Fewer Calories Does Not Mean a Longer Life?
For a quarter of a century a group of rhesus monkeys were half-starved to see if lean and hungry would mean a longer life. The males in the group were so underfed that they were the body equivalent of a 6-foot human who weighed in at between 120 to 133 pounds.
The hypothesis this experiment was testing was that if the monkeys would live longer and, healthier lives because of the lower lifetime calorie intake, then maybe we humans, their fellow evolutionary primates, could too. Some scientists, in the mistaken belief that the hypothesis would prove true, have been severely restricting their own calorie counts.
The experiment began way back in the ‘80s and the results have been eagerly awaited. Unfortunately the jury remains out on the efficacy of a restricted diet. The underfed monkeys’ life expectancy was no different than the those on a regular diet. The only monkeys that lived longer were those older ones that were put on a diet late in life. The actual reasons for death were no different between the two groups of monkeys either.
Low-Calorie Diet Health Benefits?
Some unusual differences were found with monkeys that were older and who had been put on a low-calorie diet in their later years. Males rather than females had significantly lower levels of cholesterol and blood sugar. All monkeys who were on the late life, low-calorie diet, had low triglyceride levels. These are fat molecules that have been connected with higher probabilities of heart disease. Despite these differences the life expectancy of the underfed monkeys was no longer than that of the well fed ones.
The Caloric Restriction Hypothesis
Like all hypotheses it has some foundation in rationality. Rafael de Cabo, the lead researcher on the monkey starvation plan is said to be surprised and disappointed that the hypothesis is unproven. His expectations were understandable given an earlier study, done at the University of Wisconsin and published in ‘09. This study did a have outcomes that supported the hypothesis that fewer lifetime calories meant a longer life. Their monkeys lived longer!
Or so it seemed, the results of the earlier study are under a cloud however. Since the researchers there, did not include deaths among the study population that they said were ‘unrelated to age’. When these early dead monkeys were counted the caloric restriction leads to longer life hypothesis, was not proven.
Less Calories Are Disappointing?
It seems we have a number of scientists in this area, working hard and being disappointed when they don’t get the results they want. An objective party to it all are the Barshop Institute for Longevity and Aging Studies (Texas university) who say, “this shows the importance of replication in science”. The original Wisconsin study, “was not nearly as conclusive as it was made out to be”.
[box type="important"]The de Cabo study will continue until the youngest rhesus monkey reaches the grand old age of 22 and the researchers still hold out the hope of some benefits. While longevity cannot be correlated with fewer calories there may be a lengthening of the maximum life span for the animals.[/box]