Objectively-assessed physical activity and weight change in young adults: a randomized controlled trial

Abstract

Abstract Background Reductions in physical activity (PA) are common throughout young adulthood and low PA is associated with weight gain. The SNAP Trial previously reported that two self-regulation approaches to weight gain prevention reduced weight gain over a 2-year period in 18–35 year olds. Presented here are secondary analyses examining changes in PA and the relationship between PA and weight change over 2 years. Methods 599 young adults (age: 27.4 ± 4.4 yrs.; BMI: 25.4 ± 2.6 kg/m2) were randomly assigned to 1 of 3 treatment arms: Small Changes (reduce calorie intake by 100 kcals/day & add 2000 steps/day), Large Changes (lose 2.3–4.5 kg initially & increase PA to ≥250 min/wk), or Self-guided (control condition). Small and Large Changes received 10, face-to-face group sessions (months 1–4), and two 4-week refresher courses each subsequent year. Body weight and PA were objectively-measured at baseline, 4 months, 1 and 2 years. Daily steps and bout-related moderate-to-vigorous intensity PA (MVPA: ≥3 METs, ≥10-min bouts) was calculated. Results Changes in bout-related MVPA and daily steps did not differ among treatment groups over the 2-year period (p’s > 0.16). Collapsed across groups, participants gaining >1 lb. (n = 187; 39.6%) had smaller changes in bout-related MVPA at 4 months, 1 and 2 years relative to those maintaining or losing weight (≤1 lb. weight gain; n = 282, 60.4%, p’s 1 lb. did not differ on daily steps (p’s > 0.10). Among participants engaging in ≥250 min/wk. of MVPA at 2 years (n = 181), 30% gained >1 lb. from baseline to 2 years, which was not different from those engaging in 150–250 min/wk. (n = 87; 36%; p = 0.40), but this percentage was significantly lower when compared to those engaging in 150 min/week of MVPA is needed for weight gain prevention and that increasing MVPA, rather than steps, should be targeted. Trial registration www.clinicaltrials.gov (NCT01183689). Registered Aug 13, 2010.

Keywords

• Weight gain
• Young adulthood
• Exercise
• Physical activity
• Body weight