Body size estimation in obesity: a systematic review and meta-analysis

Previous research about body size estimation in obesity reported heterogeneous results. This might be related to the fact that the tasks adopted explored different body representations. Classifying the previous studies according to the specific body representation probed (i.e. implicit, explicit or both) might clarify discordant findings. A systematic review and meta-analysis of research articles assessing body size estimation in individuals affected by obesity compared with healthy weight individuals were performed in PubMed and Web of Science. Additional records were identified by reference lists inspection. The last search was run in May 2021. Two independent authors performed data extraction according to predefined criteria. Both groups either overestimated or underestimated the implicit body representation depending on the task used and the body part considered. Conversely, the explicit representation of the body was mainly overestimated by both individuals with obesity and healthy weight. In tasks relying on both these representations, overestimation and underestimation were reported in both groups, possibly depending on the degree of which each procedure relied on the explicit and/or implicit representation of the body. According to the meta-analysis, individuals with obesity tended to be significantly less accurate in body size estimations than participants with healthy weight. We confirmed that heterogeneous findings in body size estimation in obesity are related to the adoption of different tasks, which likely involve different body representations. We discussed the role of body dissatisfaction and altered somatosensation in the lower accuracy observed in obesity.