The relationship between diet and longevity encompasses diverse research studies involving both humans and animals, requiring an analysis of complex mechanisms underlying the potential relationship between various dietary practices, health, and longevity.

As of 2021, there is no clinical evidence that any dietary practice reverses the biological effects of aging.^[1]

The concept of fasting and longevity involves abstaining from food to decrease the incidence of diseases and increase lifespan. The use of fasting dates to the 5th century BC, as attributed to Greek physician Hippocrates who suggested that people with certain illnesses should abstain from food or drink as therapy.^[2]

Although health can be influenced by diet, including the type of foods consumed, the amount of calories ingested, and the duration and frequency of fasting periods,^[3] there is no good clinical evidence that fasting promotes longevity in humans, as of 2021.^[1][4][5]

Calorie restriction is a widely researched intervention to assess effects on aging, defined as a sustained reduction in dietary energy intake compared to the energy required for weight maintenance.^[1][4] To ensure metabolic homeostasis, the diet during calorie restriction must provide sufficient energy, micronutrients, and fiber.^[4] Some studies on rhesus monkeys showed that restricting calorie intake resulted in lifespan extension, while other animals studies did not detect a significant change.^[1][6]

According to preliminary research in humans, there is little evidence that calorie restriction affects lifespan.^[1][4]