The study, which was carried out by researchers at Duke University between May 2011 and June 2012, involved just over 200 patients at Veterans Affairs medical centers. All of the participants had a body mass index of 30 or higher, and their average age was 55. Three in four participants were men, and roughly half were black.
Of the participants, roughly half chose their diets while the other half was provided with a diet regimen prepared by the study’s organizers.
Both groups saw significant weight loss. The group that chose their diet lost, on average, about 12.6 pounds, or 5.6 per cent of their body weight. However, the group provided with a prepared diet lost more weight: 14.7-pounds, on average, or 6.2-percent of their body weight.
The Duke researchers believe the people who chose their diet picked foods they preferred and were, therefore, more likely to overeat. Meanwhile, the participants on the assigned diet may have benefited from what the researchers call the “personal trainer effect”–meaning they felt an obligation to satisfy those who directed them.
Looking forward, the Duke team believes studies should try to connect diet with other important factors in weight loss. “Future research might examine matching patients to their optimal diet on the basis of other characteristics (such as metabolic profile or genetics) instead of their preferences,” the researchers noted.
