The controversial low-carbohydrate Atkins diet has scored well in a major US analysis.
Atkins is easy to follow
The Stanford University study, of more than 300 women, rated Atkins ahead of three other popular diets.
Those who followed Atkins for a year lost the most weight, and recorded the most beneficial effect on their cholesterol and blood pressure levels.
However, the Journal of the American Medical Association study did not look at possible long-term health problems.
Critics of low-carbohydrate diets say they can store up problems for the future.
The Stanford team found no evidence of such problems emerging after a year on the Atkins diet - but admitted potential long-term problems could not have been identified in a 12-month study.
They also accept that several basic vitamins and minerals can be difficult to get in adequate amounts from a very-low-carbohydrate diet.
However, researcher Dr Christopher Gardner said: "Many health professionals, including us, have either dismissed the value of very-low-carbohydrate diets for weight loss or been very sceptical of them.
"But it seems to be a viable alternative for dieters."
The researchers randomly assigned 311 women to one of four diets:
- Atkins diet: the lowest carbohydrate diet
- The Zone diet: also low-carbohydrate, focuses on a 40:30:30 ratio of carbohydrates to protein to fat, a balance said to minimize fat storage and hunger
- The LEARN diet: Low in fat and high in carbohydrates
- The Ornish diet: Very high in carbohydrates and extremely low in fat
The study was set up to mimic real-world conditions. The participants attended weekly diet classes for the first eight weeks, and received a book outlining how to follow their specific diet.
They were then left to their own devices to follow the diets as best they could.
Easy to follow
At the end of the year, the 77 women assigned to Atkins had lost an average of 10.4lbs (4.7kg).
The LEARN group lost an average of 5.7lbs (2.6kg), the Ornish group 4.8lbs (2.17kg), and the Zone group 3.5lbs (1.59kg).
The Atkins group also registered larger decreases in harmful cholesterol, and blood pressure levels, and a larger rise in beneficial cholesterol levels.
However, the Atkins group were also more likely to shed weight quickly, but begin to put some of it back on towards the end of the study.
Dr Gardner said the key could be that the Atkins diet was the easiest to follow.
"It's a very simple message," he said. "Get rid of all refined carbohydrates to lose weight."
He said the fact that people following Atkins tended to eat higher levels of protein also helped, as this was likely to make them feel full more quickly.
Dr Frankie Phillips, of the British Dietetic Association, said it was not surprising that Atkins led to weight loss, as it was a very prescriptive diet, which was likely to lead to a reduction in calorie intake.
However, she said many other diets were likely to achieve the same effect, and the long-term health impact of Atkins remained unclear.
"Our concern about low-carbohydrate diets is that they severely limit the amount of healthy wholegrain foods that people can eat," she said.
"If a diet excludes particular food groups then people should consider whether it is likely to provide all the nutrients the body needs to function properly."