New research has found that maintaining a healthy body weight may help people to live longer, providing severely overweight people with a further incentive to seek obesity treatment.
In a report published in Science, researchers describe a study which found that reducing insulin signals inside brain cells increased the lifespan of mice.
Mice which ate half the amount of the protein IRS2 - which carries the insulin signal in the brain - lived for 18 per cent longer than normal mice and researchers suggest that reducing insulin by achieving a healthy lifestyle and weight may have the same effect in humans.
Study leader Dr Morris White, a researcher at the Howard Hughes Medical Institute, explained: "Our findings put a mechanism behind what your mother told when you were growing up - eat a good diet and exercise, and it will keep you healthy."
The researcher added that dieting and achieving a lower weight helps to reduce the amount of insulin secretion needed to keep glucose under control when you eat, meaning that the brain is exposed to less insulin.
A spokesman for Diabetes UK told the BBC that insulin could therefore play a role in the ageing process.
"We welcome the fact that this study supports our key message of the importance of leading a healthy lifestyle," he added.