Scientists have discovered that reducing calories by as much as 30 per cent – just above malnutrition levels – could dramatically lower risks of developing cronic heart disease (CHD) or cancer by half and increase lifetimes by nearly a third.

This extreme low calorie diet could add as much as 25 years to the average life in Britain with the vast majority of people living to at least a 100 years old.

The life expectancy comes at a price though – the suggestion is that each person would have to have a specially tailored diet, probably made from milk protein and corn oil. Not only that but we would also have to supplement this low calorie diet with special vitamin and mineral tablets in order to make sure that what the diet lacked in essential nutrients was still ingested in some way.

The researchers based at the University of Wisconsin, a study which appeared in the journal Science, began their study in 1989 to see if a restricted diet – already shown to work in mice – would have an effect on the lifespan of more sophisticated mammals.

The research team have been following the lives of macaques, which have a normal lifespan of 27 years. All subjects were enrolled as adults with the oldest monkey being 14 years old.

For the first period of study (3 - 6 months, the animals were observed to see how much food they would naturally eat – then half of the animals were put on the extreme diets that cut their calorie count by 30 per cent while the others carried on eating their normal diet.

During the course of the 20-year study, 50% animals permitted to eat freely have survived, while 80% of the monkeys given the same diet, but with 30% fewer calories, are still alive. The oldest surviving imacaque s now 29 years old.

However, not only did the monkeys live longer but also the recorded levels of heart disease and cancer was found to be lower in the animals that eat the restricted diet - something which would have a dramatic effect on the life expectancy of humans as well as the test case animals used in the study.

Chronic heart disease (CHD) and diseases such as diabetes have been to be linked directly to weight gain and obesity. By  dramatically cutting down on calories, via a restrictive diet, the amount of human deaths due to CHD and other illnesses, there would be a decrease in deaths - hence we would live longer in the process.