The data noted here is not news to anyone who has followed calorie restriction research. It is well understood that the practice of calorie restriction is beneficial to long term health, reducing the impact of aging over time. It extends life by up to 40% in mice, but is nowhere near as effective as that in longer-lived mammals, such as our own species, even given similar short-term effects on metabolism. That said, it is interesting to note that enough robust studies of calorie restriction in humans have taken place over the past few decades to justify review papers on the topic.
Uncertainty remains about the risk/benefit balance of calorie restriction (CR) and its transferability to the current medical practice. Although during the last years different reviews and systematic reviews were published related effect of some type of CR on health, there are still no systematic reviews quantitatively summarizing the potential association between CR and multiple dimensions of health status. In fact, different systematic reviews have explored the association between CR and asthma, hypercholesterolemia, cardiovascular health, or bone health. Some systematic reviews have examined the general effects of diet or intermittent energy restriction on health, while others took in consideration specific populations such as intensive care units patients, athletes, or animal models. Hence, the aim of this study was to assess the effects of CR on dimensions of the WHO health concept, with a systematic review and meta-analyses of randomized controlled trials performed on this topic.
A total of 29 articles were retrieved including data from eight randomized controlled trials. All included trials were at low risk for performance bias related to objective outcomes. Collectively, articles included 704 subjects. Among the 334 subjects subjected to CR, the compliance with the intervention appeared generally high. Meta-analyses proved benefit of CR on reduction of body weight, BMI, fat mass, total cholesterol, while a minor impact was shown for LDL, fasting glucose, and insulin levels. No effect emerged for HDL and blood pressure after CR. Data were insufficient for other hormone variables in relation to meta-analysis of CR effects. Our conclusion is that CR is a nutritional pattern linked to improved cardiometabolic status. However, evidence is limited on the multidimensional aspects of health and requires more studies of high quality to identify the precise impact of CR on health status and longevity.