A groundbreaking 2025 study involving over 19,000 adults spanning nearly two decades reveals that intermittent fasting, particularly the popular 16:8 method of consuming all meals within eight hours, is linked to a 135% increased risk of death from cardiovascular diseases compared to eating over longer periods of 12 to 14 hours.
While intermittent fasting has been praised for weight loss and metabolic benefits, experts and health officials are urging caution given the potential long-term heart health risks. Vulnerable groups such as smokers, diabetics, and those with pre-existing heart conditions may face particularly heightened danger. The study calls for personalised medical advice and further research into safe fasting practices.
Long-Term Risks Unveiled in Extensive Research
Researchers utilised data from the US National Health and Nutrition Examination Survey (NHANES) collected between 2003 and 2018, monitoring participants for a median follow-up period of eight years. The participants who adhered to eating windows shorter than eight hours daily were found to have a 135% greater chance of cardiovascular death compared to those who consumed food over a 12 to 14-hour window.
This association remained robust across various demographic factors including age, sex, ethnicity, and lifestyle habits. Smokers, individuals with diabetes, and those suffering from existing cardiovascular diseases demonstrated a disproportionately increased risk.
Professor Victor Wenze Zhong, lead author and epidemiologist at Shanghai Jiao Tong University School of Medicine, stressed the study’s significance, stating, “Short-term studies often report benefits of intermittent fasting, but our findings suggest a more complex long-term impact, especially regarding heart health.
This signals the need for personalised dietary recommendations rather than generalised fasting protocols.” The study, published in Diabetes & Metabolic Syndrome: Clinical Research and Reviews, cautions that while these observational results highlight associations, they do not establish causation.
Biological and Behavioural Complexities Behind Fasting Risks
The increased heart risks linked to intermittent fasting may result from several behavioural and biological mechanisms. Researchers have noted that prolonged fasting can lead to lean muscle loss and circadian rhythm disruptions, undermining cardiovascular health.
Another critical factor is “reward-based eating,” where individuals may overconsume calorie-dense, less nutritious foods during feeding windows, potentially increasing intake of animal proteins and unhealthy fats associated with heart disease. Elevated levels of trimethylamine-N-oxide (TMAO), a metabolite linked to cardiovascular risks, have also been observed in some fasting regimens consuming higher amounts of animal products.
Endocrinologist Dr Anoop Misra, chair of the Fortis-C-DOC Centre for Diabetes and Metabolic Diseases, highlighted intermittent fasting’s metabolic benefits such as improved insulin sensitivity, reduced blood pressure, and anti-inflammatory effects.
However, he warned about nutrient deficiencies, elevated cholesterol, and risks like hypoglycaemia in diabetics practicing unsupervised fasting. “Individuals, especially those with chronic illnesses or older adults, should approach intermittent fasting cautiously and under medical supervision,” he advised.
Expert Guidance and Health Officials’ Recommendations
Health professionals emphasize the importance of moderation and personalised advice when considering intermittent fasting. Dr. Prashant Pawar, a renowned cardiologist, remarked, “Intermittent fasting is not universally suitable.
For some, especially with existing cardiovascular risks, it could be harmful. Medical consultation is vital before starting any such fasting regimen.” Experts urge monitoring nutrient intake, avoiding extreme fasting durations, and ensuring balanced diets rich in plant-based foods for heart health.
The Logical Indian’s Perspective
While intermittent fasting has gained immense popularity as a wellness approach, evolving research indicates the necessity for an evidence-based, personalised approach emphasizing safety and holistic well-being. The Logical Indian advocates for open, respectful discourse rooted in empathy, kindness, and scientific rigor.
Our community thrives when health choices factor in individual differences and when dialogue promotes understanding rather than quick-fix trends.
