The Effect of Caloric Intake on the Aging Process

Clinically speaking, aging is complicated. Currently, more than 300 theories explain various processes involved in aging. In a recent article published ahead of print in Current Opinions in Clinical Nutrition Metabolic Care, the authors reviewed one well-researched trend related to aging: reduced caloric intake and longevity in animal models.

The authors highlighted one established point: excessive caloric intake accelerates aging in mammals. Conversely, restricting caloric intake (if it doesn't reach the point of malnutrition) has been shown to lengthen lifespans in animal models varying from worms to primates. In primates (the animal nearest to humans in terms of evolution) 20 years of caloric restriction has been linked to lower rates of cancer, brain atrophy, cardiovascular disease, and diabetes.

The authors list multiple mechanisms by which caloric restriction lengthens lifespan, including improved resistance to oxidative stress, changes in mitochondrial dynamics, reduced cell aging, telomere attrition, and many others.

The authors also note that the average lifespan of a species is strongly dependent upon body size, with lifespan increasing 16% as body size doubles. Therefore the authors suggests that researchers direct their attention to animals that have lifespans far beyond what is predicted. For example, as compared to similarly-sized mice, naked mole rats live 8 times longer. They are an exceptional animal model for longevity studies.

While reducing caloric intake is steadily associated with longer lifespans in animals, most humans find long-term caloric restriction challenging at best, impossible at worst. Early evidence shows that calorie restriction--a decrease of 25% of ad libitum intake--is feasible and improves weight and cardiometabolic risk factors.

Some drugs appear to be caloric restriction mimetics, including selective mTOR inhibitors and SIRT1 agonist. In the future, use of these drugs may prolong healthy life in humans. Studies of extremely long-lived small-size animals, such as the NMR, may provide important clues for treatment of human ageing.”