A biopsychosocial analysis of supplement purchasing behavior in recreational fitness centers: objective BMI, motivational factors, and sex-specific effects.
Source: PubMed, NCBI / U.S. National Library of Medicine
Dietary supplement use in recreational fitness settings is often interpreted through performance-oriented frameworks, yet little is known about how anthropometric status, behavioral engagement, and internalized exercise motives jointly shape real-world purchasing decisions. We examined whether objectively measured BMI, training frequency, current dieting (any type), sex, and motivational structure predict on-site supplement purchase and per-occasion spending in a large gym population. In a cross-sectional sample of = 1,087 fitness center users, height and body weight were measured on site and used to compute BMI, and self-reported training, current dieting (a single yes/no item on following any kind of diet), and purchasing/spending data were collected. Five exercise-related motives underwent exploratory factor analysis, yielding two data-derived dimensions: (F1) broad health-appearance motivation and (F2) muscularity vs. weight-loss polarity. Multivariable logistic regression predicted purchase (yes/no), and linear regression modeled log-transformed spending. Sex interactions and a bootstrap mediation (BMI → F1 → spending) were tested. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). Higher training frequency (OR = 1.79), dieting (OR = 2.14), male sex (OR = 2.05), and F1 motivation (OR = 1.88) independently
Abstract
Dietary supplement use in recreational fitness settings is often interpreted through performance-oriented frameworks, yet little is known about how anthropometric status, behavioral engagement, and internalized exercise motives jointly shape real-world purchasing decisions. We examined whether objectively measured BMI, training frequency, current dieting (any type), sex, and motivational structure predict on-site supplement purchase and per-occasion spending in a large gym population. In a cross-sectional sample of = 1,087 fitness center users, height and body weight were measured on site and used to compute BMI, and self-reported training, current dieting (a single yes/no item on following any kind of diet), and purchasing/spending data were collected. Five exercise-related motives underwent exploratory factor analysis, yielding two data-derived dimensions: (F1) broad health-appearance motivation and (F2) muscularity vs. weight-loss polarity. Multivariable logistic regression predicted purchase (yes/no), and linear regression modeled log-transformed spending. Sex interactions and a bootstrap mediation (BMI → F1 → spending) were tested. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). Higher training frequency (OR = 1.79), dieting (OR = 2.14), male sex (OR = 2.05), and F1 motivation (OR = 1.88) independently predicted greater likelihood of purchase, whereas higher BMI was associated with lower purchase odds (OR = 0.88). A significant Sex × F1 interaction indicated that the F1-purchase association was stronger among women. The purchase model showed good apparent discrimination (AUC ≈ 0.82; estimated on the fitting sample). In contrast, spending per occasion was negatively associated with F1, F2, BMI, and training frequency, suggesting more frequent but smaller transactions among highly motivated exercisers. No indirect BMI → motivation → spending pathway was observed. In recreational gym users, supplement purchasing reflected anthropometric status, behavioral investment, and internalized exercise motives. More engaged and more motivated exercisers were more likely to purchase but spent less per occasion, consistent with structured, goal-congruent consumption, whereas higher BMI was associated with lower purchase odds.