There’s a condition often suffered by wine drinkers, one that I always attributed to the fact that my skeleton is made of Osmium, wherein your hand becomes so heavy that before you know it, there’s quite a large serving of wine in the glass. The only way to resolve that situation is of course, to drink it. But it turns out not everyone has dense hand bones, says a new study, wine drinkers just tend to be the over-serving sort when pouring for themselves.

Researchers at Iowa State University and Cornell University found that when people drink wine, a lot of them don’t even realize how much they’re consuming because of variables like the size, shape or color of the glass, reports the Des Moines Register. It all becomes very confusing until oops, half the bottle is gone, it’s midnight and infomercials are wildly entertaining.

A standard serving size is five ounces, says National Institute on Alcohol Abuse and Alcoholism, but depending on what kind of wine you’re pouring into whichever vessel you’ve picked often makes it an overpoured situation.

Researchers found that participants poured 12% more wine into a wide glass than a narrow one because we tend to judge volume by height, not width, say researchers. Participants also poured 12% more into glasses they held in their hands, as opposed to a glass sitting on a table.

White wine drinkers are even more heavy-handed than their red wine counterparts, over-pouring white wine into clear glasses by 10%. Red wine was more likely to be served closer to a normal serving size.

Lest you think you’ll change your heavy-handed ways now that you know what you’re doing, well, you probably won’t. Researchers told participants when they were over-pouring, but they still did it, said Laura Smarandescu, an Iowa State marketing professor and co-author of the study.

“A lot of times consumers don’t know how much they drink. Especially when they buy a bottle of wine, it’s less clear how much each person consumes,” she said. “And when people pour on top of wine still in a glass, that bias increases by a lot.”

Ah yes, the old “top me up while you’ve got it in your hand” trick. I know it well.

If you don’t want to over indulge, stock up on narrower wine glasses, red wine and make sure your glass is empty and sitting on the table before your next pour. Or stay just the way you are and enjoy those infomercials.

Study: Wine drinkers often don’t realize how much they consume [Des Moines Register]

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