by Jennifer LaRue Huget

Consumer Reports raised a stir earlier this month by naming Jenny Craig the queen of all diet programs.

In its latest survey of diet programs (which it’s conducted every other year since 2007), CR ran the numbers on seven popular plans, including Jenny Craig, Slim-Fast, Weight Watchers, the Zone, Dean Ornish’s plan, the Atkins diet and Nutrisystem. CR evaluated the programs’ nutritional value (gauging how closely a week’s worth of menus, chosen by CR from each diet plan, adhere to the standards laid out in the 2010 Dietary Guidelines for Americans), weight-loss data, and short- and long-term adherence rates. The last three were judged according to findings of research published in peer-reviewed journals.

What gave Jenny Craig “the edge” over the others, the report says, was a study published in October 2010 in the Journal of the American Medical Association that showed “a remarkable level of adherence” to the program and an average 8 percent weight loss among the participants after two years.

Slim-Fast came in second place, and Weight Watchers a distant third.

When The Washington Post ran a CR-supplied summary of its report, I was struck by the fact that the two top-rated diets relied heavily on packaged foods. The Jenny Craig program is built around Jenny-Craig brand meals and snacks, and Slim-Fast is all about downing a Slim-Fast shake or bar for both breakfast and lunch. That runs counter to the current nutrition zeitgeist, under which we’re urged eat as much whole, fresh food as possible. Weight Watchers easily accommodates that approach; within its new PointsPlus program (and under the regular points program), dieters can choose whatever foods they like and are encouraged to eat lots of fruit and vegetables.

But when you set out to rate diets (or dishwashers, or whatever), you have to establish some system for objectively evaluating them and stick with the results it produces. CR repeats several times in its report that Jenny Craig might not be the optimal diet for everyone and urges readers to choose the one that best suits them. CR also points out that the PointsPlus program is so new, the results of clinical trials Weight Watchers has conducted to evaluate its efficacy haven’t yet been published so weren’t included in the ratings calculations.

Still, Weight Watchers questioned the findings on several grounds. First, says Karen Miller-Kovach, the company’s chief scientific officer, that JAMA study wasn’t really about the Jenny Craig program at all. It was meant to examine whether people are likely to stick with a diet program if they’re provided free food, and it used Jenny Craig as a means of testing that.

Beyond that, Miller-Kovach says, the menu plan that CR chose to evaluate wasn’t representative of the Weight Watchers program and cast it in the worst nutritional light possible. “The person putting it in made choices, [but] not what we would recommend,” she said.

Nancy Metcalf, senior program editor for Consumer Reports Health, has run all three of CR’s diet-program assessments. When I talked to her late last week about the report and the concerns Weight Watchers raised, she maintained that the evaluation was as fair as it could be given the available data. “I’m sorry that Weight Watchers seems to be so upset,” she said. “I do have a high opinion of their science. But I can’t invent data that I don’t have.”

“Presumably when we do it again in a few years, they’ll have been published,” Metcalf said. “I’m very curious to see how it comes out.”

In a May 18 blog entry on the CR site, though, Metcalf acknowledged that CR’s report should have better described that JAMA study:

“We’ve been doing diet Ratings since 2005, but this year’s installment--our third--is suddenly controversial. The main bone of contention: our inclusion of a 2010 study of our top-rated diet, Jenny Craig. First, let’s acknowledge where the critics have a point. We should have prominently mentioned that participants in the 2010 study, which had a remarkably low dropout rate, didn’t have to pay for the prepackaged meals, snacks, and desserts that are the backbone of Jenny Craig’s program--a freebie that the investigators valued at $6,240 over the course of the two-year study. The monetary value of the free food and counseling in the Jenny Craig trial is indeed a lot higher than, say, the monetary value of the Slim-Fast products, or the cost of membership to Weight Watchers, which were also free to participants in clinical trials of those diets.”

Were you surprised to see Jenny Craig at the top of CR’s list? And how much stock do you put in reports such as CR’s diet rankings, anyway?