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People who gain weight more likely to underestimate their body size

Mon, 09/07/2020 - 12:14
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People with obesity who gain weight have a tendency to perceive their own body size as smaller than it actually is compared to those who maintain a stable weight, according to research following more than 2,000 people with obesity from the Swedish Obese Subjects (SOS) study over ten years.

The study, presented at The European and International Congress on Obesity (ECOICO 2020), also found that while accuracy of body image perception appeared to improve over the years in people who maintained a stable weight (weight change less than 10% after one year follow-up), the degree of body image distortion (the difference between perceived and actual body size) remained in weight gainers (with a 10% or higher weight gain).

"People with obesity often suffer from body image distortion, as they tend to underestimate their own body size", explained study author, Dr Verena Parzer from Rudolfstiftung Hospital Vienna, Austria. "Underestimating body size may be associated with lower body dissatisfaction resulting in a reduced motivation to lose weight."

In the study, researchers examined whether there is a difference in body image perception between weight gainers and weight maintainers in 2,015 patients with obesity (71% females, average age 49 years, average BMI40.3) from the SOS study who received conventional non-surgical weight management over ten years.

Participants were asked to identify their own body figure at the start of the study and three, four, six, eight and ten years later using the Stunkard Scale which consists of silhouette drawings ranging from one being the leanest silhouette to nine the largest silhouette. Body perception index (BPI) was calculated by dividing estimated body size (body mass index (BMI) based on an adjusted Stunkard Scale) by actual BMI.

The outcomes revealed that body image distortion was present in weight gainers as well as in weight maintainers, with both groups underestimating their body size. However, compared to maintainers, weight gainers significantly underestimated their body size at three, four, eight and ten years of follow-up (represented by BPI values of less than 1; table 1). At three years, weight gainers underestimated their actual body size by on average 7.5 BMI units (around 21kg), compared to 6 BMI points (around 17kg) by maintainers.

Body image perception was found to improve over the years in weight maintainers but not in gainers. After ten years, weight gainers underestimated body size by on average 8 BMI units (approximately 23kg) and maintainers by 5 BMI units (approximately 15kg).

The authors acknowledge that the findings show associations, so no conclusions can be drawn about cause and effect. They point to several limitations, including that figure rating scales may not be large enough to represent people with severe obesity; and that body image perception is a continuous variable, while figure rating scales are limited to a number of figures.

"Our results indicate that body image distortion may be associated with the regulation of body weight", concluded study co-author, Dr Magdalena Taube from the University of Gothenburg, Sweden.