Study Links Intermittent Fasting to 91% Increase In Cardiovascular Mortality


Intermittent fasting has been linked to a 91 percent increase in cardiovascular disease.

New research presented at the American Heart Association’s Epidemiology and Prevention Lifestyle and Cardiometabolic Health Scientific Sessions in Chicago, unveiled startling findings about the popular diet trend of time-restricted eating, often called intermittent fasting. Conducted over 15 years and involving more than 20,000 U.S. adults, the study revealed a significant link between an 8-hour time-restricted eating plan and a 91 percent higher risk of death from cardiovascular disease. This analysis, stemming from data collected via the National Health and Nutrition Examination Surveys (NHANES) between 2003 and 2018, challenges the previously perceived benefits of this diet method, emphasizing the need for a more nuanced approach to dietary recommendations.

Victor Wenze Zhong, Ph.D., the study’s senior author, expressed his concerns about intermittent fasting. “We were surprised to find that people who followed an 8-hour, time-restricted eating schedule were more likely to die from cardiovascular disease,” he said in a statement, stressing the importance of individualized dietary guidance, especially for those with existing heart conditions or cancer, to mitigate the increased risk of cardiovascular death associated with such dietary patterns. Zhong’s comments highlight a critical reassessment of time-restricted eating’s long-term effects on health.

Woman eats kale salad.
Photo courtesy Nutriciously

The study compared the health outcomes of individuals adhering to an 8-hour eating window with those of participants who consumed food across a more traditional 12-16 hour timeframe. Notably, it found no evidence to suggest that restricting eating times to less than 8 hours per day extends life expectancy. Furthermore, individuals with existing cardiovascular diseases eating within an 8 to 10-hour window faced a 66 percent heightened risk of mortality from heart disease or stroke. Interestingly, a longer eating duration of more than 16 hours per day was linked to a reduced risk of cancer mortality among cancer patients.

These revelations call into question the long-term safety of time-restricted eating, a diet strategy that limits daily food intake to specific hours to promote weight loss and enhance cardiometabolic health. Although short-term benefits such as improved blood pressure, glucose, and cholesterol levels have been documented, the potential for adverse cardiovascular outcomes necessitates further investigation.

Christopher D. Gardner, Ph.D., reflected on the study’s implications, emphasizing the need for additional research to unravel the biological mechanisms behind the observed associations and to explore the impact of nutrient density on the findings.

“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.

A cheeseburger in hand.
Photo courtesy Tristan Gassert

“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.”

Gardner’s call for a deeper analysis of demographic and baseline characteristics across different time-restricted eating windows underscores the complexity of dietary impacts on health. As this research unfolds, it serves as a poignant reminder of the intricate relationship between diet patterns and health outcomes. While time-restricted eating may offer certain benefits, this study urges caution and a personalized approach to dietary planning, particularly for those with pre-existing health conditions.

“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,” Zhong said. “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, noting that 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.”

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