If you're guilty of having one too many on a regular basis, the size of your wine glass may be to blame.
New research has found that buying wine in larger glasses may encourage us to drink more, even when the amount of wine in each glass remains the same.
The study, from the University of Cambridge, found that people were more likely to order additional glasses of wine at a bar when they were presented with a large glass (370ml) instead of a standard glass (300ml).
They believe it may be because large glasses encourage us to drink faster.
In theory, this means you may be able to trick yourself into cutting back on booze by rethinking your glass size.
To examine whether glass size affects overall alcohol consumption, the Cambridge research team, together with Professor Marcus Munafo from the University of Bristol, carried out a study in a bar in Cambridge from mid-March to early July 2015.
The establishment, called The Pint Shop, has separate bar and restaurant areas, both selling food and drink.
During the study, wine (in 125ml or 175ml servings) could be purchased by the glass, which was usually a standard 300ml size.
Over the course of a 16-week period, the owners of the establishment changed the size of the wine glasses at fortnightly intervals, alternating between the standard (300ml) glass size, and larger (370ml) and smaller (250 ml) glasses.
The researchers found that the volume of wine purchased daily was 9.4% higher when sold in larger glasses compared to standard-sized glasses.
This effect was mainly driven by sales in the bar area, which saw an increase in sales of 14.4%, compared to an 8.2% increase in sales in the restaurant.
The findings were inconclusive as to whether sales were different with smaller compared to standard-sized glasses.
"We found that increasing the size of wine glasses, even without increasing the amount of wine, leads people to drink more,” Dr Rachel Pechey from the Behaviour and Health Research Unit at Cambridge commented.
"It’s not obvious why this should be the case, but one reason may be that larger glasses change our perceptions of the amount of wine, leading us to drink faster and order more. But it’s interesting that we didn’t see the opposite effect when we switched to smaller wine glasses."
Professor Theresa Marteau, director of the unit, added: “This suggests that avoiding the use of larger wine glasses could reduce the amount that people drink.
"We need more research to confirm this effect, but if it is the case, then we will need to think how this might be implemented.
"For example, could it be an alcohol licensing requirements that all wine glasses have to be below a certain size?"
The researchers noted the study could be useful as alcohol consumption is currently one of the leading risk factors for disease and has been linked to conditions such as Type 2 diabetes, cancer and liver disease.
The study, which was funded by the Department of Health, is published in full in the journal BMC Public Health.
