If you're trying to lose weight, you may want to let your doctor choose your diet plan, rather than choosing your own: In a new study, people who chose the type of diet they wanted to follow lost less weight than the people who followed a specific diet assigned by their doctor.
In the study, 105 people who were trying to lose weight were allowed to choose between a low-carbohydrate diet and a low-fat diet. Among these participants, 58 percent chose a low-carb diet, and 42 percent chose a low-fat diet. For a separate group of 102 people, the researchers assigned a low-fat diet to 52 percent of the people and a low-carb diet to the other 48 percent.
After following their diet plans for almost a year, the people who were allowed to choose their own diet plan lost 12.6 lbs. (5.7 kilograms) on average, whereas the people in the group whose doctors assigned their diets lost 14.7 lbs. (6.7 kg) on average.
Previous research comparing the effectiveness of low-carb diets and low-fat diets has shown that both diets can work, as long as people adhere to them, said study author Dr. William Yancy, of Durham VA Medical Center in Durham, North Carolina. The researchers wanted to conduct the study because "it felt intuitively that if you let people choose their diet based on their food preferences (…) that they would stick to the diet better," he said.
The researchers figured that the people who stuck to their diets better would lose more weight, so they were surprised to find that the people who chose their diets actually lost less weight than the people whose diets were picked for them. [7 Biggest Diet Myths]
The researchers think the reason people may lose less weight when they choose their own diet plan is that they may choose a plan that includes more of the foods they like to eat, which, in turn, makes it difficult for them to scale back on these foods, Yancy said.
"People might adhere to a diet better if it has foods that they prefer, but they actually might overeat those foods, and that might be to their detriment," Yancy told Live Science.
Conversely, "if the diet that they are following eliminates some of the foods that they prefer, then they might actually lose more weight," he said.
However, he noted that, although the people in the study who chose their diet plan did not lose as much weight as those who had the decision made for them, this does not mean that doctors should not present their patients with different diet options."It is just that [patients] might not be the right people to choose among those options," Yancy said.
Future research should examine how to match people with the diets that would work best for them, by considering such factors as their metabolic profiles or genetics, instead of their food preferences, the researchers said.
"I think we do have enough information to know that different diets work differently in different people; we just need to get better at pairing the diet with the person," Yancy said.
The new study was published today (June 15) in the journal Annals of Internal Medicine.