Determinants of geographical variations in body mass index (BMI) and obesity in Spain

Abstract

OBJECTIVE:To identify the factors associated with geographic variations in Body Mass Index (BMI) and obesity in Spain.

DESIGN:Cross-sectional, ecological analysis using data on illiteracy rate (per 1000 population), energy intake (kcal//person/-4/d), sedentary population (%), smoking population (%), alcohol consumption (g/person/d), and percentage of population aged 65 y or over, for Spain’s 50 provinces.

SUBJECTS:Non-institutionalized population aged 16 y or over.

MEASUREMENTS:Median BMI and percentage of population with obesity, defined as BMI>30 kg/m².

RESULTS:There was a clear geographical pattern, with some areas in the south and north-west of the country registering the highest BMI and prevalence of obesity and a north–south pattern on illiteracy per 1000 population. Multivariate regression analysis showed that illiteracy, sedentary lifestyle and energy intake explain 35% and 14% of the variation in BMI and obesity, respectively. Illiteracy proved to be the variable most associated with both BMI (regression coefficient (β=0.01; P=0.005) and obesity (β0.05; P=0.013). Sedentary lifestyle showed a statistically significant relationship with BMI (β=0.01; P=0.03), but not with obesity (β=0.03; P=0.581). Energy intake exhibited a relationship with BMI (β<0.01 P=0.03) that lost statistical significance when adjusted for age.

CONCLUSION: Geographical variations in BMI in Spain are partly explained by illiteracy, sedentary lifestyle and, to a lesser extent, energy intake, whereas regional variations in obesity are related only to the educational level of the population.