Effect of smoking on the paradox of high waist-to-hip ratio and low body mass index

Abstract

Objective: Research on diabetes mellitus (DM) indicates that people with a low body mass index (BMI) but a high waist-to-hip ratio (WHR) are in a particularly high-risk group. The purpose of this study was to investigate the prevalence of and the effect of smoking on this paradoxical relationship.

Research Methods and Procedures: Our study sample consisted of 3450 men and 4250 women who had participated in the Korean Nationwide Health Examination Survey. We divided the study sample into tertiles (low, medium, and high), according to the level of WHR and of BMI, which yielded nine different combinations. Individuals exhibiting so-called paradox A had the highest WHR and the lowest BMI.

Results: The prevalence of paradox A was 4.7% for men and 3.8% for women. The overall agreement of WHR and BMI groups was poor [for men: κ = 0.31 and 95% confidence interval (CI) = 0.29 to 0.34; for women: κ = 0.39 and 95% CI = 0.37 to 0.42 for women]. The odds ratios for subjects having paradox A were estimated using a logistic regression model after adjusting for age, age2, height, education, smoking, use of alcohol, and exercise. The risk for paradox A among current smokers was 2.1-fold (95% CI, 1.5 to 3.0) higher for men and 2.5-fold (95% CI, 1.6 to 3.9) higher for women than for nonsmokers, after adjusting for age and covariates.

Discussion: Cigarette smoking may increase the risk of paradox A. The findings of this study should be crossvalidated to different populations.