Many Adults Inaccurately Perceive Their Own BMI and Body Size

Summary: Study finds less than 2/3 of people can correctly estimate their BMI, and less than half of people can identify their body size.

Source: Nature

Less than two-thirds of adults can correctly estimate their own body mass index (BMI) and less than half can identify their own body size, according to a study of 744 Polish adults published in Scientific Reports.

Wojciech Gruszka and colleagues calculated the adults’ BMIs between 2010 and 2011 and compared this to participants’ estimates of their own BMI and body size.

Participants, who were 36 years old on average and of whom 60.7% were women, also reported how satisfied they were with their bodies. 21 participants had an underweight BMI (below 18.5 kg/m²), 326 had a healthy BMI (between 18.5 and 24.9 kg/m²), 221 had an overweight BMI (between 25.0 and 29.9 kg/m²) and 176 had an obese BMI (above 30.0 kg/m²).

The authors found that 63.5% participants correctly estimated their own BMI and 49.5% correctly estimated their own body size.

They also found that participants frequently underestimated their own BMI and body size. 17.6% of those with a healthy BMI estimated that they had an underweight BMI, 14.3% of those with an overweight BMI estimated that they had a healthy BMI and 41.6% of those with an obese BMI estimated that they had an overweight BMI. 39.8% of those with a healthy body size estimated that their body size was underweight, 35.7% of those with an overweight body size estimated that they had a healthy body size and 49.9% of those with an obese body size estimated that their body size was overweight.

Only a quarter (25.4%) of participants reported that they were satisfied with their current body size and 65.7% reported wanting their body to be smaller.

Men were significantly more likely than women to underestimate their own BMI and body size, and to be satisfied with their body size.

The authors suggest that the increasing prevalence of obesity and the stigma associated with it may make adults more likely to underestimate their own BMI and body size. Further research is needed to investigate whether psychological interventions addressing body size perceptions could help people better manage their weight, they add.

Abstract

Perception of body size and body dissatisfaction in adults

Self-perception of body size seems to be not always in line with clinical definitions of normal weight, overweight and obesity according to Word Health Organization classification. The effect of self-perception of body size disturbances and body dissatisfaction may be the development of eating disorders, such as anorexia nervosa or binge eating disorder—a major risk factor of obesity development.

Therefore, the study aimed to assess separately the perception of weight status and body size as well as body dissatisfaction in adults with normal weight, overweight and obesity.

The study included 744 adults (452 women; 35.9 ± 12.4 years; 21 underweight, 326 normal weight, 221 overweight, 176 obese) referred to Metabolic Management Center and volunteers. Body size perception and body dissatisfaction were assessed based on Stunkards’ Figure Rating Scale (FRS). Additionally, participants’ were asked: ‘Do you think you are: underweight/normal weight/overweight/obese?’ to assess perception of weight status. Participants’ weight and height were measured to calculate body mass index (BMI) after completing the FRS. Individuals within the overweight BMI range have rated themselves as underweight (1.4%), normal weight (30.8%) and obese (2.8%).

Also individuals within the obesity BMI range have rated themselves as normal weight (2.6%), and overweight (41.6%). Compatibility of self-assessment of weight status with BMI category according to the measured values was moderate—Kappa coefficient was 0.59 (95% CI: 0.54–0.64). Underestimation of weight status was significantly more common among men than women. There were statistically significant differences in the distribution of body dissatisfaction according to the weight in both women and men. Normal-weight subjects less often than overweight and obese were dissatisfied with their own body size.

The degree of body dissatisfaction was greater among women than among men. Adults subjects frequently underestimate their own weight status and body size. Women with overweight and obesity more often than men are dissatisfied with their own body size.