Advertisements for weight-loss programs usually show cheery dieters delighted to be shedding their burden of excess pounds, but a new study finds that in the real world, over time, weight loss may be linked with worsening mood.
UK researchers following about 2,000 overweight and obese adults over four years found that people who lost 5 percent or more of their body weight had improved physical health but higher rates of depression.
“We know that weight loss is so hard to achieve or maintain, so we wondered whether part of the explanation might be that the psychological effects aren’t entirely positive,” said Jane Wardle, the study’s senior author and a researcher at University College London.
“Our study isn’t definitive because we were comparing people in the general population who had lost weight with people who hadn’t – it wasn’t a randomized trial,” Wardle told Reuters Health in an email.
But, she added, the results indicate that although weight loss brings health benefits, it may be a bit of a psychological struggle.
Wardle noted that many articles and products on weight loss imply that it will immediately make people feel better, but these findings show that may not be true.
Overweight and obese adults are often told to lose weight to improve their health. And according to a 2012 survey, about 60 percent of obese adults in the U.S. had tried to lose weight during the past year.
For overweight and obese people, weight loss is well known to lower the risks for a range of physical illnesses. But research on the psychological benefits has been mixed, Wardle and her coauthors write in the journal PLOS One.
The researchers used information for 1,979 overweight and obese men and women who were part of the English Longitudinal Study of Ageing, a large population study of U.K. adults age 50 and older.
Nurses measured the height, weight and waist circumference of each participant, and questionnaires were used to assess mood. In addition, blood pressure and serum triglycerides were measured to determine cardiovascular risk.
None of the participants was depressed when the study began.
Since this was an observational study, the researchers didn't give instructions or advice to lose weight, but they recorded whether or not the participants said they intended to lose weight.
After four years, 14 percent of the participants lost at least 5 percent of their initial body weight, or about 15 pounds on average. Another 71 percent had kept their weight stable, and 15 percent had gained more than 5 percent of their initial weight - about 14 pounds on average.
The average age was highest in the weight-loss group, and there were more men and more wealthy participants in the weight-stable group. People in the weight loss group also tended to have more weight to lose than their counterparts.
Psychological wellbeing deteriorated in all three groups, but members of the group that lost weight were 80 percent more likely to be depressed than the people who maintained their weight.
The study doesn’t prove that losing weight caused depression, the authors note. It’s possible that depression caused some people to lose weight or that neither caused the other and that something else the participants had in common was responsible for the weight loss or the depression.
But Wardle said she has some idea why weight loss might be connected with depression. “In order to lose weight, a person has to eat less than they would like to, and possibly less than people around them, and losing out on the pleasure of food is bound to be hard, even if there are compensations in terms of dropping a dress size and improving your health,” she said.
“Maybe if we were more honest about the fact that it won’t necessarily make you feel good in the short-term, people would gear themselves up for the challenge,” Wardle added.
She and her colleagues suggest in their report that more investigation into the emotional consequences of weight loss is needed.
Dr. Ronald Sha, the medical director of the Duke University Diet and Fitness Center in Durham, North Carolina, told Reuters Health he is puzzled by the findings, based on his own experience at his clinic.
“We see people for a more abbreviated time - a matter of weeks, but virtually everyone who leaves the (Duke Medical Center) leaves here in a much better mood,” said Sha, who wasn’t involved in the new study. “Everybody sees considerable improvement in their physical function, they see considerable improvement in their mood and they all lose weight.”