Results of a study by researchers at the University of Texas Barshop Institute for Longevity and Aging Studies and the University of Colorado suggest that calorie restriction does not always promote longevity. James Nelson, professor of physiology at Barshop, and colleagues studied the effect of calorie restriction on fat and weight loss in 41 strains of mice. The researchers then used their data to examine the relationship between fat loss and lifespan modulation. Results showed that life extension correlated inversely with fat reduction at midlife, thus meaning that mice that maintained their fat lived longer, whilst those that lost fat died earlier. “Indeed, the greater the fat loss, the greater the likelihood the mice would have a negative response to dietary restriction, i.e., shortened life,” said Professor Nelson. “This is contrary to the widely held view that loss of fat is important for the life-extending effect of dietary restriction,” he added. Although the researchers warn that their findings cannot be directly applied to people at this stage, they recommend that people adopt a moderate approach to weight loss, by not losing all their body fat but not keeping excess fat either. They conclude: “If these results translate to humans, they would suggest that individuals who have difficulty losing weight may benefit from the positive effects of dietary restriction more than those who lose weight easily.”