It’s not only what you eat, but when you eat. Intermittent fasting, once the darling of Silicon Valley executives, Hollywood actors, and even former British Prime Minister Rishi Sunak, has been celebrated as a shortcut to weight loss and higher energy. But a sweeping new study is casting a long shadow over the trend, finding a 135% higher risk of death from cardiovascular disease among those who restricted eating to fewer than eight hours a day.
The diet, usually structured around 16 hours of fasting and an eight-hour eating window, promised to “hack” the body’s biology—bypassing tedious calorie counting or carb bans by focusing simply on the clock. Advocates sold it as a smart road to better metabolism, cell repair, and even longevity. Yet the latest findings suggest the opposite may be true.
Published in Diabetes & Metabolic Syndrome: Clinical Research & Reviews, the study analyzed the records of nearly 20,000 American adults tracked for more than 15 years. The conclusion: those squeezing meals into under eight hours faced dramatically higher cardiovascular mortality compared to people who spread eating over 12–14 hours.
“The statistical analysis clearly linked shorter eating windows with higher cardiovascular deaths,” explained Dr. Sigal Frishman, chief dietitian at Clalit Health hospitals. The risk cut across every category—age, gender, race, lifestyle—but it loomed largest among smokers, diabetics and patients already living with heart disease.
To be clear, intermittent fasting has shown short-term gains—weight loss, lower blood pressure, and reduced inflammation. But as Professor Victor Wenze Zhong of Shanghai Jiao Tong University, who led the research, cautioned: “These findings challenge the assumption that intermittent fasting is free of risks.” He urged those with chronic conditions to be especially careful before adopting extreme time restrictions.
The advice now is moderation: a daily eating window of 10–12 hours may be safer than the rigid eight-hour limit. More important still, say the researchers, is the quality of food—balanced, protein-rich, plant-heavy meals with fewer processed sugars and fats.
Der. Sigal FrishmanPhoto: Rami ZerengerIn the end, the study doesn’t close the book on intermittent fasting, but it does add a warning label. Extreme versions may trade quick benefits for long-term damage, reminding us that health is rarely about a single rule, but about balance, consistency, and paying attention when the body pushes back.