Starving yourself on alternate days can make you live longer, according to scientists.

A group of Americans have said that fasting on and off can boost brain power and help to lose weight at the same time.

The National Institutes for Aging said their research was based on giving animals the bare minimum of calories required to keep them alive and results showed they lived up to twice as long.

The diet has since been tested on humans and appears to protect the heart, circulatory system and brain against age-related diseases like Alzheimer's.

'Dietery energy restriction extends lifespan and protects the brain and cardiovascular system against age-related disease,' said Mark Mattson, head of the laboratory of neurosciences at the NIA and professor of neuroscience at John Hopkins University in Baltimore.