Long-term fasting is difficult and can even be dangerous, but dropping your calorie count for four to five days every few months may fool your system into shedding belly fat, according to a 2015 study from the University of Southern California Longevity Institute, in Davis. People who consumed 34 to 54 percent fewer calories than normal (by drinking a specially formulated low-protein, low-sugar meal-replacement drink) for five continuous days a month and ate the way they usually did the other 25 days lost a significant amount of visceral fat after three months. "After a couple of days of [pseudo fasting], the body turns to stored abdominal fat for energy," says Valter Longo, Ph.D., a gerontologist and the lead study author. The study was done on just 38 people, but other research reveals similar benefits from alternate-day fasting—that is, eating as you normally would one day, dipping to around 500 calories the next day, and so on.
Following this strategy for two or more months can reduce visceral fat by 20 to 50 percent, according to ongoing research from the University of Illinois, Chicago. Not only does it reduce calorie intake but "every-other-day fasting also lowers cholesterol and insulin levels and staves off insulin resistance—all of which can reduce visceral fat," says study author Krista A. Varady, Ph.D., an associate professor of nutrition at the University of Illinois, Chicago. (Always get your doctor's OK before fasting.)