Â鶹ӰÊÓ

A new study comparing the controversial Atkins diet to three other regimes found that not only was it the most effective at weight loss among overweight women, it did not increase blood pressure or cholesterol.

But although the study may tip the scale in Atkins' favour, critics say it also shows that shedding pounds is difficult, and it's even more of a challenge to keep them off.

At the end of the 12-month period, overweight women following the Atkins diet had lost the most amount of weight in comparison to women on three competing regimes, according to Stanford University's A to Z Weight Loss Study released Tuesday.

Not only was the most weight lost on Atkins, there were no indications of undesirable side-effects, according to the study, which was published by the Journal of the American Medical Association.

"So many people have been asking questions about diets for years. We think it's time to give them some answers," lead author Christopher Gardner, professor of medicine at Stanford University's disease prevention research centre in California, told British newspaper The Times.

"We have an epidemic of obesity that's still on the rise, and the ideas of our best and brightest people haven't been able to change that."

The Atkins diet, developed by the late Dr. Robert Atkins in the 1970s, cuts carbohydrates such as bread and sugar and boosts consumption of foods higher in fat, like cheese and bacon, instead of bread and pasta.

The Ornish Diet, which was devised by a doctor treating heart disease, advocates a high-fibre, low-fat vegetarian diet.

The Zone Diet, which was created by Dr. Barry Sears, aims at achieving stable blood sugar levels and eicosanoids.

The LEARN (Lifestyle, Exercise, Attitudes, Relationships and Nutrition) diet is the U.S. government's recommendation of a low-fat, high-carbohydrate diet.

These other diets have come into prominence as interest in Atkins waned amid increasing concern that Atkins devotees consume too much fat, which could lead to high cholesterol and blood pressure.

In its stead, other regimes have gained popularity, such as the G.I. diet, based on eating specific foods that release glucose slowly into the bloodstream.

During the study, 311 overweight women, aged 19 to 50, were divided into four groups. Each of them followed a different diet for one year -- the Atkins, the Zone, the Ornish and LEARN.

Under the Atkins diet, the women tried to eat no more than 20 grams of carbohydrates a day for the first two to three months. For the rest of the diet, they aimed to consume 50 grams per day or less.

The women who followed the Zone diet aimed to eat food containing 40 per cent of carbohydrates, 30 per cent protein, and 30 per cent fat.

The third group that was assigned the LEARN diet, aimed to include 55 to 60 per cent of daily calories from carbohydrates, and less than 10 per cent of calories from saturated fat.

The rest of the women who were following the Ornish diet tried to eat no more than 10 per cent of calories from fat.

Each regime advises a different amount of carbohydrate consumption. For example, the Atkins diet recommends the lowest level, while the Zone diet advises slightly more.

After a year's time, the 77 women in the Atkins group lost an average of 10.3 pounds, about twice as much as those on the Ornish diet (4.8 pounds) and LEARN regime (5.7 pounds), while those on the Zone lost an average of 3.5 pounds.

The Atkins dieters also saw the most improvements in body mass index, triglycerides, HDL (good) cholesterol and blood pressure -- all indications of improved health.

Cholesterol

However, the Atkins diet was not better than the others when it came to decreasing the LDL (bad) cholesterol. After a period of two months, the LEARN diet lowered the LDL cholesterol by 7.3 per cent while the Ornish regime reduced it by 10 per cent. At the end of their regimes, however, the LDL-reducing impact had diminished.

In contrast, the Atkins dieters saw their LDL cholesterol rise by 2 per cent after two months.

"While questions remain about long-term effects and mechanism, a low-carbohydrate, high-protein, high fat diet may be considered a feasible alternative recommendation for weight loss," the study's authors said

The authors also said that concerns about adverse metabolic effects relating to the Atkins diet were not substantiated within the 12-month study period.

They were unable to determine, the researchers said, whether the benefits were attributable to the low-carbohydrate intake or other aspects of the diet, such as high-protein consumption.

Long-term impact

The long-term impact of the diets is unclear as the study did not follow dieters after 12 months. Among Atkins dieters, some women gained some weight back between six and 12 months.

"If you look at the data in the study, the women following the Atkins diet actually lost more weight at six months than they did at 12 months -- so they actually gained a little bit of their weight back," Nutritionist Leslie Beck told Â鶹ӰÊÓnet.

"They waned or strayed from their diet more so than the women in the other diet groups, suggesting that in the long term it may not be the easiest plan to follow."

Dr. Yoni Freedhoff of the Bariatric Medical Institute, meanwhile, said the amount of weight lost in a year by study participants -- even those on the Atkins diet - is hardly impressive.

Freedhoff advocates hunger prevention: eating every two to three hours, with some protein in every meal or snack, and being aware of calories.

"At the end of the day, weight's not about protein, it's not about carbs, it's not about fat -- it's about calories," he told Â鶹ӰÊÓnet from Ottawa. "So you should probably take a peek and see how many you're having."

Freedhoff said cutting out carbs completely is unnecessary and too difficult to maintain over the long term.

"The fact is, if you don't like the way you're living as you're losing weight, you're going to gain that weight back," he said.

Beck also said that permanent weight loss requires people to not just commit to changing their eating behaviours, but to incorporate exercise into their lives to burn off the calories and keep the weight off.

"We know that's a critical factor in maintaining weight loss," she said.

Some critics also say the study does not close the chapter on the debate as the researchers did not consider other popular diets such as the South Beach, G.I. (glycemic index), and Mediterranean regimes.