Shift in the composition of obesity in young adult men in Sweden over a third of a century

Abstract

Objective:

To assess whether the composition of the obese category (body mass index (BMI)⩾30) has changed during the last one-third of a century in young adult men.

Design:

Retrospective study of 1 580 913 men (18.3±0.4 years) representing 82% of the Swedish male population at military conscription age between 1969 and 2005. Measured height and weight were used to define moderate and morbid obesity as BMI 30–34.9 and ⩾35, respectively. Data on socio-economic position (SEP), place of residence (urban, semi-urban and rural), age and test center were also collected.

Results:

From the period 1969–1974 to 2000–2005, the prevalence of moderate obesity almost quintupled (0.8–3.8%; P<0.0001), while morbid obesity increased 10-fold (0.1–1.3%; P<0.0001). The composition of the obese category changed from 12.9 to 25.1% morbidly obese during the same time, corresponding to an annual growth in the odds of 2.8% (CI_95% 2.5–3.1%) per year within the obese category. Compared to 1969–1974, the odds ratios of obesity and morbid obesity, respectively, were 1.6 (1.6–1.7) and 1.9 (1.7–2.2) in 1980–1984, 2.8 (2.7–2.9) and 4.0 (3.5–4.5) in 1990–1994, and 6.0 (5.7–6.3) and 11.4 (10.1–12.9) in 2000–2005, after adjustment for SEP, urban/rural place of residence, age and test center. Extrapolation of the growth rate during the observation period resulted in an estimated 4% morbidly obese in 2020.

Conclusion:

Morbid obesity increased faster than moderate obesity during the last 35 years. As the health risks and costs of obesity-related morbidity increase disproportionately in the morbidly obese, it is important to assess morbid obesity in prevalence studies, and distinguish the morbidly from the moderately obese in cost analyses.