Fasting has been practiced for thousands of years, although early practice of fasting was used more as a religious ritual or a method of “cleansing” the body. Over the years, fasting has become a popular weight loss method. Although those who fast may see quick weight loss, the health risks far outweigh the benefits when using a fast to lose weight.
How Fasting Works
Fasting involves totally avoiding all food and consuming only water or juice for a period of time. Dieters may fast from anywhere between 2 to 9 days, and in extreme cases, up to 30 days. Fasting dieters typically have low energy levels and decrease activity levels to compensate for this lack of energy.
Fasting Health Risks
Muscle breakdown: The body’s main source of energy is glucose, which the body makes from food. During the first few hours of a fast, the body can draw energy from glucose that is stored in muscles and the liver. Once glycogen stores are used up and no food enters the body, blood sugar levels drop, and protein from muscle is broken down and turned to glucose that the body then uses as energy. As muscle breakdown occurs, important minerals are also depleted from the body such as potassium, sodium, and calcium, which has harmful effects on the body and can lead to death. This can directly impact your personal fitness.
Ketosis: When the body uses fat as energy instead of glucose, ketosis occurs. Ketosis is a harmful metabolic state in which ketones are formed. An increased amount of ketones in the blood can cause kidney failure, gout or kidney stones. Ketones can also decrease appetite, cause nausea, and bad breath.
Decreased brain functioning: The brain uses 50 percent of glucose in the body. When food is avoided and there is no longer any glucose for the body to use, the brain cannot function properly. Fasting dieters may experience confusion, dizziness, light-headedness, and poor concentration.
Increased risk of binge eating or overeating: As with any dieting method that requires deprivation, there is an increased risk of binge eating or overeating when food is re-introduced into the diet as the body tries to compensate for lack of nutrients.
Metabolism slow-down: During periods of food deprivation, the body uses conserved energy more slowly than when the body is fed regular meals. Also, body temperature tends to decrease during periods of deprivation, which is also a signal to the body to conserve energy stores, thereby causing a slow down in metabolism.
Weight is regained: Dieters who participate in fasting typically lose weight; however, this weight loss is short-lived as most of the weight loss is due to water loss and wasting muscle tissue. Once food is reintroduced, the weight lost will most likely be regained.
Fasting is appealing to those who need or want to lose weight quickly and is generally safe for a day or two for most healthy individuals; however, fasting as a way to lose weight has no scientific backing as far as safety and efficacy. Adults considering a fast should consult a physician before doing so.