Some studies also attracted media attention and marketing hype that may have contributed to the success of specific regimens, Sacks said.
"In this study, we wanted to neutralize these diets," he said. "No marketing. No expectations. All the diets were healthy. We told the participants that experts are completely at odds about which would be better. I think that is a lot of the reason why our study showed they were equal."
Another study, published in July in the New England Journal of Medicine, found that both the Atkins and Mediterranean diets were somewhat more effective than a low-fat diet.
But that study's authors also recommended choosing a diet "according to individual preferences."
Few of the people in the current study strictly adhered to the calorie limits and the composition of their diets, suggesting it is just too difficult to do so, Gardner said. For example, those assigned to consume 35% of their calories as carbohydrates actually consumed an average of 43%, and groups that were supposed to eat a 20%-fat diet averaged 26%. In the end, many of the participants were eating diets that were more similar than dissimilar.
"If the diets are blurring together, then one might expect that the results would be similar," Gardner said. "In reality, trying to follow a low-fat or high-protein diet really has a negative impact on adherence."
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shari.roan@latimes.com
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13
Pounds lost, on average, after six months of dieting.
9
Average pounds lost after two years of dieting.
Source: New England Journal of Medicine
