(PS14-21) Title: Exploring the Influence of Fear of Weight Gain and Drive for Muscularity on Effort Expenditure in Self-paced Exercise

Endorsement of fear of weight gain (FOWG) and higher drive for muscularity (DFM) have been associated with maladaptive exercise behavior, a risk factor for eating disorder onset. However, limited research has investigated the relationship between FOWG, DFM, and exercise among those with restrictive eating disorders. This study aimed to examine whether individuals who endorsed higher levels of FOWG and DFM, exerted more effort, during exercise. Participants (N=19) with (N=9) and without (N=10) restrictive eating disorder symptoms engaged in a thirty-minute self-paced aerobic exercise task in which the difference between maximum and baseline heart rate was utilized to measure effort. DFM and FOWG were self-reported using the Drive for Muscularity scale and a subscale of the Eating Disorder Fear Questionnaire. Linear regression models were used to analyze FOWG, DFM, and the interaction FOWG x DFM. Results showed that DFM (d = 0.957) had a large effect size and FOWG (d = 0.2183) had a small effect size which suggests that individuals with a higher DFM exerted more effort. The interaction between DFM and FoWG (d = -1.048) also has a strong effect size but suggests that individuals with a higher FOWG and DFM may engage in less intense exercise. Future studies with a larger population sample would be necessary to make further assumptions.