Dietary prescription adherence and non-structured physical activity following weight loss with and without aerobic exercise

Objectives: To compare the effects of weight loss with and without exercise on 1) dietary prescription adherence and 2) non-structured activity in postmenopausal women.

Design: Longitudinal study.

Setting: Clinical research setting with facility based exercise and nutrition education.

Participants: Overweight and obese women, 45–76 years old.

Intervention: 6 months of weight loss alone (WL; N=38) or with aerobic exercise (AEX+WL; N=41).

Measurements: Cardiorespiratory fitness (VO₂max), resting metabolic rate (RMR), seven day food intake, and physical activity (by Actical accelerometers worn in a subset subgroup: WL: N=10; AEX+WL: N=15) were assessed before and after the interventions.

Results: Both interventions resulted in similar weight loss (~9%) and no signficant changes in RMR, while only the AEX+WL group improved VO₂max (~10%). At baseline, the AEX+WL group consumed slightly more protein than the WL group (P<0.01). Macronutrient intake did not change following AEX+WL, but the WL group decreased their fat intake and increased their carbohydrates and protein intakes (Ps<0.05), which resulted in similar macronutrient intakes between groups post-intervention. Weekday total activity counts decreased 22% (P<0.05) following WL. This change tended (P=0.07) to be different than the lack of change in non-structured activity observed following AEX+WL.

Conclusion: Although similar dietary adherence was observed, these data suggest that postmenopausal women undergoing weight loss may benefit from the addition of exercise to prevent the decline in non-structured activity observed following weight loss alone.