The Relationship Between Light Physical Activity and 10-year Weight Change in 2,868 U.S. Adults: An NHANES Investigation

The prevalence of obesity has steadily increased for the past several decades. About 13.4% of Americans aged 20-74 had obesity in 1960-1962 and the prevalence jumped to 42.8% in 2017-2018—more than a 3-fold increase. PURPOSE: The aim of this study was to evaluate the relationship between time spent in light physical activity (LPA) and 10-year weight change in a random sample of 2868 women and men representative of the U.S. adult population. METHODS: Cross-sectional data was used from the National Health and Nutrition Examination Survey (NHANES) from the 2003-2006 data cycles. Participants were limited to non-pregnant U.S. adults ages 36-70 yrs. Physical activity was objectively assessed by NHANES with the ActiGraph accelerometer, AM-7164. Participants were instructed to wear the accelerometer on the right hip for 7 consecutive days, excluding water activities and bedtime. Body weight was measured in the NHANES mobile examination center. Subjects also self-reported their body weight from 10 years prior. Weight change was calculated as the difference between one’s current weight and one’s weight 10 yrs earlier. Minutes per day of light physical activity (LPA) was divided into tertiles. Age, sex, race, home ownership, smoking, alcohol use, time spent in moderate activity (MPA), and time spent in vigorous activity (VPA), and strength training minutes, were statistically controlled. RESULTS: Mean accelerometer wear-time was 14.3 hrs per day. On average, U.S. adults spent 349 minutes each day in LPA, 23 min. in MVPA, and 486 min. in sedentary behavior. Mean (±SE) 10-yr weight gain was 6.4±0.4 kg. After controlling for differences in the demographic covariates, adults with low levels of LPA gained 5.9 kg and those with moderate levels gained 6.0 kg, whereas those with high levels (upper one-third) of LPA, gained 3.8 kg (F=5.9, P=0.0071) over the 10 yrs. After adjusting for all the covariates, the relationship remained significant (F=3.6, P=0.0198). Adults with high levels of LPA gained significantly less weight (+2.9 kg) than those with moderate levels (+4.7 kg) and those with low levels of LPA (+4.6 kg). CONCLUSION: In the U.S., adults who engaged in the highest levels (upper one-third) of LPA gained significantly less weight over 10 years compared to those who spent less time in LPA.