If you've packed on the COVID 15 (or 20, or 30) you're probably hungry for new ways to take those excess pounds off. One weight loss strategy that's been lauded for several years now is intermittent fasting, an eating pattern that cycles between times of, well, fasting and eating. “While many diets focus on what to eat, intermittent fasting is really all about when you eat,” says Louis Aronne, M.D., director of the Comprehensive Weight Control Center at Weill Cornell Medicine in New York City. There are two main approaches, he notes: traditional intermittent fasting, where you eat normally five days a week, and either fast or sharply restrict calories on the other two, or time restricted eating, where you choose an eating window every day so that you leave a 14- to 16-hour overnight fast.
Initially, intermittent fasting was touted as the holy grail for weight loss, not only allowing you to shed girth but also protecting against chronic diseases such as type 2 diabetes, heart disease and even certain cancers. But while initial studies were promising, Aronne notes, new research suggests the approach is no more effective than a traditional low-calorie diet.
A new study calls fasting into question
A study published this past September in JAMA Internal Medicine followed 116 overweight adults who fasted for 16 hours a day and only ate between noon and 8 p.m. for three months and found that subjects didn't lose any more weight than a control group. “We found that it wasn't an effective tool for weight loss,” says study author Ethan Weiss, M.D., a cardiologist at the University of California, San Francisco, who notes that his research didn't show any improvement in metabolic markers such as blood cholesterol or blood glucose levels. This follows on the heels of earlier research that found intermittent fasting was no more effective than an old-fashioned low-calorie diet. A 2018 study published in the American Journal of Clinical Nutrition examined 150 overweight and obese patients over nearly a year, some of whom simply cut calories by 20 percent, while others followed a five-days-on/two-days-off pattern of intermittent fasting. At the end of the trial, both had lost similar amounts of weight and body fat.