Purpose: This study aimed to test whether equivalent changes in moderate (walking) and vigorous exercise (running) produce equivalent weight loss under free-living, nonexperimental conditions.
Methods: Regression analyses of changes (Δ) in body mass index (BMI) versus exercise energy expenditure (ΔMET-hours per day, 1 MET = 3.5 mL O2·kg−1·min−1) from survey questionnaires completed at baseline and 6.2 yr thereafter in 15,237 walkers and 32,216 runners were used in this study.
Results: At baseline, walkers spent less energy walking than runners spent running (mean ± SD; males = 2.22 ± 1.65 vs 5.31 ± 3.12 MET·h·d−1, females = 2.15 ± 1.63 vs 4.76 ± 3.03 MET·h·d−1), and walkers were significantly heavier than runners (males = 26.63 ± 4.04 vs 24.09 ± 2.58 kg·m−2, females = 25.44 ± 5.14 vs 21.61 ± 2.49 kg·m−2). During follow-up, energy expenditure declined less for walking in walkers than for running in runners (males = −0.19 ± 1.92 vs −1.27 ± 2.87 MET·h·d−1, females = −0.30 ± 1.93 vs −1.28 ± 2.85 MET·h·d−1). ΔBMI was inversely related to both ΔMET-hours per day run and ΔMET-hours per day walked, but more strongly to ΔMET-hours per day run than walked in men and in heavier women. Specifically, the regression coefficient for ΔBMI versus ΔMET-hours per day was significantly more negative for running than walking in men in the first quartile (differences in slope ± SE: −0.06 ± 0.03, P = 0.01), second quartile (−0.10 ± 0.03, P = 0.001), third quartile (−0.17 ± 0.03, P < 10−8), and fourth quartile of BMI (−0.14 ± 0.03, P < 10−4) and in the fourth BMI quartile of women (−0.32 ± 0.04 kg·m−2 per MET-hours per day, P < 10−17). This represented 90% greater weight loss per MET-hours per day run than walked in the fourth BMI quartile for both sexes. Age-related weight gain was attenuated by running in both sexes (P < 10−6) and by walking in women (P = 0.005).
Conclusion: Although ΔBMI was significantly associated with both ΔMET-hours per day run and walked, the ΔBMI was significantly greater for Δrunning than Δwalking.
Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA
Address for correspondence: Paul T. Williams, Ph.D., Life Sciences Division, Lawrence Berkeley National Laboratory, Donner 464, 1 Cycloton Road, Berkeley, CA 94720; E-mail: email@example.com.
Submitted for publication July 2012.
Accepted for publication October 2012.