Changes in water and beverage intake and long-term weight changes: results from three prospective cohort studies

OBJECTIVE: To examine the long-term relationship between changes in water and beverage intake and weight change. SUBJECTS: Prospective cohort studies of 50 013 women aged 40-64 in the Nurses’ Health Study (NHS, 1986-2006), 52 987 women aged 27-44 in the NHS II (1991-2007), and 21 988 men aged 40-64 in the Health Professionals Follow-up Study (1986-2006) without obesity and chronic diseases at baseline. MEASURES: We assessed the association of weight change within each 4-year interval with changes in beverage intakes and other lifestyle behaviors during the same period. Multivariate linear regression with robust variance and accounting for within-person repeated measures were used to evaluate the association. Results across the three cohorts were pooled by an inverse-variance-weighted meta-analysis. RESULTS: Participants gained an average of 1.45 kg (5th to 95th percentile, −1.87 to 5.46) within each 4-year period. After controlling for age, baseline body mass index, and changes in other lifestyle behaviors (diet, smoking habits, exercise, alcohol, sleep duration, TV watching), each 1-cup/d increment of water intake was inversely associated with weight gain within each 4-year period (−0.13 kg; 95% CI: −0.17, −0.08). The associations for other beverages were: SSBs (0.36 kg; 0.24, 0.48), fruit juice (0.22 kg; 0.15, 0.28), coffee (−0.14 kg; −0.19, −0.09), tea (−0.03 kg; −0.05, −0.01), diet beverages (−0.10 kg; −0.14, −0.06), low-fat milk (0.02 kg; −0.04, 0.09), and whole milk (0.02 kg; −0.06, 0.10). We estimated that replacement of 1 serving/d of SSBs by 1 cup/d of water was associated with 0.49 kg (95% CI: 0.32, 0.65) less weight gain over each 4-year period, and the replacement estimate of fruit juices by water was 0.35 kg (95% CI: 0.23, 0.46). Substitution of SSBs or fruit juices by other beverages (coffee, tea, diet beverages, low-fat and whole milk) were all significantly and inversely associated with weight gain. CONCLUSION: Our results suggest that increasing water intake in place of SSBs or fruit juices is associated with lower long-term weight gain.