Weight Watchers, Slim-Fast and the “Zone” top the list of nine popular diet plans studied by Consumer Reports magazine, the latest issue shows.

Weight Watchers International Inc. ranked highest on the basis of published clinical research, nutritional analyses and U.S. dietary guidelines, said the monthly magazine best known for comparing prices and performances of cars.

“A balanced, Low fat diet plus weekly meetings give this large commercial weight loss program the highest long-term adherence rate of any diet in our analysis,” Consumer Reports said.

Slim-Fast, a line of meal-replacement bars and shakes made by British food company Unilever Plc , was in the No. 2 slot, while the low-carb “Zone” diet, developed by Dr. Barry Sears, came in third.

The low-fat, vegetarian Ornish plan, created by diet guru Dr. Dean Ornish, came in fourth.

Two separate phases of the Atkins diet, which popularized the so-called “low-carb lifestyle” by discouraging consumption of bread and pasta in favor of proteins like meat and cheese, fell into the fifth and sixth slots - the study’s lowest rankings.

Atkins Diet: The Basics
The core concept of The Atkins Diet is Dr. Atkins’ theory that over-consumption of and hypersensitivity to carbohydrates is the root of our problem with being overweight.

The principle he bases his plan on says that it is the way your body processes the carbohydrates you eat - not how much fat you eat - that causes you to gain weight.

Atkins says that many overweight people may be “insulin resistant,” that is, the cells that convert carbohydrates into glucose (which becomes energy) do not work correctly. While most diet experts say that not everyone who has a weight problem is insulin resistant, Atkins says it is more likely than not.

That’s where Dr. Atkins’ plan comes in: What is the remedy to insulin resistance or over-consumption of carbohydrates? Begin restricting yourself, particularly from eating the “bad” ones like those found in processed, pre-packaged and junk foods (cookies, sodas, etc.) and prepare to follow this high-protein eating plan.

Consumer Reports said Atkins “worked very well in the short term ... but its nutritional deficiencies - too much fat, too little fiber, too few fruits - depressed its overall rating and might have a negative effect on some dieters’ health.”

Responding to the report, Colette Heimowitz, vice president of education and research at Atkins Nutritionals Inc., the diet’s parent company, said Consumer Reports used “inaccurate calculations” that misrepresented the longer-term phase of the Atkins diet. The report also ignored “a large body of research” that has “shown no ill health effects” from following the Atkins diet, Heimowitz said.

Consumer Reports also studied the eDiets, Jenny Craig, South Beach Diet, and Volumetrics weight loss regimens, but did not rank those programs “because they lacked data from large, long-term published clinical trials.”