA has been implicated as a possible cause of acute physiological and psychological fatigue (central fatigue). It has also been hypothesized that chronic elevations in serotonin levels, which may occur in athletes who overtrain, may explain some of the reported signs and symptoms of the overtraining.

Although the central fatigue theory seems straightfor­ward, there has been debate in the scientific community regarding the validity of the hypothesis. Segura and Ventura hypothesized that the increase in the free tryptophan to BCAA ratio may help to decrease the perception of pain, thus improving exercise performance by increasing the pain threshold. However, given the most recent research there is more sound scientific evidence to support the theory that central influences during exercise may play a role in the onset of fatigue under certain conditions. However, because the potential causes of overtraining are multifaceted and have yet to be fully understood, the degree to which central fatigue may contribute to overreaching and/or overtraining remains to be determined.

Nutritional Needs of the Immune System:

Although moderate exercise has been reported to enhance immunity, intense prolonged exercise has been found to temporarily suppress the immune system. For example, research has indicated that following intense exercise, the immune system may be depressed for as long as 6 hours. This open window of suppressed immune function may allow the body to be more susceptible to acquiring host infections. To support this theory, several studies have reported that following intense exercise like a marathon, athletes have a greater incidence of upper respiratory tract infections (URTIs) for several weeks following the event. Additionally, athletes who overreach and/or overtrain often get URTIs, ear infections, and/or colds. This suggests that athletes who train too often or too intensely may experience a chronically suppressed immune system.

The primary metabolic fuel for the lymphocyte is glutamine. The availability of glutamine affects lymphocytic function. In this regard, in vitro and in vivo, evidence suggests that increasing the availability of glutamine enhances immune function while decreasing glutamine levels suppresses immune function. During high­intensity intermittent and prolonged exercise, it has been suggested that glutamine levels decline in the blood. The reason for this is that glutamine, like BCAAs, readily serves as a metabolic substrate during exercise. The exercise-induced hypoglutaminia has been reported to last up to 6 hours following high-intensity intermittent exercise. Moreover, some overtrained athletes have been reported to have chronically low glutamine levels Consequently, one theory of exercise-induced immuno-suppression is that decreased glutamine availability following exercise may serve to suppress lymphocytic function, making it more difficult to respond to immune challenges. Athletes involved in periods of intensified training that often involves training more than once per day may therefore be more susceptible to a hypoglutaminia-induced immunosuppression.