Many religious groups incorporate periods of fasting into their rituals, though the focus there tends to be more spiritual than health-oriented: Muslims fast from dawn until dusk during the month of Ramadan, Christians, Jews, Buddhists, and Hindus who traditionally fast on designated days of the week or calendar year.

Key researchers who study fasting aren’t focusing on weight loss at all. In fact, many of the studies on fasting come from institutes of aging and the researchers behind the studies actually focus on longevity and disease prevention. Weight loss is seen as a bonus.

• Restricting your calorie intake for prolonged periods of time may lead to lower overall energy intake and weight reduction.
• The body shifts into a fat-burning mode when it doesn’t get food for an extended period of time.
• People don’t always lose weight on fasting diets. And they don’t necessarily lose more than on plain, old calorie-restriction diets.

Many people can’t stick to fasting diets long enough to keep the weight off. Thus, dropout rates have been as high as 40 percent.

Despite the statistical significance of weight loss results, the clinical significance and practicality of sustaining intermittent fasting are questionable.

Patients with eating disorders do best when they eat regular meals and snacks.

Intermittent restriction of intake is often one of the behaviors that people with eating disorders engage in as part of their eating disorder and it often sets them up to binge and/or purge.