Fasting—defined as reducing or eliminating your calorie intake for a set period of time—has often been cited as a great way to lose weight and keep pounds off. But there are lots of different ways to fast, from a once-a-week pause to the month-long daytime fast often done in a religious context. So far one method hasn’t really stood out above the rest, although researchers are starting to hone in on one approach: intermittent fasting.
Intermittent fasting has shown the most promise for boosting metabolism and burning fat, according to a new study published in the journal Cell Research. Researchers put mice on a 16-week intermittent fasting program. The mice ate normally for two days, and then went one whole day without food. Meanwhile, a control group of mice ate the same amount of calories overall, just spread evenly across three days.
After four months, the fasted mice tended to have lower bodyweights than the control-group mice. They also had less white fat and more brown fat, which is used for energy and body heat, and their insulin and glucose levels were more constant.
So: Why does intermittent fasting work? It's possible that intermittent fasting stimulates an anti-inflammatory cell, which then triggers an increase in production of a blood vessel growth factor, which in turn leads the body to burn more fat cells, according to the researchers.
"Intermittent fasting without a reduction in calorie intake can be a preventative and therapeutic approach against obesity and metabolic disorders," said study co-author Kyoung-Han Kim, an assistant professor in the department of cellular and molecular medicine at the University of Ottawa. "Strikingly, these fasting-stimulated changes in the growth of vascular cells and subsequent immune alterations occur even after a single cycle of 24-hour fasting, and are completely reversed when mice start eating again."
Just remember: You don't have to starve yourself to lose weight.