The effect of a medical opinion on self-perceptions of weight for Mexican adults: perception of change and cognitive biases

Abstract

BackgroundThis study analysed the relationship between perceived and actual Body Mass Index (BMI) and the effect of a prior identification of obesity by a medical professional for adults using difference in response for two distinct BMI self-perception questions. Typically, self-perception studies only investigate the relation with current weight, whereas here the focus is on the self-perception of weight differences.MethodsA statistical approach was used to assess responses to the Mexican ENSANUT 2006 survey. Adults in the range of BMI from 13 to 60 were tested on responses to a categorical question and a figure rating scale self-perception question. Differences in response by gender and identification of obesity by a medical professional were analysed using linear regression.ResultsResults indicated that regardless of current BMI and gender, a verbal intervention by a medical professional will increase perceived BMI independently of actual BMI but does not necessarily make the identified obese more accurate in their BMI estimates. A shift in the average self-perception was seen with a higher response for the identified obese. A linear increase in perceived BMI as a function of actual BMI was observed in the range BMI < 35 but with a rate of increase much less than expected if weight differences were perceived accurately.ConclusionsObese and overweight Mexican adults not only underestimated their weight, but also, could not accurately judge changes in weight. For example, an increase of 5 kg is imagined, in terms of self-image, to be considerably less. It was seen that an identification of obesity by a health care professional did not improve ability to judge weight but, rather, served as a new anchor from which the identified obese judge their weight, suggesting that even those identified obese who have lost weight, perceive their weight to be greater than it actually is. We believe that these results can be explained in terms of two cognitive biases; the self-serving bias and the anchoring bias.

The Impact of Education and Age on Metabolic Disorders

“…Regarding demographic characteristics, the split by sex is 64% women to 36% men, which is not uncommon in studies in Mexico (60,61). As seen in Table 1, the highest (lowest) educational level groups have a higher (lower) proportion of men.…”

Agreement between self-assessment of body image and measured body mass index in the Brazilian adult population

“…In this scheme, silhouettes 1 and 2 represented underweight; 3 and 4, correct body mass; 5, slightly overweight; 6 and 7, moderately overweight; and 8 and 9, very overweight. Some other studies cite this study but use a 4-group classification: silhouettes 1 and 2; 3 and 4; 5-7; and 8 and 9 [14][15][16][17][18] . In another study, Sutcliffe et al 19 created 3 silhouette groups: normal body mass (1-5); overweight (6 and 7); and obesity (8 and 9) even though the authors cite the 5-silhouette groups created by Bhuiyan et al 13 .…”

“…Statistical analyses consisted of nonparametric statistical procedures to assess the association (Spearman's correlation coefficient) and agreement (simple and weighted Kappa -k) between BMI and the self-assessed body image classifications. The agreement between BMI and two other classifications using 4 categories (silhouettes 1-2; 3-4; 5-7; 8-9, Easton et al 14 ) or 3 categories (silhouettes 1-5; 6-7; and 8-9, Sutcliffe et al 19 ) were performed to ascertain whether the agreement changed when these classifications were used (sensitivity analysis, Velentgas et al 21 ). In addition, prevalence and bias adjusted k (PA-BAK) was calculated as described by Byrt et al 22 .…”

Body misperception: A complex, multifaceted issue to be taken into consideration in obesity

“…Improved detection of body misperception in the form of silhouette distortion, should also be explored in the search to deepen our understanding of this category of misperception, often present in individuals with obesity. Detecting distorted body image based primarily on the use of Stunkard's Figure Rating Scale (99) is relatively easy to implement, but not very sensitive in clinical practice of obesity management, due to weight cue reactivity (100,101) . Therefore, it is clearly necessary to better identify body misperception, in order to propose targeted therapeutic solutions, and thus, better meet the needs of individuals with obesity.…”