Aims: We tested whether reducing the standard serving size of alcoholic beverages would reduce voluntary alcohol consumption in a laboratory (study 1) and a real-world drinking environment (study 2). Additionally, we modelled the potential public health benefit of reducing the standard serving size of on-trade alcoholic beverages in the UK.Design: Studies 1 and 2 were cluster-randomised experiments. In study 1, participants were randomly assigned to receive standard or reduced serving sizes (by 25%) of alcohol during a laboratory drinking session. In study 2, customers at a bar were served alcohol in either standard or reduced serving sizes (by 28.6% – 33.3%). Finally, we used the Sheffield Alcohol Policy Model to estimate the number of deaths and hospital admissions that would be averted per year in the UK if a policy that reduces alcohol serving sizes in the on-trade was introduced.Setting: A semi-naturalistic laboratory (study 1), a bar in Liverpool, UK (study 2).Participants: Students and university staff members (study 1: N = 114, mean age 24.8 years, 74.6% female), residents from local community (study 2: N = 164, mean age 34.9 years, 57.3% female).Measurements: Outcome measures were units of alcohol consumed within one hour (study 1) and up to three hours (study 2). Serving size condition was the primary predictor. Findings: In study 1, a 25% reduction in alcohol serving size led to a 20.7% - 22.3% reduction in alcohol consumption. In study 2, a 28.6% - 33.3% reduction in alcohol serving size led to a 32.4% - 39.6% reduction in alcohol consumption. Modelling results indicated that decreasing the serving size of on-trade alcoholic beverages by 25% could reduce the number of alcohol-related hospital admissions and deaths per year in the UK by 4.4% - 10.5% and 5.6% - 13.2%, respectively. Conclusions: Reducing the serving size of alcoholic beverages leads to a reduction in alcohol consumption within a single drinking occasion. Reducing the standard serving sizes of alcoholic beverages may reduce alcohol consumption and alcohol-related harm at the population level.
Inaccuracies in survey reporting of alcohol consumption