Diet Soda Intake Is Associated with Long-Term Increases in Waist Circumference in a Biethnic Cohort of Older Adults: The San Antonio Longitudinal Study of Aging

Objectives: To examine the relationship between diet soda (DS) intake (DSI) and long-term waist circumference (WC) change (ΔWC) in the biethnic San Antonio Longitudinal Study of Aging (SALSA).

Design: Prospective cohort study.

Setting: San Antonio, Texas, neighborhoods.

Participants: SALSA examined 749 Mexican-American and European-American individuals aged 65 and older at baseline (baseline, 1992–96); 474 (79.1%) survivors completed follow-up 1 (FU1, 2000–01), 413 (73.4%) completed FU2 (2001–03), and 375 (71.0%) completed FU3 (2003–04). Participants completed a mean of 2.64 follow-up intervals, for 9.4 total follow-up years.

Measurements: DSI, WC, height, and weight were measured at outset and at the conclusion of each interval: baseline, FU1, FU2, and FU3.

Results:  Adjusted for initial WC, demographic characteristics, physical activity, diabetes mellitus, and smoking, mean interval ΔWC of DS users (2.11 cm, 95% confidence interval (CI) = 1.45–2.76 cm) was almost triple that of nonusers (0.77 cm, 95% CI = 0.29–1.23 cm) (P < .001). Adjusted interval ΔWCs were 0.77 cm (95% CI = 0.29–1.23 cm) for nonusers, 1.76 cm (95% CI = 0.96–2.57 cm) for occasional users, and 3.04 cm (95% CI = 1.82–4.26 cm) for daily users (P = .002 for trend). This translates to ΔWCs of 0.80 inches for nonusers, 1.83 inches for occasional users, and 3.16 for daily users over the total SALSA follow-up. In subanalyses stratified for selected covariates, ΔWC point estimates were consistently higher in DS users.

Conclusion: In a striking dose-response relationship, increasing DSI was associated with escalating abdominal obesity, a potential pathway for cardiometabolic risk in this aging population.