Your article on the search for a cure for ageing described experiments that showed semi-starved rats and mice live up to 50 per cent longer (22 September, p 28). But if these experiments were performed on captive animals denied access to exercise facilities or sufficient space to get a normal amount of exercise, there is a simple explanation for the results. They would only apply to humans if people were similarly incarcerated.
Many years ago Jean Mayer demonstrated, in both rodents and humans, that the energy consumed when food was freely available was linearly proportional to the amount of exercise performed by the subjects, if, and only if, the amount of exercise exceeded a certain minimal amount. Below this amount, the less exercise the rodents or humans took, the more they ate.
Thus, one would expect incarcerated rodents (or humans) to consume calories in inverse proportion to their needs, ...
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