General obesity and central adiposity in a representative sample of Tehranian adults: prevalence and determinants

To determine the prevalence and associations of general and central obesity in adults residing in district 13 of Tehran and to examine the associations of obesity with certain factors.

Population-based cross sectional study.

Tehran, the capital of Iran.

A total of 9984 subjects (4164 men and 5820 women) aged 20-70 years.

Demographic data were collected and anthropometric indices including weight, height, and waist and hip circumference were measured, according to standard protocols. Dietary intake was assessed by means of two 24-hour dietary recall forms. To determine the prevalence and association of general and central obesity, the suggested cut-off for Tehranian people, adjusted for their age group, was used. A body mass index (BMI) of > or =24 for men and > or =25 for women was used to determine the characteristic of obesity. Central obesity was determined as a waist-hip ratio (WHR) of > 0.86 for men and WHR > or = 0.78 for women. To determine the associations between general and central obesity and other factors, logistic regression was used.

The means of BMI, waist circumference (WC), and WHR were 25.8 +/- 4.1 kg/m2, 88.3 +/- 11.4 cm, and 0.91 +/- 0.07 in men and 27.3 +/- 5.4 kg/m2, 87.5 +/- 12.9 cm, and 0.83 +/- 0.08 in women, respectively. Obesity and central obesity were higher in women than in men; 67% vs. 29% for obesity and 93% vs. 74.1% for central obesity, respectively. Illiteracy (OR = 1.65; 95% CI = 1.13-2.41 in men; OR = 1.87, 95% CI = 1.59-2.21 in women), marriage (OR = 3.84, 95% CI = 3.63-4.29 in men; OR = 3.20, 95% CI = 3.63-4.19 in women), and very low physical activity (OR = 1.35, 95% CI = 1.09-1.53 in men; OR = 1.39, 95% CI = 1.10-1.76 in women) were factors associated with obesity. The risk of being centrally obese for men in the fourth quartile of legumes intake was lower than men in other quartiles (p < 0.05). Women in the first quartile of dairy consumption had the highest risk of being generally and centrally obese (OR = 2.16, 95% CI = 1.72-2.48 for general obesity and OR = 3.01, 95% CI = 2.36-3.67 for central obesity). The risk of obesity for women in the fourth quartile of energy and saturated fatty acid consumption was higher than for those in the first quartile (OR = 2.69, 95% CI = 2.39-3.11 for energy and OR = 1.36, 95% CI= 1.10-1.64 for saturated fatty acids). The risk of being centrally obese was higher for women in the first quartile of protein intake compared with women in the fourth quartile (OR = 1.71, 95% CI = 1.02-2.32).

The results from this national population-based study in Iran show high prevalence of obesity in Tehranian adults. The strong associations between obesity and certain life style factors confirm the necessity of multifactorial intervention.