Recovering alcoholics always hope they won't fall off the wagon, but researchers say they have now found a way to predict if that plunge will occur, and how bad the bender will be.

Observers at the University of British Columbia watched the body language of problem drinkers during two videotaped interviews and found newly sober drinkers who showed signs of shame were much more likely to hit the bottle again.

The study is the first to link physical signs of shame, such as slumped shoulders or a narrow chest, to predictions of relapse over the next three to 11 months in people who struggle with substance abuse.

University of BC psychology Prof. Jessica Tracy said the amount of shame displayed is also directly tied to the number of drinks an alcoholic will have on that first binge after giving up sobriety.

Forty-six drinkers recruited from Alcoholics Anonymous meetings completed questionnaires about their physical and mental health. Tracy and a team researchers also assessed their body language in interviews, videotaped four months apart.

Study co-author Dan Rangles said participants who displayed a stronger response in the second interview had consumed more drinks.

"On average they consumed an additional 10.6 drinks between the four months," he said of the study to be published this week by the Association for Psychological Science journal Clinical Psychological Science.

Participants were asked to respond to the question: "Describe the last time you drank and how you felt about it."

Researchers analyzed the first 10 seconds of their response, mostly because people would express their strongest emotional reactions immediately after being asked the question, Randles said.

The study found that unconscious physical mannerisms are a powerful sign of future relapse, while written expressions of shame offer almost no clues because people may repress painful behaviour.