Which Diet Will Help You Lose The Most Weight?

Almost 70 percent of American adults are overweight or obese. At any given time, 51 percent of Americans say they’d like to lose weight, and 25 percent say they’re actively trying to lose weight. It’s not surprising, then, that diets abound.

In fact, it can sometimes seem like there are as many ways to lose weight as there are people trying to lose it — whether with named diets (Atkins, South Beach, Zone, Weight Watchers), generic diets (low fat, low carb, paleo) or fad diets (grapefruits, cabbage soup). In a very broad sense, these all work the same way: They decrease caloric intake, which causes weight loss. More narrowly, some diets make claims about the physiological mechanisms that make one approach preferable to another.

In the end, this isn’t a question for theory, it’s a question for data. The simplest way to figure it out would be to do head-to-head comparisons of all possible diets in large randomized trials. That is, take a group of people who want to lose weight, randomly assign half of them to Atkins and half to South Beach, say, and compare the weight loss in the two groups. Do that again and again and again for all possible diet comparisons, and you’d have your results.

This is rarely done, however. Much more common are randomized trials that compare a single diet to no diet. The reason is pretty simple: Companies selling the diets are funding many of these studies, and thus a major goal of the research is to show that the diet works. A company will find larger weight-loss effects if it compares its diet to no diet than to another diet.

But all is not lost. A recent review paper in The Journal of the American Medical Association does exactly what we want: It reports head-to-head comparisons of different types of diets, and even individual named diets. The researchers use the available studies — which typically compare each diet to no diet — to draw conclusions about how diets compare to one another.

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