London - It is a drastic diet which removes the need for "calorie counting" by simply banning all food every other day.
But "alternate day fasting" could help followers cut their calorie intake by more than a third and lose more than half a stone in a month, it is claimed.
Scientists studied what happens when someone alternates "fast days", where food is banned, with "feast days" when they eat what they want.
The diet is based on our caveman past, when we feasted after killing a large animal, but often faced food shortages which left us hungry.
The researchers, led by the Medical University of Graz in Austria, found 30 people on this diet lost around 14.5 percent of their body fat, saw their blood pressure and "bad" cholesterol drop, and reduced their risk of a heart attack or stroke over the next decade.
In blood tests they had lower levels of an important hormone and amino acid, which may help them to live to an older age.
The findings follow growing evidence that fasting every so often could help people to live longer, which has been seen to be the case in rhesus monkeys and mice.
Study co-author Professor Thomas Pieber said: "Why exactly calorie restriction and fasting induce so many beneficial effects is not fully clear yet. The elegant thing about strict alternate day fasting is that it doesn’t require participants to count their meals and calories – they just don’t eat anything for one day."
The study, published in the journal Cell Metabolism, recruited 60 people aged 35 to 65, putting half on the fasting diet and letting the rest eat as normal for a month.
Those on the diet fasted for 36 hours at a time, being banned from eating all solid and liquid foods, and drank only water, flavoured water, coffee, green tea or unsweetened black tea. This was followed by 12 hours of eating what they liked, during which they made up for only some of the calories they missed while fasting.
Researchers found the dieters cut their calories by 37 percent in total, losing almost 7.7lb (3.5kg) after four weeks. Their risk of cardiovascular disease, such as a heart attack or stroke, over the next decade was reduced compared to the 30 people eating normally.
The benefits were similar to those seen in dieters who count calories, but the researchers say fasting is simpler, meaning people are less likely to fall off the wagon.
Concerns have been reported that fasting in such an extreme way could cause health problems, but those on the diet did not have significantly lower bone density or changes to their immune system.
Another 30 study participants were already performing alternate day fasting for six months, which was reported to be safe.
However the study authors do not recommend the diet for everyone, with co-author Frank Madeo stating: "We feel that it is a good regime for some months for obese people to cut weight, or it might even be a useful clinical intervention in diseases driven by inflammation. However further research is needed."