Body Composition among Healthy Controls: Association with Eating Disorder Symptoms and Muscular Function

Abstract

Background and Aim: Despite its widespread use, the Body Mass Index (BMI) has significant limitations as a nutritional status indicator. This study aims to advocate for including complementary parameters like body composition (BC) and muscle strength tests for a thorough nutritional assessment. It also explores BC associations with disordered eating behaviour and muscle strength. Methods: The study included 33 participants aged 20-53 from University College London (UCL) or their acquaintances. Participants completed online demographic and Eating Disorder Examination questionnaires (EDE-Q). BC was assessed using a Bioelectrical Impedance Analysis (BIA) device, and muscle strength was measured using mid-upper arm circumference (MUAC), handgrip strength (HGS), and Sit-Up Squat-Stand (SUSS). Results: The median EDE-Q global score was 0.66 [0-4.01], with 30.30% engaging in shape or weight-influencing behaviours. Males scored significantly higher in the restraint subscale (P <0.01). Gender differences were observed in all BIA parameters except fat mass (FM).19.23% of females were classified as low HGS. Significant associations were found between EDE-Q global score and BMI (P < 0.01), FM Index (FMI) (P < 0.05), and MUAC (P < 0.05). Both BMI (β = -0.657, p = 0.001) and Fat-Free Mass Index (FFMI) (β = 0.983, p < 0.001) were significant predictors of HGS. BMI (β = 10.19, p = 0.77) became insignificant for MUAC when FMI and FFMI were included. No significant differences in FFM across BMI categories, but significance was observed in FM between normal weight and both overweight/obese categories (P <0.001). Discussion: This study emphasises the need to supplement BMI with additional measurements and the insights BIA and muscle function parameters provide. It recommends incorporating parameters reflecting nutritional and hydration status within eating disorder (ED) assessments. These measurements should be adopted to improve nutritional assessment in ED settings.