This is the weird reason you drink more wine at restaurants

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The right wine can be the perfect cherry on top for a great evening out at a restaurant. Of course, we’ve all ended up drinking maybe a bit more than we originally intended as certain nights out unfold. If you’ve ever looked back on a meal and wondered how you ended up drinking as much wine as you did, according to researchers at the University of Cambridge, there may be an unlikely culprit to blame: your glass.

Their new study finds that the size of the glasses used to serve wine in restaurants often influences the number of wine diners end up purchasing. The bigger the glass, the more likely a patron is to order a second helping.

For whatever reason, this same effect didn’t seem to translate to bars. Apparently there’s just something about a big wine glass within a restaurant setting that makes us all just a little bit more thirsty. 

Interestingly, the average wine glass used in a modern restaurant these days is quite bigger than what would have been used in say, 1980. In fact, the average wine glass used in England just about doubled in size around 1990. Coincidentally, or perhaps not, the amount of wine being consumed across the pond has quadrupled since then.

Alcohol is a layered topic in general. It’s promoted all over the world as the key to a good time, and while millions indulge each and every weekend, there’s no denying alcohol doesn’t do our bodies any favors. And that’s not even mentioning it’s highly addictive nature and the number of lives alcoholism has ruined. 

So while these findings may sound humorous and anecdotal at first, they could help someone in need reduce their alcohol intake, even if ever so slightly.

It would have been quite difficult for the research team to find accurate data on just how much wine people were drinking at restaurants precisely, so they instead opted to use data on wine sold at restaurants in the Cambridge area. They analyzed a comprehensive dataset comprised of previous studies performed on Cambridge restaurants between 2015 and 2018. They used 300 ml (just over 10 fluid ounces) glasses as a reference point to compare consumption fluctuations.

They discovered a clear pattern; when restaurants increased their glass sizes to 370 ml, their sales increased by 7.3%. Conversely, restaurants that reduced their typical wine glass size to 250 ml saw their wine sales drop by 9.6%.

“Pouring wine from a bottle or a carafe, as happens for most wine sold in restaurants, allows people to pour more than a standard serving size, and this effect may increase with the size of the glass and the bottle,” explains first study author Dr. Mark Pilling in a press release. “If these larger portions are still perceived to be ‘a glass’, then we would expect people to buy and consume more wine with larger glasses.”

It’s important to note, however, that when glass sizes especially large (450 ml) were considered, the researchers saw no sales increases in comparison to 300 ml glasses.

“As glass sizes of 300ml and 350ml are commonly used in restaurants and bars, drinkers may not have noticed the difference and still assumed they were pouring a standard serving. When smaller glass sizes of 250ml are available, they may also appear similar to 300ml glasses but result in a smaller amount of wine being poured,” Dr. Pilling explains. “In contrast, very large glasses, such as the 450ml glasses, are more obviously larger, so drinkers may have taken conscious measures to reduce how much they drink, such as drinking more slowly or pouring with greater caution.”

Besides just wine glasses, the study’s authors also found that temperatures and days of the week can influence our wine habits as well. People tend to drink less wine when it’s hot out, and predictably, drink more wine over the weekend.

“We all like to think we’re immune to subtle influences on our behaviour – like the size of a wine glass – but research like this clearly shows we’re not.” comments Professor Ashley Adamson, Director of the NIHR School of Public Health Research. “This important work helps us understand how the small, everyday details of our lives affect our behaviours and so our health. Evidence like this can shape policies that would make it easier for everyone to be a bit healthier without even having to think about it.”

No one wants to believe that they aren’t 100% in control of their own decisions and actions, but studies like this just go to show how many contributing environmental factors may be influencing our decisions on an unconscious level.

The full study can be found here, published in Addiction.