Restricting calorie intake in middle age may lengthen life, researchers have found.
Cutting down is recommended
It had previously been suggested keeping your calorie intake to a minimum had to begin earlier to have an impact.
Research on mice, published in the Proceedings of the National Academy of Sciences, showed reducing calories later on life still prolonged lifespan.
Dietary experts said more evidence was needed into the effect on humans.
Proponents of the theory of
Caloric restriction (CR) claim that a diet which keeps the number of calories to a bare minimum while ensuring the required amount of nutrition is taken on board lengthens life.
Research on dogs and rodents has backed the suggestion but the jury is still out on the effect on humans.
CR in late middle-aged mice reaped benefits almost immediately, the researchers at the University of California found.
Lifespan was extended by almost six months and deaths due to cancer were delayed, perhaps by decreasing the rate of tumour growth.
The researchers said the effect on liver gene expression was similar to that in mice who began CR at a younger age.
"CR begun relatively late in the lifespan of mice was as effective as CR begun early in life at decelerating mortality rate, extending remaining lifespan, and delaying the onset or progression of cancer as a cause of death," they concluded.
They suggested drug therapies that induce the same patterns of gene activity could produce the same age-retarding effects.
A spokeswoman for the British Dietetic Association said: "It is certainly the case that animal studies have found that calorie restriction may prolong lifespan. However, it is not clear whether this is also the case for humans. More research is needed in this area."
She added, however, that as Britain was "in the grips of an obesity epidemic" cutting calorie intake at any age and increasing exercise would help those who are overweight and obese to reduce their health risk and live longer.
"From this perspective, for many of us, cutting down on energy intakes could be beneficial to our health," the spokeswoman said.