Intermittent Fasting-Impacts on Metabolic Health and Longevity

Intermittent fasting (IF) -an umbrella term for eating patterns that cycle between periods of fasting and eating (including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet) -has gained substantial attention as an intervention for weight management, metabolic health, and possibly longevity. Evidence from randomized controlled trials (RCTs), meta-analyses, and animal studies indicates that IF typically reduces body weight and fat mass and can improve insulin sensitivity, fasting insulin, and some lipid markers, though results vary by fasting regimen, baseline weight, and adherence. Mechanistic research implicates metabolic switching, enhanced autophagy(definition), modulation of insulin/IGF-1 signalling, AMPK/SIRT1 activation, and circadian alignment as mediators of benefits. Animal models consistently show lifespan extension under certain forms of dietary restriction or TRF, but translation to humans remains uncertain; human longevity data are sparse and primarily indirect. IF is generally safe for many adults when carefully implemented, but certain populations (pregnant women, children, individuals with eating disorders, some with type 1 diabetes) should avoid it or use medical supervision. Key research gaps include long-term human trials assessing durability and direct effects on hard outcomes (cardiovascular events, incident diabetes, mortality), personalized responses based on genetics and microbiome, and optimal fasting prescriptions for different clinical goals.