The effects of calorie restriction have now been studied in two non-human primates, the macaque Macaca mulatta and the mouse lemur Microcebus murinus. The study on lemurs and one of the two studies on macaques have reported a lifespan increase. In this review, I argue that these results are better explained by a lifespan decrease in the control group because of a bad diet and/or overfeeding, rather than by a real lifespan increase in calorie-restricted animals. If these results can be readily translated to humans, it would mean that no beneficial effect of calorie restriction on lifespan can be expected in normal-weight or lean people, but that overweight and/or obese people could benefit to some extent from a decrease in excessive food intake.