Different associations between body composition and alcohol when assessed by exposure frequency or by quantitative estimates of consumption.

Background: Alcohol intake is widely assumed to contribute to excess body fatness, especially among young men; however, the evidence is inconsistent. We have addressed this research question by investigating associations between reported alcohol consumption and body composition from large representative national surveys in a high alcohol-consuming country with a high obesity prevalence.

Methods: The present study comprised a secondary analysis of combined cross-sectional nationally representative Scottish Health Surveys (1995-2010). Reported alcohol-drinking frequency was divided into five groups: from 'nonfrequent drinking' (reference) to daily/'almost every day' among 35 837 representative adults [mean (SD) age: 42.7 (12.7) years (range 18-64 years)]. Quantitative alcohol consumption was categorised into seven groups: from '1-7 to ≥50 10 g units per week'. Regression models against measured body mass index (BMI) and waist circumference (WC) were adjusted for age, physical activity, income, smoking, deprivation category and economic status.

Results: Among alcohol-consuming men, heavier drinking (21-28 units per week) was associated with a higher BMI by +1.4 kg m [95% confidence interval (CI) = 1.38-1.43] and higher WC by +3.4 cm (95% CI = 3.2-3.6) than drinking 1-7 units per week. However, those who reported daily drinking frequency were associated with a lower BMI by -2.45 kg m (95% CI = -2.4 to -2.5) and lower WC by -3.7 cm (95% CI = -3.3 to -4.0) than those who reported less-frequent drinking. Similar associations were found for women. Most of these associations were restricted to subjects aged >30 years. Unexplained variances in BMI and WC are large.

Conclusions: Quantitative alcohol consumption and frequency of consumption were positively and inversely associated, respectively, with both BMI and WC among alcohol-consuming adults. Surveys are needed that evaluate both the quantity and frequency of consumption. The lowest BMI and WC were associated with a 'Mediterranean' drinking style (i.e. relatively little, but more frequently).