An editorial in the same journal challenges the study's optimistic tone, pointing out that subjects were not sticking to the specified calorie allowance based on their eventual weight gain, nor were they eating meals in the specified proportions of nutrients.
Tests showed that, over time, the protein intake between the high-protein diet and the average-protein diet groups, which should have differed by 10 percent, dwindled to a 1 to 2 percent difference. The highest and lowest carbohydrate diet groups, which should have differed in carbohydrate intake by 30 percent, differed by only 6 percent.
Martijn Katan, the author of the editorial, said the data suggest that failure to lose weight is a behavioral problem bolstered by the nutritional environment of the U.S.
"We do not need another diet trial; we need a change of paradigm," Katan said.
While the study authors agreed that creating a healthier food environment is a crucial goal in a country where 78 million people are obese -- 12.5 million of whom are children, according to the Centers for Disease Control and Prevention -- they denied Katan's statement that individual efforts at weight loss are not significant.
"We're never going to have a perfect environment and people have to be willing to make those changes," Loria said. "I don't think you can be successful unless you have both."
In terms of dieting, community support can be critical but choosing a plan is up to an individual, and the hardest part of losing weight may be accepting the hunger factor.
Past studies have shown that calorie restriction is the biggest determining factor for successful weight loss, even greater than exercise.
"There are those with unrelenting optimism, who think [dieting] is going to get easier," said Marlene Schwartz, deputy director of the Rudd Center for Food Policy and Obesity at Yale University. "But if you are eating fewer calories than you are burning, you are going to be hungry."
But the study's findings encourage experimentation, Sacks said, and the flexibility to find the best balance of calorie restriction and satisfaction for individuals.
"The hardest thing, having been born and raised in America, [was that] I thought I was entitled to eat as much as I wanted whenever I wanted and I would stay the same weight," Termini said. "But you can't do that. And it's not healthy."
ABC News' Lauren Cox contributed to this report.
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