As the incidence of Chronic Non-Communicable diseases (CNCD) increases, preventive approaches become more crucial. In this narrative review, calorie restriction (CR) and fasting effects on human beings were evaluated, comparing their benefits and risks. Special emphasis on insulin resistance was placed, as it mediates metabolic syndrome and therefore has a great impact on the prevalence of CNCD. Calorie restriction is a nutritional intervention of reduced energy intake of about 25 to 30 % without lack of essential nutrients. CR is the most robust nutritional intervention known to increase lifespan and health span, with high evidence and known biochemical mechanisms, such as neuroendocrine system adaptations (figure 1). CR improves cardiometabolic risk parameters, boosts exercise insulin sensitivity response and there may be benefits of implementing moderate CR on healthy young and middle-aged individuals, as shown in the CALERIE 2 study (Kraus et. al). Fasting is a voluntary abstinence or reduction of some or all foods, drinks, or both, for a varying period of time. There is a variety of fasting protocols (figure 2), such as intermittent fasting (IF), that involves fasting for 12h or longer. Some of the studied effects of intermittent fasting in humans include increased insulin sensitivity, decreased levels of leptin, pro-inflammatory cytokines and oxidative stress markers, healthier blood pressure, improved circadian rhythmicity and cognition, increased autophagy and modulation of microbiota. Studies in normal and overweight individuals have shown efficacy of IF on weight loss and improvement of insulin resistance and cardiovascular risk factors. Studies show inconsistent benefits of fasting compared to CR. More studies are required to evaluate biochemical parameters, reinforce evidence, and seek effective and safe nutritional approaches. Nevertheless, the available data suggests CR and fasting as potential approaches to maintain and increase health span.
Share this page on your timeline