The longevity benefits of calorie restriction have been demonstrated across every animal model studied, from yeast to primates. In the roundworm C. elegans, calorie restriction extends lifespan by 40 percent. In rhesus monkeys, a 30 percent calorie restriction produces measurably slower biological ageing and reduced incidence of age-related disease. The challenge is applying these findings to humans, for whom indefinite 30 percent calorie restriction is neither practical nor psychologically sustainable.
The Fasting-Mimicking Diet Research
Valter Longo's group at USC developed a fasting-mimicking diet protocol of 800 to 1,100 calories per day for 5 consecutive days per month, designed to activate the same metabolic pathways as fasting while providing enough nutrition to maintain adequate nutrient status. Three cycles of this protocol produced significant reductions in IGF-1 and insulin, reductions in inflammatory markers, reduction in cardiovascular risk factors, and measurable reductions in biological age as assessed by epigenetic clock analysis.
Autophagy as the Central Mechanism
Autophagy is the cellular housekeeping process that removes damaged proteins, organelles, and cellular debris. It is activated by fasting, calorie restriction, and the reduction of mTOR signalling that occurs when amino acid and glucose availability falls. Autophagy is suppressed by regular high-protein and high-carbohydrate feeding. For adults who cannot fast but want to activate autophagy periodically, a 16 to 18-hour overnight fast several times per week produces partial autophagy activation that is physiologically meaningful.