People in cultures around the globe have been fasting for spiritual and health reasons for hundreds, if not thousands, of years. Fasting for weight loss, however, is a more recent phenomenon. The jury’s out on whether fasting is a safe and effective tool for weight loss, but most medical experts think it is not.
Even doctors who recommend fasting for health purposes think fasting to lose weight is a bad idea. When you fast your metabolism slows down, they explain. Since the metabolism is the body’s mechanism for burning calories, a slower metabolism means the body uses up calories more slowly—the exact opposite of what needs to happen in order to lose weight. When you fast you lose a lot of water weight quickly. But because your metabolism has slowed down, when you start eating food again, even healthy food, your body can’t burn the calories quickly enough, so you gain weight. Most people gain back the weight they lost during fasting, and many gain even more weight.
According to some doctors and other medical experts, fasting to lose weight can cause serious health problems. Fasting for even a day or two can be dangerous for people who have liver or kidney problems, have diabetes, have compromised immune systems, or are on certain medications.
Weight loss plans that involve fasting often also use enemas or laxatives for detoxification. Doctors cite many risks from detoxing diets, including dehydration, heart palpitations, nutrient deficiencies, and electrolyte imbalance. Professionals who treat eating disorders share a concern that people with eating disorders, or with the tendency toward eating disorders, may abuse the fasting laxatives in order to reach an unhealthy weight.
Medical Benefits of Fasting
An increasing number of physicians are seeing a role for fasting in medical treatments when done under medical supervision. They cite a number of application for fasting, such as:
- Fasting before surgery reduces the burden on the digestive system;
- Fasting before medical tests, such as cholesterol and blood glucose levels, yields more accurate results.
- Fasting may be effective treatment for health conditions such as arthritis, heart disease, colitis, psoriasis, eczema, high blood pressure, autoimmune diseases, and depression.
- Fasting has been found to relieve stress and help people take control of their lives.
Most healthy people will not suffer from fasting for a day or two. Some people, however, should not fast at all, experts say. The list of people who should not fast includes pregnant women, women who are breastfeeding, people with certain chronic diseases, people with malnutrition or wasting diseases, children, the elderly, people with a history of cardiac arrhythmia, and individuals with liver or kidney disease.
Examples of Diets for Fasting for Weight Loss
Except in extreme situations fasting does not mean consuming nothing. Most weight-loss fasts involve eating or drinking a limited amount of specific foods or beverages. Following are a few examples of weight-loss fasts.
Water fasting. Dieters drink two or more quarts of water a day. A squeeze or lemon juice or lime juice can be added to the water. The recommendation is to start with one 24-hour period, and then add intermittent 24-hour fasts.
Juice fasting. Dieters drink 32-to-64 ounces of juice per day, plus water, for three-to-seven days. They drink one or two 8-ounce glasses of fresh (preferably organic) fruit juice or vegetable juice instead of solid food for lunch and for dinner. They drink cool distilled, spring, or filtered water the rest of the day.
Intermittent fasting. With intermittent fasting dieters alternate between periods of water fasting and periods of non-fasting. Alternate day fasting is a type of intermittent fasting in which a person fasts for 24 hours then goes off the fast for 24 hours.
Master cleanse. The master cleanse or lemonade diet is a juice fast combined with detoxification. The lemonade is a combination of maple syrup, cayenne pepper, lemon juice, and water. A typical master cleanse fast lasts ten days, but people often stay on this fast for longer.
Daily fast. Finish eating dinner by 6 or 7 p.m.; then do not eat again until breakfast. This daily fast gives a 12- to 14-hour daily fast. Typically used for cleansing the body, the daily fast can be a tool for safe weight loss when combined with a healthy diet and regular exercise.
With all fasts, whether for weight loss or other purposes, it is important to reduce eating gradually before the fast and start eating again gradually after the fast, introducing new foods slowly.
The Bottom Line
While many programs tout the benefits of fasting for weight loss, most medical and nutrition experts believe that fasting is not effective for long-term weight control. Many are concerned about the serious health problems that may accompany fasting. The consensus is that the risks of fasting for weight loss far outweigh any possible benefits.
What do doctors recommend for weight loss? A balanced diet that includes lots of fruits and vegetables, whole grains, lean protein, reduced-fat dairy products, and plenty of water. A healthy diet of at least 1,200 calories a day plus regular physical activity is the recommended formula for successful and safe long term weight loss.
By following a weight loss program based on physical activity and healthy eating, individuals learn how to make healthy food choices and change unhealthy eating behaviors. Slow and steady changes mark success in the lifelong process of maintaining a healthy weight.
Anyone who is considering a weight loss fast should consult with a medical doctor before starting. A healthcare provider can assess the risks and benefits of fasting for each individual and may be able to make recommendations and referrals that lead to safer and more effective ways to shed pounds and maintain a healthy weight.