Weight loss, as a general goal, is difficult for most people to obtain and maintain – “dieting,” in the traditional restrictive sense, requires will power, which is a finite resource. Still, people can and do lose weight if they’re on a manageable regimen. But with so many plans out there, how do we choose? If a study published in the journal Annals of Internal Medicine is any indication, we’re best off leaving that decision to our doctors.

Most people, when choosing between structured diet plans, most people look to either reduce their fat or carbohydrate intake as a means of cutting calories. Research has shown that both techniques can be effective weight loss measures, which is why they were the diets chosen for the study conducted by researchers from the Department of Veterans Affairs and Duke University Medical Center (and others).

The study consisted of two groups of adults. In one group, 105 people were given a choice of weight loss plans (either reduced fat or reduced carbs), while the other group of 102 people were assigned one of the two diets by physicians. 58% of the self-directed group chose the low-carb plan, while doctors assigned the low-fat diet to 52% of the assigned group.

Regardless of the plan, freedom of choice was not kind to the self-directed group. While they were able to lose an impressive 12.6 lbs (on average) over nearly a year, the assigned group lost an impressive 14.7 lbs.

While it would make sense that self-direction would lead to better adherence (since people could choose a diet that allowed for more of their favorite foods), it appears that people who do so still tend to eat too much of those foods. When doctors choose, on the other hand, they can more objectively determine which foods are inhibiting weight loss and assign accordingly.

There’s also the question of authority. People tend to respect the expertise of their physicians, and so they may be more likely to “believe” a diet will work for them even if they find their will power lacking.