Experiments on yeast, worms, and mammals have all revealed that cutting calories extends lifespan, but how is this occurs is largely unknown. Now, two independent studies, one reported in the June 18 Science, from David Sinclair's laboratory at Harvard Medical School, and the other reported in the June 3 Nature, from Leonard Guarente's laboratory at Massachusetts Institute of Technology, have uncovered molecular mechanisms linking aging, diet, and a gene called SIRT1.

"People have been studying calorie restriction for 70 years, yet the mechanism is not known," said Sinclair, adding that this new work has finally started to suggest a primary mechanism.

In the past, calorie restriction was theorized to be a passive mechanism, whereby fewer calories reduced metabolism and the oxidative stresses that come with it. But the discovery that the protein Sir2—of which SIRT1 is the mammalian orthologue—extends lifespan in yeast and worms, suggested a more...