Intermittent fasting (IF) has been a popular diet trend for over a decade, but a new comprehensive analysis suggests its weight loss benefits may be no greater than standard dietary approaches.
The study, a meta-analysis conducted by researchers affiliated with Cochrane, reviewed data from 22 randomized clinical trials involving 1,995 adults across North America, South America, Europe, China, and Australia. It included multiple types of intermittent fasting, such as alternate-day fasting, periodic fasting, and time-restricted eating.
Intermittent fasting typically limits calorie intake to specific windows of time, with popular methods including the 5:2 diet—eating normally five days a week and restricting calories on two days—and the 16:8 approach, which allows eating only during an eight-hour period each day. While previous studies have reported mixed results, this latest analysis found that IF led to only modest weight loss of 2–5% over 6–12 months compared with no diet, but this was not considered clinically significant.
“Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” said Luis Garegnani, the study’s lead author from Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre. “It may be a reasonable option for some people, but the current evidence doesn’t justify the enthusiasm we see on social media.”
Despite these findings, experts emphasize that the potential benefits of IF extend beyond weight loss. For instance, a 2023 study indicated that a six-hour eating window improved sleep and cognitive performance in mice, while a separate human study showed that the 16:8 diet improved long-term blood sugar levels in individuals with type 2 diabetes.
Adam Collins, associate professor of nutrition at the University of Surrey, who was not involved in the Cochrane research, said the study should not overshadow other research supporting intermittent fasting. “IF regimens can be an effective tool for weight management and may offer metabolic benefits that are independent of weight loss,” Collins noted. He highlighted that these approaches could support metabolic health, assist in the maintenance of weight after loss, and be useful for managing metabolic diseases.
As interest in intermittent fasting continues, experts suggest the conversation may shift from its weight loss potential to its broader metabolic effects, underscoring the diet’s evolving role in health management.
