Which Commercial Diet Plan is Best?


Looking to lose weight? Any of 14 commercial diet programs analyzed in a recent BMJ study is likely to do the trick in the short term. A recent study in BMJ looked at a range of popular plans such as Jenny Craig, South Beach, and Weight Watchers (now called WW) and found that most produced similar, modest weight loss over six months. And by the one-year mark, any differences between them largely disappeared.

The researchers analyzed data from 121 randomized controlled trials involving nearly 22,000 overweight or obese adults, each of which compared a popular diet to a control diet (generally the participants’ usual diet). Outcomes measured included weight loss and changes in cardiovascular risk factors such as blood pressure, blood cholesterol, and C-reactive protein, an inflammatory marker.

Among individual diets, Atkins, the Zone, and DASH (Dietary Approaches to Stop Hypertension) had the greatest short-term effect on weight loss, with participants achieving average reductions of 8 to 12 pounds after six months, compared to usual diets. Slight reductions in blood pressure (2 to 5 points) were also seen.

But all of the studied diets produced at least some degree of weight loss and blood pressure reduction during the first six months. More importantly, by 12 months the effects of the diets had diminished to the point that the differences between them became negligible, as did differences between categories of diets (low-fat, low-carb, or somewhere in between). A sole exception was the Mediterranean diet, which significantly lowered LDL (“bad”) cholesterol at both six months and 12 months. None of the diets significantly affected HDL (“good”) cholesterol or C-reactive protein.

The researchers concluded that when it comes to weight loss, the differences between these diets were “generally trivial to small, implying that people can choose the diet they prefer from among many of the available diets without concern about the magnitude of benefits.” Or as an accompanying editorial put it, “The extensive range of popular diets analyzed provides a plethora of choice but no clear winner.”

The focus should therefore shift, the editorial added, from which diet one follows to how best to maintain any weight loss achieved. That means finding a healthy eating plan that you can stick with for the long run—one that includes more fruits and vegetables, legumes, and whole grains and less added sugar, refined grains, and saturated fat—as well as committing to regular physical activity.

Of course, the fact that these diet programs produced similar weight loss (by having you consume fewer calories than you burn) doesn’t mean they are similarly healthy. As we reported in April, U.S. News & World Report deemed the DASH and Mediterranean diets the best for healthy eating, out of 35 commercial plans evaluated in 2020.