Objective: Some recent studies have shown stablity or declining trends in obesity while others still report increasing trends. The present study aimed to investigate the trends of obesity and abdominal obesity in Tehranian adults during a median follow-up of 10 years.

Design: Prospective cohort study.

Setting: Community-based data collection from the Tehran Lipid and Glucose Study (TLGS).

Subjects: Participants from four phases of the TLGS from 1999 to 2011 (n 10,368), aged ≥20 years.

Results: The crude prevalence of obesity and abdominal obesity increased from 23·1% and 47·9% at baseline to 34·1% and 71·1% at the end of follow-up, respectively. Generalized estimating equation (GEE) models were used to analyse the correlated data and calculate the relative risks (RR). Risks of obesity and abdominal obesity increased over the whole study period for men (RR=1·62; 95% CI 1·49, 1·76 and RR=1·46; 95% CI 1·41, 1·52, respectively) and women (RR=1·24; 95% CI 1·19, 1·29 and RR=1·22; 95% CI 1·18, 1·27, respectively). These rising trends were observed in all subgroups regardless of age, marital status and educational level.

Conclusions: Trends of obesity and abdominal obesity are increasing in Tehranian adults during a decade of follow-up in both genders and in all study subgroups. These results underscore the still growing obesity epidemic in the capital of Iran, calling for urgent action to educate people in lifestyle modifications and the need for effective preventive and educational strategies on obesity.