It should be noted that there was a small reduction in mortality (24% in the control group versus 20% in the CR group in young onset CR initiation). Their results contrasted sharply with life prolonging affects seen in rhesus monkeys at the Wisconsin National Primate Research Center trial, where 37% of monkeys in the control group died compared to 13% in the CR (caloric restriction) group at the time of publication a few years ago..
Click on the link below to see the study.
One factor that is mentioned in this NIA study to try to explain why their results contrasted quite significantly from the primate study done at the Wisconsin Primate Research Center is that “diet composition may strongly affect the life prolonging effect of calorie restriction in a long-lived nonhuman primate”. I would have to see exactly what they were feeding the monkeys at each of the centers to ascertain a difference, however, I do know that they were feeding the monkeys approximately a 60% carbohydrate diet at NIA. That may be way too much to ascertain a clear benefit of CR (caloric restriction) to life extension. Additionally, triglycerides increased throughout life in both the control and calorie restricted groups. This indicates that burning energy from fat was quite limited in both groups. I believe that what I have said for two decades is very true; that health and longevity will be determined by the proportion of fat verses sugar one burns over a life time. The monkeys in this study were likely still being forced to burn sugar and minimal fat as their primary fuel, secondary to the high carbohydrate diet they were still being fed.
I have long maintained that it is not calorie restriction but carbohydrate and protein restriction that mediates effects of longevity, and that typical calorie restriction reduces calories from both proteins and carbohydrates to a very limited extent. I feel one can go much further in showing benefits of CR (caloric restriction) with a very low carbohydrate, high-fat, and low to moderate protein diet.
It is now becoming known that the health and life prolonging effects of calorie restriction are not due primarily to calorie restriction per se but are mediated through lowering of metabolic pathway signaling, namely insulin, mTOR, and likely leptin in “higher” animals that use fat as a primary fuel. Therefore the macronutrient content of the diet is extremely important, however this was not well known to the experimenters when these rhesus monkey experiments were initiated over two decades ago.
Check out my comments on the new Harvard Study published late in June, 2012, where the Journal of the American Medical Association raised a challenge by publishing a Harvard study involving three different diets, and how each diet affects the likelihood of gaining weight.