A recent comprehensive study of 20,000 adults suggests that time-restricted eating, a form of intermittent fasting, may significantly increase the risk of death. Moreover, healthy eating habits could challenge the established scientific consensus on this topic.

The latest research, published by the American Heart Association, reveals that restricting eating to less than eight hours a day is associated with a staggering 91 percent increase in the risk of death from cardiovascular disease.

After analyzing participants’ dietary habits and health over a period of up to 17 years, the study found no evidence to support the idea that limiting meals to an eight-hour window reduces the risk of death from any cause.

Lead author Professor Victor Wenze Zhong expressed surprise at the results, stating to BBC Science Focus that they had anticipated a decrease in cardiovascular disease risk and overall mortality with long-term adoption of an eight-hour time-restricted diet.

He further stated, “Despite the popularity of this dietary approach for its short-term benefits, our study indicates that while the typical eating window ranges from 12 to 16 hours per day, shorter meal times do not correlate with longer life.”

Although the precise reason why time-restricted eating may increase the risk of cardiovascular death is still unknown, one possible explanation suggested by Zhong is that it could lead to a loss of muscle mass.

Recent interest in time-restricted eating has been fueled by its potential health benefits. Prior studies have indicated that it could aid weight loss and improve blood sugar and cholesterol levels.

Many practitioners follow a 16:8 schedule, whereby they consume all food within an eight-hour window and fast for the remaining 16 hours.

This eating pattern aligns more closely with natural circadian rhythms and is believed to support better sleep and metabolic function. However, the recent findings cast doubt on its long-term benefits.

Stanford University School of Medicine Professor Dr. Christopher Gardner cautioned that while time-restricted eating may offer short-term advantages, it could have adverse long-term effects, based on the study.

It is important to note that the study has not yet undergone peer review, and detailed dietary information of the participants is not available.

The research population, with an average age of 49, recorded 2797 deaths, of which 840 were due to cardiovascular disease.

As per Zhong, individuals, especially those with existing heart disease or cancer, should be cautious about adopting an eight-hour eating window due to its associated increased risk of cardiovascular death.

He emphasized the potential effectiveness of intermittent fasting for short periods, such as three to six months, for weight loss and cardiometabolic health improvement. However, long-term adherence to practices like eight-hour time-restricted eating warrants careful consideration.

Despite these cautionary findings, Zhong and Gardner noted that it is premature to draw definitive conclusions regarding time-restricted eating based on a single study.

Ultimately, the study suggests that the content of one’s diet may hold greater importance than the timing of meals for long-term health outcomes.

About our experts:

Dr. Victor Wenze Zhong is a professor and chair of the Department of Epidemiology and Biostatistics at the School of Medicine, Shanghai Jiao Tong University. He holds leadership roles in the American Academy of Nutrition and the American Heart Association.

Dr. Christopher Gardner is a professor of medicine at Stanford University, known for his research on dietary components and patterns. He has served on the American Heart Association Nutrition Committee and the Lifestyle & Metabolic Health Council.