Alcohol drinking in one's thirties and forties is associated with body mass index in men, but not in women: A longitudinal analysis of the 1970 British Cohort Study

Our objective was to investigate longitudinal associations between alcohol drinking and body mass index (BMI). Alcohol drinking (exposure), BMI (outcome), smoking habit, occupation, longstanding illness, and leisure time physical activity (potential confounders) were assessed at ages 30, 34, 42, and 46 in the 1970 British Birth Cohort Study. Multilevel models were used to cope with the problem of correlated observations. There were 15,708 observations in 5931 men and 14,077 observations in 5656 women. Drinking was associated with BMI in men. According to the regression coefficients, BMI was expected to increase by 0.36 (95% confidence interval: 0.11, 0.60) kg/m² per year in men who drank once a week and by 0.40 (0.14, 0.15) kg/m² per year in men who drank most days. In ten years, BMI was expected to increase by 5.4 kg/m² in men who drank and by 2.9 kg/m² in men who drank and were physically active. Drinking was not associated with BMI in women. Rather, BMI was expected to increase by 0.25 (0.07, 0.43) kg/m² per year in women who were former smokers. In ten years, BMI was expected to increase by 4.3 kg/m² in women who were former smokers and by 0.8 kg/m² in women who were former smokers and who were physically active. Associations between drinking and BMI were similar after further adjustment for problematic drinking and diet. These longitudinal data suggest that drinking is associated with BMI in men and that drinking is not associated with BMI in women independent of other lifestyle risk factors.