Less fat tissue is unambiguously good for you over the long term, and one side effect of calorie restriction is the loss of excess fat tissue - but that is only a side effect. More interesting stuff is going on at the level of cells and their mechanisms: "Caloric restriction (CR) slows the aging process and extends longevity, but the exact underlying mechanisms remain debatable. It has recently been suggested that the beneficial action of CR may be mediated in part by adipose tissue remodeling. Mammals have two types of adipose tissue: white adipose tissue (WAT) and brown adipose tissue (BAT). In this study, proteome analysis [was] performed on both WAT and BAT from nine month old male rats fed ad libitum or subjected to CR for six months. Our findings suggest that CR activates mitochondrial energy metabolism and fatty acid biosynthesis in WAT. It is likely that in CR animals WAT functions as an energy transducer from glucose to energy-dense lipid. In contrast, in BAT CR either had no effect on, or down-regulated, the mitochondrial electron transport chain, but enhanced fatty acid biosynthesis. This suggests that in CR animals BAT may change its function from an energy consuming system to an energy reservoir system. Based on our findings, we conclude that WAT and BAT cooperate to use energy effectively via a differential response of mitochondrial function to CR." It is worth noting that there are other signs that the biochemistry of fat tissue, and its effects on health, can be dramatically altered - see the research on fat in GHRKO mice, for example.