Myths of Aerobic Exercise and Weight Control Part II

In our previous post, we talked about the myths and facts of aerobic exercise and weight control versus . On part II, we will expand on them an complement the information. We hope you find it useful:

Myth: Muscles will turn into fat when you stop exercising.

Fact: Muscles can not turn into fat. Muscle and fat are two different and distinct tissues. They simply do not have the physical capability to change from one type of tissue to another. In reality, muscles have the unique property of ‘use me or lose me’. If you do not use a muscle, it will literally waste away (atrophy). This process is best illustrated when someone has to wear a cast on a broken leg. When the cast is eventually removed, the relatively unused leg muscles are considerably smaller than they were prior to the injury.

Myth: Performing aerobic exercise at a low rather than high intensity promotes a greater loss of body fat.

Fact: It is true that the lower the intensity level at which you exercise, the more the body prefers to use fats rather than carbohydrates as fuel. The major factor that determines the role of fat as  substrate during exercise is its ability to the muscle cell. In order to be metabolized, body fat (triglycerides) must be degraded into three molecules of free fatty acids and one molecule of glycerol. This splitting allows the free fatty acids to be converted to acetyl-CoA and enter the Krebs cycle. Hence, if fat is not available to the muscle cell then it can not be metabolized. Fat can only be metabolized via Krebs cycle oxidation.

Myth: Aerobic exercise suppresses your appetite.

Fact: The vast majority of studies that investigated the relationship between exercise and appetite have demonstrated that your level of caloric intake is usually unchanged or slightly increase in response to long-term aerobic exercise training. Your energy (caloric) intake, however, is usually increased to a level below your increase in energy expenditure. This results in a negative energy balance (i.e., energy expenditure greater than energy intake) and a loss of bodyweight and body fat. Some evidence exists that if you vigorously exercise before you eat, you will actually eat less because of an increase in body temperature and an alteration in hormone levels. The centers for the thermoregulatory system, appetite, and sleep lie right next to each other in your brain stem. When you affect one, you tend to affect the others.

Myth: Losing weight is extremely difficult.

Fact: Statistics indicate that during any given time period, approximately one-quarter of all men and one-half of all women in the United States are dieting to lose weight. For the majority of these individuals, losing weight is not the problem. Losing weight, for most people, is relatively easy. Keeping it off is their ever-present challenge. Estimates indicate 75% to 90% of all dieters who lose weight can expect to regain all of the weight they lost within one to three years of completing the diet. The tendency for weight regain among dieters is not only demoralizing, it also can be very hazardous to your health.

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