The Evaluation and Assessment of Body Image Perception and Distortion in Men
Creators: name: Mohamed, Sophie
Publisher: name: University of Lincoln
Year: 2023

description: Background: Perceptual body image distortion can be defined as a discrepancy between an individual’s mental representation of their body and their actual body size and shape, and is associated with negative physical and psychological health outcomes. Current methods to assess perceptual body image in men tend to utilise poor imagery, lack ecological validity, focus on Body Mass Index (BMI) variation, and demonstrate little consideration of males-pecific body concerns and ideals. Aims: This thesis presents 6 research studies that aimed to: (i) develop novel visual body stimuli that overcome current limitations of existing measures, (ii) evaluate their reliability and validity in estimating perceptual body image in community-based male samples, and (iii) improve our understanding of the methodological and individual factors that influence visual male body size and weight judgements. Methods and Results: Study 1 evaluated the accuracy of men’s visual body size discriminations using figures ranging in BMI from underweight to obese. This study identified the Just Noticeable Difference (JND) of body size between pairs of figures using a method of constant stimuli, providing evidence of perceptual discriminations consistent with Weber’s law. This informed the development of two male figure scales with a perceptual underpinning for the BMI differentiation between figures. Preliminary evidence for the reliability and validity of these figure scales in estimating men’s current and ideal body perceptions was provided in Study 2. In Study 3, a calibrated mapping between male body shape, fat mass and muscle mass was developed using a database of 3D body scans and body composition measurements. Principal component analysis identified main components of shape variation that were visually modelled as a function of fat mass and muscle mass to develop an interactive body scale. The face validity of this scale was evaluated in Study 4 through fat and muscle ratings of the body model calibrated for points along each body composition dimension. Findings indicated that men were able to visually perceive changes in both dimensions as intended. Preliminary evidence for the reliability and validity of this interactive scale was provided in Study 5. Study 6 investigated the accuracy of categorical male body weight judgements, using 3D body scans presented at 2- and 8-viewpoints. Categorical weight perceptions and weight-loss beliefs were found to be directly related to the BMI and viewpoint of the stimuli, as well as the individual’s sex and attitudinal body image. Conclusion: Several novel visual body stimuli have been developed that present high-quality imagery, wide variation in body size and shape, precise calibration to measurements of body composition, and/or consider visual discriminations of male body weight. Preliminary evidence for the reliability, validity, and suitability of these measures among community-based male samples has been provided, with recommendations for further evaluations and potential modifications. This thesis has also given insights into individual and methodological factors that influence male body weight judgements and supports the visualisation of male body composition in perceptual body image measures.