Written by Marthe Forcade

The safety of intermittent fasting, a common strategy for losing weight by restricting food intake to specific times, has been called into question by surprising findings from a study presented at a medical conference.

A study released Monday in Chicago found that restricting eating time to just eight hours a day increases the risk of death from heart disease by 91 percent. The American Heart Association released only an abstract, leaving scientists guessing about the details of the study protocol. The AHA said the study was reviewed by other experts before publication.

Lifestyle interventions aimed at weight loss are gaining attention as new generations of drugs help reduce weight. Some doctors questioned the study’s results, saying the results were skewed by differences such as underlying heart health between the fasting patients and a comparison group that ate for 12 to 16 days a day. He said it was possible. time.

Keith Fullen, emeritus professor of human metabolism at the University of Oxford, said in a statement to the UK Science Media Center that “time-restricted eating is a popular means of reducing caloric intake.” . “This study is very important in demonstrating the need for long-term research into the effects of this habit. However, this summary leaves many questions unanswered.”

Researchers led by Victor Zhong of the Shanghai Jiao Tong University School of Medicine analyzed data from about 20,000 adults who participated in the U.S. Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey.

The study looked at survey responses along with mortality data from 2003 to 2019. Because the study relied in part on a form asking patients to recall what they ate over a two-day period, the scientists said there was room for potential inaccuracy. Approximately half of the patients were male, with an average age of 48 years.

Zhong said it was not clear how long the patients had been on intermittent fasting, but researchers had assumed that they had been doing so.

She said in an email that fasting patients were more likely to be young men with a higher body mass index and food insecurity. They also had lower rates of hypertension, diabetes, and cardiovascular disease, according to his self-reports. “Although we controlled for all these variables in our analysis, the positive association between the 8-hour time-restricted diet and cardiovascular mortality remained,” Zhong said.

This abstract was presented at the AHA Lifestyle Science Sessions meeting in Chicago.