Fasting for weight loss is touted as a way to drop weight quickly and easily, without even needing to exercise. The truth is, in nearly all cases, fasting for weight loss is not safe for the body. In addition, the weight that is lost during a fasting period is often water weight, and may be gained right back the instant one resumes a normal diet. Fasting proponents believe that it cleanses the body, jump-starts weight loss, boosts energy, and improves the appearance of skin.
There are a number of different programs advertising fasting for weight loss; juice fasts are common, but there are a number of others that use ingredients such as honey, lemon or pepper, among others, as the sole source of nutrients for a day or more. Typically, true fasts where one is consuming nothing but liquids such as juice do not last more than one to three days, but fasts where participants may eat a small meal a day consisting of vegetables, fruits, or whole grains may last longer.
Fasts may also be labeled as detoxes or cleanses, claiming that toxins build up in the body, and need to be eliminated through this fasting process. This is largely unproven, and there is no reason to believe that the liver and kidneys do not satisfactorily detoxify the body. Fasts persist, however, and many people attempt to use fasting for weight loss despite the inherent dangers.
First, fasting for weight loss typically causes an upset stomach and diarrhea. If left untreated, this can lead to dehydration, which has the potential to become fatal. Dehydration might first cause dizziness, nausea, or fainting. It is important not to exercise when fasting; the body does not have the energy reserves, when fasting for weight loss, to increase the heart rate to a higher level and then recover. Blood sugar often drops when fasting as well.
An extended fast can lead to vitamin deficiencies and muscle breakdown. Fasting for weight loss does tend to cause rapid weight loss, but again, this weight is not lost in a healthy manner, and will generally just be gained right back after normal food is eaten again. If one is considering a fast or detoxification program, it is best to first check with a healthcare professional to be sure it is relatively safe. Young people, the elderly, pregnant women, and anyone with a medical condition should not fast.