8 Hour Time Restricted Eating Linked To Increased Risk Of CVD Death

Time-restricted eating involves only eating within a specific amount of hours a day which can range from a 4 to 12-hour eating window. One of the more popular eating schedules is the 16:8 schedule where people eat all of their food within an 8-hour window and fast for the remaining 16 hours in the day. 

"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," said senior study author Victor Wenze Zhong, Ph.D., a professor and chair of the department of epidemiology and biostatistics at the Shanghai Jiao Tong University School of Medicine in Shanghai, China. "However, the long-term health effects of time-restricted eating, including risk of death from any cause or cardiovascular disease, are unknown."

This study investigated the potential long-term health effects of following the 16:8 eating plan by reviewing data from the 2003-2018 National Health and Nutrition Examination Surveys (NHANES) in comparison to data from those who died in America during the same time frame from the CDC’s National Death Index database. The study involved around 20,000 adults with an average age of 49 years old who were followed for a median length of 8 years and maximum of 17 years. 

The analysis revealed that those who followed the pattern of eating all their food across less than 8 hours a day had a 91% higher risk of death due to cardiovascular diseases, the increased risk was also seen in those living with cancer and heart disease. Among those with existing CVD, an eating duration between 8-10 hours a day was associated with a 66% higher risk of death from stroke or heart disease. 

Time-restricted eating was found not to reduce the overall risk of death from any cause compared to a standard schedule of eating across 12-16 hours a day, while an eating duration of more than 16 hours a day was associated with a lower risk of cancer mortality among those living with cancer. 

"We were surprised to find that people who followed an 8-hour, time-restricted eating schedule were more likely to die from cardiovascular disease. 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," Zhong said.

"It's crucial for patients, particularly those with existing heart conditions or cancer, to be aware of the association between an 8-hour eating window and increased risk of cardiovascular death. Our study's findings encourage a more cautious, personalized approach to dietary recommendations, ensuring that they are aligned with an individual's health status and the latest scientific evidence," he continued. "Although the study identified an association between an 8-hour eating window and cardiovascular death, this does not mean that time-restricted eating caused cardiovascular death." 

"Overall, this study suggests that time-restricted eating may have short-term benefits but long-term adverse effects. When the study is presented in its entirety, it will be interesting and helpful to learn more of the details of the analysis," said Christopher D. Gardner, Ph.D., FAHA, the Rehnborg Farquhar Professor of Medicine at Stanford University in Stanford, California, and chair of the writing committee for the Association's 2023 scientific statement, Popular Dietary Patterns: Alignment with American Heart Association 2021 Dietary Guidance.

"One of those details involves the nutrient quality of the diets typical of the different subsets of participants. Without this information, it cannot be determined if nutrient density might be an alternate explanation to the findings that currently focus on the window of time for eating. Second, it needs to be emphasized that categorization into the different windows of time-restricted eating was determined on the basis of just two days of dietary intake," he said.

"It will also be critical to see a comparison of demographics and baseline characteristics across the groups that were classified into the different time-restricted eating windows -- for example, was the group with the shortest time-restricted eating window unique compared to people who followed other eating schedules, in terms of weight, stress, traditional cardiometabolic risk factors or other factors associated with adverse cardiovascular outcomes? This additional information will help to better understand the potential independent contribution of the short time-restricted eating pattern reported in this interesting and provocative abstract."