Could Carbohydrate -Concentrated Diets Mimic Calorie Restriction in Slowing the Aging Process?

Although calorie restriction and alternate-day fasting have potential for slowing the aging process while decreasing risk for vascular disease, diabetes, cancer and dementia, a “carbohydrate-concentrated” diet strategy, entailing long daily periods of carbohydrate abstinence, may prove to be a much more practical strategy for achieving these aims. The life extension and healthy aging benefits of calorie restriction appear to be mediated primarily by sustained reductions in plasma levels of insulin, free IGF-I, and glucose, which in turn induce down-regulation of Akt and mTORC1, and up-regulation of Sirt1, AMPK, and the FOXO transcription factors. The health protective consequences of these effects include up-regulation of apoptosis – helping to rid the body of pre-cancerous cells – and autophagy, which aids control of oxidative stress while clearing cells of structurally damaged proteins and membranes. Increased FOXO activity boosts expression of many antioxidant enzymes and aids DNA repair; increased Sirt1 activity has an anti-inflammatory impact. Calorie restriction also promotes central neuroprotection by increasing brain expression of neural growth factors, Sirt1, and heat shock proteins. The benefits evoked by calorie restriction are not crucially dependent on calorie deficit per se, since alternate day fasting has likewise been shown to increase maximal lifespan and promote neuroprotection – even if animals maintain their previous calorie intakes by eating ravenously on the fed days. Hence, repeated prolonged episodes of diminished insulin, free IGFI, and glucose appear sufficient to achieve the aging retardant and health benefits associated with calorie restriction. Modified alternate-day fasting – allowing modest calorie intake during the “fasting” days – has shown clinical utility for ameliorating inflammatory disorders and promoting weight loss, but is probably too rigorous to achieve widespread popularity. Carbohydrate-concentrated (CC) diets – in which most of the day’s carbohydrate intake is segregated to one main meal, and optional accessory low-carb meals are allowed – appear to have considerable utility for weight control, and their prolonged periods of relatively low insulin, free IGF-I, and glucose may evoke to some degree the manifold health and pro-longevity benefits seen in calorically-restricted or alternate-day-fasted rodents. Moreover, adherence to such regimens appears to be quite feasible, as suggested by the widespread popularity of the CC diet program promulgated by Drs. Rachael and Richard Heller as a weight control strategy. CC diets composed of plant foods are likely to have the greatest positive impact on health and longevity, as they should reduce plasma IGF-I levels, while also promoting muscle insulin sensitivity and thereby down-regulating insulin secretion.