Intermittent fasting tied to a higher risk of cardiovascular death, research shows 

March 20, 2024

Intermittent fasting — a diet that cycles between voluntary fasting and non-fasting periods — could be linked to a higher risk of dying from cardiovascular disease, according to a new analysis.

The analysis, first presented Monday at the American Heart Association’s scientific sessions in Chicago, found that people who limit eating food to less than eight hours per day had a 91 percent higher risk of fatal cardiovascular disease when compared with people who eat across 12 to 16 hours a day.

The increased risk of cardiovascular death was also observed in those living with heart disease or cancer, researchers noted. Those who had existing cardiovascular disease and ate between eight and 10 hours per day also had a 66 percent higher risk of death from heart disease or stroke, the analysis stated.

Intermittent fasting, which involves eating during a six-to-eight-hour window and fasting for the remaining 16 to 18 hours, has increased in popularity over the past 10 years. Studies have suggested the diet can help with weight loss, decrease the risk of diseases like cancer, lower blood pressure and boost energy. 

The analysis, by researchers from Shanghai Jiao Tong University School of Medicine in China, is based on the Centers for Disease Control and Prevention’s data of 20,000 adults across the United States from 2003 to 2018. It has not yet been peer-reviewed or published in an academic journal. However, it is among few to specifically examine the long-term effects of intermittent fasting on the risk of death from cardiovascular disease.

“Restricting daily eating time to a short period, such as 8 hours per day, has gained popularity in recent years as a way to lose weight and improve heart health,” senior study author Victor Wenze Zhong, Ph.D., said in a statement. “However, the long-term health effects of time-restricted eating, including risk of death from any cause or cardiovascular disease, are unknown.”

Zhong said researchers were “surprised” to find those who follow an intermittent fasting diet had a higher risk of cardiovascular death. 

“Even though this type of diet has been popular due to its potential short-term benefits, our research clearly shows that, compared with a typical eating time range of 12-16 hours per day, a shorter eating duration was not associated with living longer,” he wrote. 

Zhong said the findings should encourage individuals to take greater caution when it comes to their diet choices and emphasized these choices should be “aligned” with an individual’s health status. 

The findings do not mean intermittent fasting caused cardiovascular death, and further research should look at the “biological mechanisms” behind the links between the diet and adverse cardiovascular outcomes, he added. He noted the research also depends on individuals’ memories of what they ate.

Zhong told NBC News it is premature to make lay out specific recommendations based on the analysis, writing to the outlet, “Practicing intermittent fasting for a short period such as 3 months may likely lead to benefits on reducing weight and improving cardiometabolic health.” He noted people should take “extreme” caution about intermittent fasting for longer time periods, NBC News reported.