Dietary restriction (DR) and fasting protocols, including the Fasting-Mimicking Diet (FMD), extend healthspan and lifespan by activating cellular stress response pathways and autophagy, while inhibiting pro-aging growth pathways like mTOR and the insulin/IGF-1 signaling axis. Periodic FMD cycles can reduce biological age, decrease systemic inflammation, and improve metabolic markers such as blood glucose and insulin levels, all while minimizing the negative consequences of chronic malnutrition.

The Mediterranean Diet (MedDiet) is widely considered the gold standard for long-term longevity and cardiovascular prevention. Rich in vegetables, legumes, whole grains, and healthy monounsaturated fats (like olive oil), it exerts potent anti-inflammatory and antioxidant effects. High adherence to the MedDiet is consistently linked to longer telomere length (a cellular biomarker of aging), reduced risk of cardiovascular disease, and slower cognitive decline.

The Ketogenic Diet (KD) is a high-fat, very low-carbohydrate regimen that induces nutritional ketosis, shifting the body's primary fuel from glucose to ketone bodies. It is highly effective for short-term weight loss, improving insulin sensitivity, and rapid glycemic control. However, it poses long-term sustainability challenges and potential health risks, such as elevated LDL cholesterol in some individuals ("hyper-responders") and complications for those with pre-existing kidney disease.

Plant-Based and Vegan Diets are also strongly associated with longevity and offer significant environmental benefits, including vastly lower carbon footprints than meat-heavy keto diets. Recent studies demonstrate that even short-term vegan diets can significantly reduce epigenetic age metrics and markers of biological aging across multiple organ systems compared to omnivorous diets.

Finally, emerging geroscience research indicates that macronutrient balance—particularly a low-protein, high-carbohydrate (LPHC) ratio—may dictate lifespan more than total caloric intake. LPHC diets have been shown to optimize cardiometabolic health and longevity in animal models by suppressing mTOR activation and reducing circulating branched-chain amino acids. Ultimately, research suggests the "optimal" longevity diet is not static but evolves with age, shifting from higher protein in youth (for growth) to lower protein and higher complex carbohydrates in middle age to prevent chronic disease.