After over-indulging in hot cross buns and chocolate eggs over Easter, many of us will be embarking on a strict diet to lose weight before summer really hits.

And with so many different food fads to follow, from Paleo and Dukan to Atkins, finding the most effective one can be a minefield.

But, according to a new American study of the 11 most popular eating plans, only two are considered truly effective in the long run: Weight Watchers, and Jenny Craig.

The report, which studied 45 trials over a 12-year period by the Johns Hopkins University School of Medicine, cited both as having long-term benefits.

Others, including the Atkins diet, Slim-Fast and the Biggest Loser Club, were said to have possible evidence of immediate weight loss but no definitive proof that they help dieters keep the weight off for a long time.

Jeanne Clark, Professor of Medicine, said: “We want people to experience the health benefits of weight loss - such as lower blood pressure, cholesterol and blood sugar - and lower risk of developing diseases like diabetes.”

The findings, published in the Annals of Internal Medicine, called for more rigorous testing.

“Doctors need to know which programmes have rigorous trials showing they work, but they haven’t had much evidence to rely on,” the authors added.

“Our review should give clinicians a better idea of what programmes they might consider for their patients.”