There has been a general finding that calorie restricted eating is linked to a longer lifespan and less disease.
For example, when Koletsky and Puterman put genetically obese mice on a calorie restrained diet, they found health improvements compared to rats that were not placed on the special diet. The diet rats lived longer, lost body weight and reduced obesity, their hypertriglyceridemia (high levels of a fatty substance in the blood) was nearly gone, and had a drop in blood cholesterol levels. While their bouts of high blood pressure didn’t improve over and above the non-diet rats, they were generally a lot better off.
In trying to figure out how this may work, Froy and colleagues studied the circadian rhythms (body clocks) of rats that were bred to have a low calorie diet. They found that calorically restricted animals, rats which were bred to eat less and live longer, had body clocks and circadian rhythms that differed from normal rats.
Now, University of Washington scientists have uncovered how the process works by studying yeast cells. They found that the lifespan extending effects are partly mediated by reduced signaling through TOR. TOR is an enzyme that is involved in many vital operations in a cell. A reduction in signaling through TOR leads to a reduced protein synthesis rate (called transcription). Using a drug called diazaborine, which has its effects on the TOR pathway, the researchers were able to increase the life of the cells by about 50%.
This is all great news for the rats (and yeast), but what about those of us who lack the tail and whiskers (or at least the tail)? Similar trends are seen in people, but it is hard to do this sort of research on humans. Randomly assigning participants into one of two groups where one of the groups will become unhealthy and potentially die is horrendously unethical. Doing this with rats is arguably no better, but ethics committees are more likely to let it go ahead. For this reason most experimental research has focused on non-human organisms and human research has used either a correlational method or focused on interventions.
If you are interesting in finding out more about calorie restricted diets and longevity, have a look at the above links. There is also a great review of the literature (or full PDF).
A new verison of WordPress (2.5.1; what this blog runs on) was released. Being the responsible blogger that I am (responsible or unable to sit still, either is fine), I immediately upgraded.