From SlimFast to Weight Watchers, there's no shortage of diet plans available - but do any of them actually aid healthy weight loss?
In a bid to tackle the worldwide obesity epidemic, a new study examined popular diets to determine which were the most likely to help a dieter lose excess weight.
The researchers, from Johns Hopkins University, analysed over 4,200 weight-loss studies to draw their conclusions.
They found that of 32 major commercial weight-loss plans marketed nationwide, only 11 have been rigorously studied in randomised controlled trials - effectively meaning there is insufficient evidence to support whether or not many diets work.
The researchers then looked at the 11 diets - with sufficient evidence available - in depth.
Diets analysed included: Weight Watchers, Atkins, Janny Craig, NutriSystem, HMR, Biggest Loser Club, SlimFast, eDiets, Medifast, Lose it! and Optifast.
Of these 11, the researchers found participants were likely to lose more weight over a 12-month period on just two programmes, than people who were either dieting on their own, got printed health information, or received other forms of education.
The two most effective diet programmes were found to be Weight Watchers and Jenny Craig.
Participants following low-calorie meal replacement plans were found to lose the greatest amount of weight in the first six months of dieting.
However, the only long-term study on such diets suggested there was no benefit of following a meal replacement plan after 12 months.
"Clinicians could consider referring overweight or obese patients to Weight Watchers or Jenny Craig," the report concludes.
"Other popular programs, such as Nutrisystem, show promising weight loss results. However, additional studies evaluating long-term outcomes are needed."
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The researchers hope medical experts will find their study helpful when recommending weight loss programmes to obese patients.
Kimberly Gudzune, assistant professor of medicine and a weight loss specialist at the Johns Hopkins University School of Medicine, said in a statement: "Primary care doctors need to know what programmes have rigorous trials showing that they work, but they haven’t had much evidence to rely on.
“Our review should give clinicians a better idea of what programs they might consider for their patients.”
A previous study published in the Postgraduate Medical Journal suggested the Mediterranean diet could be the most appropriate way to tackle obesity worldwide.
However, the popular diet was not included in the latest Johns Hopkins study.
Whichever diet you chose to follow, monitoring portion size and doing regular exercise is still important when trying to lose weight healthily.
Commenting on the Mediterranean diet research, Dr Alison Tedstone, chief nutritionist at Public Health England, said: "If you are currently overweight you will need to eat less to achieve a healthy weight and be active as part of a healthy lifestyle."
H/T: The MailOnline