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By Reuters

Researchers said last year that the proportion of overweight U.S. adults trying to lose weight has been shrinking — but newly reanalyzed data suggest the proportion of adults trying to slim down actually grew slightly.

Based on a U.S. survey, researchers had originally reported in JAMA that the proportion of adults who are overweight and obese surged from 53 percent to 66 percent over roughly the past three decades. They also said that over the same period, the proportion of overweight and obese adults trying to lose weight dropped from 56 percent to 49 percent.

But today the authors retracted their paper, noting that they had failed to account for a change in how the survey asked about weight loss efforts starting in 1999. Once researchers accounted for the change in survey questions, they calculated that the proportion of overweight and obese adults actually rose to 58 percent by the end of the study period.

Furthermore, "It looks like the proportion of adults trying to lose weight increased slightly," said senior study author Jian Zhang, a public health researcher at Georgia Southern University in Statesboro, in an email to Reuters Health.

Many news outlets, including Reuters, had reported on the now-retracted study.

"However," Zhang pointed out, "adults today are actually heavier than their counterparts interviewed decades ago. After we mathematically removed the effects from the increased body weight, we found that for overweight adults with exactly the same body weight, adults (surveyed) recently were less likely to have made efforts to lose weight compared to their counterparts (surveyed) decades ago."

The current analysis shares some limitations with the original retracted paper.

Chief among them is that surveying people about their weight and any efforts to shed excess pounds can paint an unreliable picture of how many Americans are obese or trying to lose weight. That's because many people report their weight as lower than it really is, and also report losing more weight than they actually have.

Surveys by nature also aren't controlled experiments designed to prove whether or how any specific weight loss efforts might directly result in people shedding excess pounds.

Doctors often advise people to eat less and exercise more when they want to lose weight, but this can be easier said than done and may not always produce sufficient or lasting weight loss. Weight-loss medications or surgeries may also be an option for some obese patients.

All too often, people who lose weight end up gaining at least some of it back, regardless of the method of weight loss they use.

However, even the revised analysis published today suggests that millions of Americans are still trying to lose weight, said Susan Roberts, a nutrition researcher at Tufts University in Boston who wasn't involved in the study.

"Obesity is a huge problem still, continuing to get worse, and people recognize that and are trying to lose weight," Roberts said by email. "I think the scientific community needs to provide better ways to help people, it is not that people are unmotivated but that it is hard with current methods."