A recent article reported on the evidence of calorie restriction's effectiveness in lengthening the life span of humans. Researchers searched the National Library of Medicine’s database of published research (PubMed) for studies published from 1966 to 2006 that pertained to calorie restriction, aging, longevity, obesity, and other research topics. They next assessed studies they found for quality and methodology.
While they found no evidence on whether calories restriction extends maximum life span, they did find evidence that calorie restriction in adult men and women causes some of the metabolic changes that have been observed in the laboratory cases of monkeys and rats. Namely, calorie restriction in humans decreases metabolic, hormonal and inflammatory risk factors for diabetes, cardiovascular disease and possibly cancer. However, excessive calorie restriction or calorie restriction without proper nutrition has negative effects on overall health.
Researchers could not determine an optimal amount of calories that should be ingested to reduce risk factors. The benefits of calorie restriction may not apply to individuals who already have minimal amounts of body fat (and calorie restriction may even be harmful in these individuals).
Source:
Luigi Fontana, MD, PhD; Samuel Klein, MD. Aging, Adiposity, and Calorie Restriction. JAMA. 2007;297:986-994.
