When we last rated diets four years ago, the winner was the Volumetrics diet, based on eating high-bulk, low-calorie food. In a sense, it's still a winner: The Volumetrics brand is now part of Jenny Craig, which is why we're not rating it separately this time. As for taste, Jenny Craig's prepared food was decent, though not great, as we noted in "Diet taste-off" in our February 2011 issue.
So if you need to lose weight, should you immediately sign up for Jenny Craig? It's obviously worth considering, but if you don't like the idea of eating pre-packaged meals, it might not be for you.
The diet that works is the one you can stay on, says Kathleen Melanson, Ph.D., associate professor of nutrition and food sciences at the University of Rhode Island and director of its Energy Balance Laboratory. "If you're forcing yourself on a diet you hate, it's going to be really hard to stick with long-term," she says.
And these days, choices abound. You can follow the Ornish diet, a near-vegan plan with very little fat, or its diametric opposite, the Atkins diet, which allows almost two-thirds of your calories from fat. Or you can settle somewhere in between with the moderate regimens offered by Weight Watchers and Jenny Craig. As you make your decision, bear in mind some basic realities about weight-loss diets.
Calories, with an asteriskTo lose weight, you have to burn up more calories than you take in, no matter what kind of diet you're on. "The first law of thermodynamics still applies," says Dean Ornish, M.D. But emerging evidence shows that some forms of calories are more filling than others. Protein is the most satiating nutrient, followed by high-fiber grains, fruits, and vegetables.
"We used to believe that it was the same if you ate 200 calories of a cream puff or 200 calories of a chicken breast," says Karen Miller-Kovach, R.D., chief scientific officer for Weight Watchers. "But people would ask, ‘Why do I feel hungry sooner after eating the cream puff?'?"
Diet creators are taking advantage of this new insight to tilt their menus toward foods that will enable you to shed pounds with the fewest hunger pangs. For instance, most of the diets we rate feature liberal amounts of fiber and/or fruits and vegetables.
In late 2010, Weight Watchers unveiled PointsPlus, a major revision of its venerable Points system of calorie-counting, to steer hungry dieters to the most filling foods. That chicken breast will use up only three points of your daily allowance, but the cream puff for dessert will cost you nine points.
(The company has completed clinical trials of the new diet, Miller-Kovach says, but the results haven't been published yet, so we couldn't incorporate them into our Weight Watchers Rating calculations.)
It's OK to go low-carbThe 2010 edition of the U.S. Dietary Guidelines for Americans, which we've used as the basis for the diets' nutrition Ratings (available to subscribers), still frowns on eating 10 percent or more of calories from saturated fat from meat and dairy products and more than 35 percent from fats overall. So the Atkins diet, which is 64 percent fat calories overall and 18 percent saturated fat, ends up with only a Fair nutrition score.
But there's more to the story. Evidence is accumulating that refined carbohydrates promote weight gain and type 2 diabetes through their effects on blood sugar and insulin. "If you have insulin resistance, your insulin may go up to 10 or 20 times normal in order to control your blood sugar after you eat sugar or carbs," says Eric C. Westman, M.D., an associate professor of medicine at Duke University who co-wrote the newest version of the Atkins diet. "But the insulin also tells your body to make and store fat. When you restrict carbs, your insulin goes down and you can burn your body fat, so you eat fewer calories and aren't as hungry."
Isn't it dangerous to eat so much fat? That's still a subject of vigorous scientific debate, but it's clear that fat is not the all-round villain we've been taught it is. Several epidemiology studies have found that saturated fat doesn't seem to increase people's risk of cardiovascular disease or stroke. Other studies suggest that you might be even better off if you replace saturated fat with unsaturated fat instead of with certain carbs, the ones that turn to blood sugar quickly after you eat them, such as white bread and potatoes.
A nutrition researcher, Frank B. Hu, M.D., of the Harvard School of Public Health, recently wrote that he believes "refined carbohydrates are likely to cause even greater metabolic damage than saturated fat in a predominantly sedentary and overweight population."
Moreover, clinical studies have found that an Atkins or Atkins-like diet not only doesn't increase heart-disease risk factors but also actually reduces them as much as or more than low-fat, higher-carb diets that produce equivalent weight loss.
On the other hand, the Ornish Program for Reversing Heart Disease, which includes a low-fat diet along with exercise, stress management, and group support, has proven so effective that Medicare now covers it for cardiac patients.
While scientists sort this out, what's a low-carb dieter to do? Michael L. Dansinger, M.D., assistant professor of medicine at Tufts University and a longtime weight-loss researcher, suggests this middle ground: "a low-ish carbohydrate diet that's high in vegetables and lean protein, including dairy; moderate in fruit; with nonsaturated fat from sources such as olive oil, nuts, avocados, and fish."
Support mattersOur past reader surveys have found that the overwhelming majority of people who succeed at weight loss do it on their own. But don't discount the impact of a good emotional support system.
The Jenny Craig diet, for instance, includes weekly counseling sessions, and group support meetings are the foundation of the Weight Watchers plan. Dean Ornish's program has run support groups for decades to help people follow his rigorous program. "Most people think they're going to have the hardest time with that support group, and yet it's the secret sauce that makes the diet sustainable," he says. "We have people still meeting 25 years after our first study ended."
*Editor's note: We received some criticism for not having mentioned that over the course of the two-year study participants didn't have to pay for the prepackaged food that is the backbone of the Jenny Craig program, which may have improved adherence. Read our response to that criticism as well as our review of the study data, which again placed the Jenny Craig program on top of the Ratings.