The research team believes that avoiding high calorie foods makes the metabolism perform like that of a younger person.
Professor Paolo SassoneCorsi, who led the University of California Irvine study in the US, said the change takes place because older cells process energy “inefficiently”.
But his laboratory tests on mice at different stages of their life suggested the deterioration can be offset if the subject’s calorie intake is controlled.
Writing in the science journal Cell he said: “This mechanism works great in a young animal, but it basically shuts off in an old mouse.
“In fact caloric restriction works by rejuvenating the biological clock in a most powerful way.”
Prof Sassone-Corsi, director of the university’s Center for Epigenetics and Metabolism, said: “In this context, a good clock meant good ageing.”
His team set out to study how ageing affects the body clock’s control of metabolism by testing liver and tissue samples from two groups of mice at six months and 18 months old.
They found that the animals fed a diet with 30 per cent fewer calories for six months, did not experience the same age-related decline in energy processing.
The California team’s results were supported by a separate study, also reported in Cell, by academics from the Barcelona Institute For Research.
By studying the effects on the stem cells of the animals they too found that a low calorie diet conserved most of the rhythmic functions of youth.
Professor Salvador Aznar Benitah, who co-led the Spanish study, said: “The low calorie diet greatly contributes to preventing the effects of physiological ageing.
“Eating less appears to prevent tissue ageing and, therefore, prevent stem cells from reprogramming their circadian activities.”