Discriminating against overweight or obese people does not help them lose weight. In fact, the embarrassment, humiliation and stress they feel from such discrimination is likely to cause them to gain weight, according to a British study published online last week in the journal Obesity.

Previous research has shown that people who are stigmatized for being overweight are more likely to engage in behaviors that promote obesity, including problematic eating, avoidance of physical activity and a refusal to restrict their food intake. But, until this new study, there was little evidence on whether such stigmatization was associated with actual changes in body weight.

Study details and key findings

For the study, researchers at the University College London analyzed four years of data collected from 2,944 British adults aged 50 and older who were participating in the ongoing English Longitudinal Study of Ageing. Among the questionnaires filled out by these participants was one that asked about day-to-day discrimination related to their weight, such as how often they felt they had received poorer service than other people in restaurants, stores and hospitals, or been treated as “not clever” by others, or been threatened or harassed. Participants could choose from a range of answers, beginning with “never” and ending with “almost every day.”

The analysis found that 5 percent of the 2,944 participants reported weight-related discrimination — about the same as has been reported in other studies. The people who said they had experienced such discrimination tended to be younger and to have lower incomes than those who said they had not. The more they weighed, the greater the likelihood of discrimination. Only 1 percent of those with a “normal weight” body mass index (BMI) said they had encountered weight-related discrimination compared to 36 percent of those with a BMI that put them in the “morbidly obese” category. Interestingly, men and women reported similar levels of discrimination.

The researchers then compared the participants’ perceptions of weight-related discrimination with changes in their weight. They found a statistically significant association between the two. The people who reported weight-related discrimination gained an average of 2 pounds over the four years of the study, while those who did not lost an average of 1.5 pounds, even after adjusting for differences in weight at the start of the study.

The people who reported weight-related discrimination were also more likely to see their waistline increase slightly over the four years, while those who reported no discrimination saw theirs shrink slightly. (The average difference between the two groups was small, though — slightly less than half an inch.)

In addition, the study found that people who were overweight but not obese at the start of the study but who reported weight-related discrimination were at greater risk of becoming obese after four years than their overweight peers who reported no discrimination.

“Weight discrimination has been justified on the grounds that it encourages obese individuals to lose weight, but our results provide no support for this notion and rather suggest that discrimination exacerbates weight gain and promotes the onset of obesity,” the UCL researchers conclude. “Removing prejudice and blame from weight loss advice might be a better route to promoting weight control.”

‘Stop blaming and shaming’

The researchers cite several possible reasons for why weight discrimination may lead to weight gain. Some have to do with the psychological stress that accompanies such discrimination, which has been shown to trigger particular chemical changes in the brain that increase the desire to eat — particularly high-calorie foods.  People who experience weight-related stigmatization also tend to perceive themselves at being less competent at physical activity, and thus are more likely to avoid it.

Like all studies, this one has its limitations. Most notably, it is an observational study, which means it can show only a correlation between two things (weight-related discrimination and weight gain), not a cause-and-effect connection. Also, the weight-related discrimination in this study was perceived. There is no way of knowing whether it actually occurred.

In addition, although the original sample size for this study was large (almost 3,000 participants), the number of people who said they had experienced weight-related discrimination was small (150). That makes the findings less reliable.

But senior author Jane Wardle, director of UCL’s Cancer Research UK Health Behaviour Centre, says the findings point to a need for all of us to change our attitudes about people who are obese.

“Our study clearly shows that weight discrimination is part of the obesity problem and not the solution,” she said in a statement released with the study. “Weight bias has been documented not only among the general public but also among health professional; and many obese patients report being treated disrespectfully by doctors because of their weight. Everyone, including doctors, should stop blaming and shaming people for their weight and offer support, and where appropriate, treatment.”

You can read the study in full through Obesity’s website.