Increasing Trends in Incidence of Overweight and Obesity over 5 Decades

Purpose: We evaluated trends in the incidence of overweight and obesity over the past 50 years. Methods: We evaluated trends in the incidence of overweight (25 ≤ body mass index [BMI] <30 kg/m²), obesity (BMI ≥30 kg/m²) and stage 2 obesity (BMI ≥35 kg/m²) from 1950 to 2000 in Framingham Study participants (n = 6798, 54% women). Individuals aged 40-55 years who attended 2 examinations 8 years apart in each decade were eligible. Results: The incidences of overweight, obesity, and stage 2 obesity increased across the decades in both sexes (P for trend <.001). For men, the incidence of overweight rose from 21.8% (95% confidence interval [CI], 17.6-26.5) in the 1950s to 35.2% (95% CI, 28.6-42.5) in the 1990s; of obesity from 5.8% (95% CI, 4.4-7.6) to 14.8% (95% CI, 12.2-17.9); and of stage 2 obesity from 0.2% (95% CI, 0.1-0.9) to 5.4% (95% CI, 4.0-7.2). For women, incidence rates of overweight increased from 15.0% (95% CI, 12.3-18.1) to 33.1% (95% CI, 29.0-37.4); of obesity from 3.9% (95% CI, 2.9-5.3) to 14% (95% CI, 11.6-16.7); and of stage 2 obesity from 1.7% (95% CI, 1.1-2.6) to 4.4% (95% CI, 3.2-6.0). Overall, incidence rates of overweight increased 2-fold and that of obesity more than 3-fold over 5 decades, findings that remained robust upon additional adjustment for baseline BMI in each decade. Conclusions: The incidence of overweight and obesity increased progressively over the last 5 decades, suggesting that the rising trend in prevalence is not a recent phenomenon.