The role of free-living daily walking in human weight-gain and obesity

Abstract

Objective: Diminished daily physical activity explains, in part, why obesity and diabetes have become worldwide epidemics. In particular, chair-use has replaced ambulation so that obese individuals tend to sit for ∼2 ½ hours/day more than lean counterparts. Here we address the hypotheses that free-living daily walking distance is decreased in obesity compared to lean subjects and second, experimental weight precipitates decreased daily walking.

Research Design and Methods: During weight-maintenance feeding, we measured free-living walking using a validated system that captures locomotion and body movement for ten days in 22 healthy lean and obese sedentary individuals. These measurements were then repeated after the lean and obese subjects were overfed by 1000 kcal/day for eight weeks.

Results: We found that free-living walking is comprised of many (∼47), short duration (<15 minutes), low velocity (∼1 mph) walking bouts. Lean subjects walked 3 ½ miles/day more than obese subjects (n=10, 10.3 + 2.5 versus n=12, 6.7 + 1.8 miles/day; P=0.0009). With overfeeding, walking distance decreased by 1 ½ miles/day compared to baseline values (−1.5 + 1.7 miles/day; p=0.0005). The decrease in walking that accompanied overfeeding occurred to a similar degree in the lean (−1.4 + 1.9 miles/day; p=0.04) and obese (−1.6 + 1.7 miles/day; p=0.008) subjects.

Conclusions: Walking is decreased in obesity and declines with weight gain. This may represent a continuum whereby progressive increases in weight are associated with progressive decreases in walking distance. By identifying walking as pivotal in weight gain & obesity we hope to add credence to a future that is ambulatory.