Energy Intake, Non-exercise Physical Activity And Successful Weight Loss: The Midwest Exercise Trial-2 (met- 2)

Changes in energy intake (EI) or non-exercise physical activity (NEPA) may affect the weight loss response to aerobic exercise training.

Purpose To evaluate differences in EI and NEPA between responders (RS; weight loss ≥ 5%) and non-responders (NR; weight loss < 5%) performing 10 months of supervised aerobic exercise training.

Methods Seventy-four overweight/obese (BMI 25-39.9) sedentary young adults (18-30 years) completed a 10-month trial (i.e., ≥ 90% scheduled exercise sessions) of treadmill exercise (5 d.wk-1,70-80% max heart rate, supervised ≥4 d.wk-1) at either 2,000 (n = 37; 19 females) or 3,000 (n = 37; 18 females) kcal.wk-1. EI (kcal.d-1) was measured by picture-plate-waste and NEPA (min.d-1 of sedentary and moderate-tovigorous activity [MVPA]) were assessed by Actigraph GT1M accelerometer over 7 consecutive days at baseline, and at months 3.5, 7, and 10. Participants were instructed to maintain baseline EI and NEPA during the 10 month intervention. T-tests for independent samples and Chi-Squares were used to assess statistical significance.

Results Mean weight change was -9.1 ± 3.7% and -0.7 ± 2.7% for RS and NR, respectively (p < 0.01). There were no significant baseline differences (p = 0.17) in EI (kcal.d-1) between RS (2817 ± 645) and NR (3036 ± 694). However, EI (kcal.d-1) during the intervention was significantly higher (p = 0.02) in NR (3065 ± 805) compared with RS (2669 ± 650). There were no significant differences (p > 0.05) between RS and NR for NEPA (min.day-1) at baseline for either sedentary time (sedentary: RS = 604 ± 81, NR = 600 ± 101) or time spent in MVPA (MVPA: RS = 35 ± 17, NR = 40 ± 24), or during the 10 month intervention (sedentary: RS = 572 ± 63, NR = 571 ± 98), (MVPA: RS = 37 ± 11, NR = 36 ± 12). The proportion of participants classified as RS or NR did not differ by gender (χ2 (1) = 0.10, p = 0.75) or intervention group (2,000 kcal.wk-1 vs. 3,000 kcal.wk-1; χ2 (1) = 1.96, p = 0.16).

Conclusions These results suggest that overweight and obese young adults who fail to achieve clinically significant weight loss (≥ 5%) in response to aerobic exercise training had a higher EI throughout the study than RS while NEPA remains unchanged in both groups. This may support targeting a modest EI deficit (~300-500 kcal.d-1) in exercise NR.

Supported by NIH R01 DK49181