Exploring inter-individual variability in the thermic effect of feeding among women approaching menopause

Little is known about the factors that influence inter-individual variability in the thermic effect of food (TEF). Factors such as age, physical activities, insulin resistance and body weight and composition have been proposed as potential predictors, but findings remain inconsistent. TEF may also be influenced by hormonal status in females. Therefore, this study aimed to explore potential physiological and dietary predictors of TEF in a well-phenotyped cohort of females approaching menopause. This study is a secondary analysis of the MONET study. Eighty-six females had complete data for all predictors included in the analyses: fat mass (kg), resting energy expenditure (REE), VO₂peak, fasting glucose, follicle-stimulating hormone and habitual protein intake. Stepwise multiple linear regression analyses were conducted to identify predictors of TEF. Mean TEF over the 180-min measurement period was 33 (sd 8·7) kcal. Habitual daily protein intake was the only consistent significant predictor of TEF across regression models (B ≈ 0·12-0·14 kcal·g^-1, β ≈ 0·23-0·24, P ≤ 0·04), explaining 6 % of the variance (R² = 0·060). Inclusion of fat mass, REE, VO₂peak, fasting glucose or follicle-stimulating hormone did not meaningfully improve model fit. These findings suggest that TEF may represent a relatively stable physiological trait, with modest contributions from habitual dietary protein intake, and that additional, unmeasured factors may contribute to inter-individual variability.