Intermittent Fasting: The surprising risks of time-restricted eating

In pursuing better health and wellness, many have turned to time-restricted eating, a form of intermittent fasting, hoping to shed pounds and improve heart health. However, recent research unveiled at the American Heart Association’s Epidemiology and Prevention suggests a cautionary note regarding this dietary trend.

Contrary to expectations, a study analyzing data from over 20,000 U.S. adults found that restricting eating to less than 8 hours per day, a popular time-restricted eating plan may heighten the risk of cardiovascular disease mortality compared to more extended eating durations.

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Time-restricted eating, characterized by limiting food intake to specific hours within a day, has gained traction for its potential to enhance cardiometabolic health. A typical regimen involves consuming all meals within a set window, often spanning from 4 to 12 hours, followed by a fasting period.

The widely practiced 16:8 schedule, where individuals eat within an 8-hour timeframe and fast for the remaining 16 hours, has garnered significant attention. Proponents cite previous research indicating improvements in blood pressure, blood glucose levels, and cholesterol profiles among adherents.

However, the long-term consequences of this dietary approach remained uncertain until now. Senior study author Victor Wenze Zhong and colleagues from Shanghai Jiao Tong University School of Medicine extensively investigated the potential health ramifications of an 8-hour time-restricted eating plan. Their study, based on data from the National Health and Nutrition Examination Surveys (NHANES) from 2003 to 2018 and mortality records from the Centers for Disease Control and Prevention, revealed surprising findings.

Among the key discoveries was a startling 91% higher risk of death due to cardiovascular disease among individuals adhering to a sub-8-hour eating window. This elevated risk persisted even among those already grappling with heart disease or cancer. Notably, participants with pre-existing cardiovascular conditions who adhered to an eating duration of less than 10 hours per day also faced a 66% increased risk of death from heart disease or stroke. Despite these concerning findings, time-restricted eating did not exhibit a significant effect on overall mortality risk.

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The study’s results challenge conventional wisdom surrounding the benefits of time-restricted eating and underscore the importance of nuanced dietary recommendations tailored to individual health statuses. While the short-term advantages of such regimens may hold true, particularly in weight management, the potential long-term repercussions demand careful consideration.

Christopher D. Gardner, Ph.D., FAHA, of Stanford University, underscores the need for a comprehensive understanding of dietary patterns beyond mere eating windows. He emphasizes assessing nutrient density and demographic characteristics to discern alternate explanations for the observed outcomes. Moreover, Gardner highlights the need to explore potential confounding factors such as stress and traditional cardiometabolic risk factors to interpret the study’s findings better.

Future research endeavors may delve into the biological mechanisms underlying the association between time-restricted eating and adverse cardiovascular outcomes. While time-restricted eating may offer short-term benefits, particularly in weight management, its long-term implications for cardiovascular health warrant scrutiny.