The impact of resistance training has not been thoroughly examined in overweight older adults undergoing weight loss. Subjects (n = 27) were overweight and obese (BMI 31.7 +/- 3.6 kg/m(2)) older (age 67 +/- 4 years) adults and were randomized into either a 10-week Dietary Approaches to Stop Hypertension for weight loss diet (DASH, n = 12) or DASH plus moderate intensity resistance training (DASH-RT, n = 15). Outcomes included weight loss, total body and mid-thigh composition, muscle and physical function. There were no significant weight loss differences between the DASH-RT and DASH groups (-3.6 +/- 0.8 vs. -2.0 +/- 0.9%, p = 0.137). The DASH-RT group had a greater reduction in body fat than the DASH group (-4.1 +/- 0.9 vs. -0.2 +/- 1.0 kg, p = 0.005). The DASH-RT group had greater changes in lean mass (+0.8 +/- 0.4 vs. -1.4 +/- 0.4 kg, p = 0.002) and strength (+60 +/- 18 vs. -5 +/- 9 N, p = 0.008) than the DASH group. There were favorable changes in mid-thigh composition variables in the DASH-RT group that were different than the lack of changes observed in the DASH group, except for intermuscular adipose tissue. Both groups experienced decreases in 400-m walk times showed (DASH -36 +/- 11 s, DASH-RT -40 +/- 7 s) with no differences between groups. Moderate intensity resistance training during weight loss appears to improve fat mass and thigh composition, but weight loss only does not. However, global measures of physical functioning may improve with a weight loss-only program.