Sixty one healthy adults (18–35 y) completed a supervised resistance training (RT) program (3 d/wk) with protein supplementation for nine months. Subjects were randomly assigned to a whey protein concentrate (WP, n=18), soy protein isolate (SP, n=21) or carbohydrate (CHO, n=22) supplementation group (20 g/d). Participants were advised to follow a diet providing adequate energy and ~1.0 g protein/kg body weight plus supplement. Resting metabolic rate (RMR), total triiodothyronine (TT3) and total thyroxine (TT4) were measured. RMR significantly increased from baseline to the end of the study (p=.002) with the largest increase observed in WP (108±177 kcal/d) followed by SP (72±109 kcal/d), and CHO (44±180 kcal/d). The RMR changes were not significant between groups. Plasma TT3 was different at three months of RT between WP and SP (0.45±0.18 ng/ml, p=.048), no other differences were observed at six or nine months. Plasma TT4 decreased from baseline to three months in CHO (−1.55±0.22 μg/dl, p=.000) and WP (−1.37±0.42 μg/dl, p=.025). TT4 values were back to baseline at six months in WP and at nine months in CHO. There were no associations between the changes in RMR and TT3 or TT4 in any group. These results suggest that a nine month progressive RT program significantly increases resting RMR. [Supported by National Dairy Council, USA].