Slimmers lose twice as much weight on the 5:2 diet as those who try “Cavemen” style paleo regimes, research suggests.
A study comparing popular modern diets found that fasting regimes - which typically cut calorie intake to around quarter of regular consumption, two days a week - were the most successful.
Over the course of a year, dieters shed an average of nine pounds.
Those on the “paleo '' diet - which focuses on heavy consumption of meat - dropped just four pounds. Meanwhile, those on the Mediterranean diet lost six pounds on average, scientists found.
The findings, published in the American Journal of Clinical Nutrition, come from Canadian research on 250 dieters.
Scientists found the Med diet - which encourages consumption of fruit, vegetables, whole-grain breads and cereals, legumes, nuts, seeds and olive oil - was the healthiest regime.
Those on the diet, which severely restricts red meat and limits consumption of fish, chicken, eggs and dairy - saw significant improvements in their blood pressure and glucose levels.
Such changes cut the risk of heart disease and diabetes.
Dieters were also more likely to stay on the diet, with 57 per cent still on it after 12 months.
Almost as many of those who tried regimes of intermittent fasting, like the 5: 2 diet, stuck with it.
In total, 54 percent of those who chose such regimes were on them a year later.
Meanwhile just 35 per cent who opted for the paleo “caveman” eating plan stuck with it.
This diet had an emphasis on animal proteins, nuts, coconut products and extra-virgin olive oil.
While "original" Paleo diets exclude all legumes, dairy and grains, the version in this study allowed some dairy as well as up to one serving daily of legumes and grain-based food.
Co-lead author Dr Michelle Jospe, from the the University of Otago in Canada said the Med diet was the regime that slimmers were most likely to stay on.
She said: "Our participants could follow the diet's guidelines more closely than the fasting and paleo diets and were more likely to stay with it after the year, as our retention rates showed."
Co-lead author Dr Melyssa Roy said: "In the real world, the one right way to lose weight and eat right is that you can find what suits you the best, and whatever diet is the best is the one you stick to.
"If you choose something that suits you, and is basically a selection of healthy foods, and perhaps eating a bit less often, you can actually get real-world benefits and just live a normal life, and lose weight and see improvements in your health."