A British survey showed that the average man and woman underreported their weekly drinking consumption by as much as 60 percent.
The study, which was published in the European Journal of Public Health on Feb. 26, compared reported statistics from how much people said they drank to the actual amount of alcohol purchased in England.
"Currently we don't know who consumes almost half of all the alcohol sold in England. This study was conducted to show what alcohol consumption would look like when all of what is sold is accounted for, if everyone underreported equally," lead author Sadie Boniface, a PhD student in the University of London's department of epidemiology and public health, said in a press release. "The results are putative, but they show that this gap between what is seen in the surveys and sales potentially has enormous implications for public health in England."
Currently, the Royal College of Physicians recommends up to 21 units of alcohol for men and 14 units of alcohol for women a week, and the U.K. chief medical officer advises not to go over four units per day for men and three for women. In the U.S., the Centers for Disease Control and Prevention defines binge drinking as 5 more drinks on one occasion for men or 4 or more at one event for women.
The researchers used data from surveys previously taken by 22,100 representative adults to determine the level of drinking people were reporting. They then looked at the sales records of the amount of alcohol sold at that time and divided it by the number of drinkers in England. Comparing the two figures, they were able to estimate how much people were underreporting their drinking (assuming that everyone underestimated at the same rate).
Overall, alcohol sales figures were 40 to 60 percent higher than the the amount of drinking reported in the surveys. The researchers discovered that men underestimated their drinking by 15 percent on average and women did so by 11 percent. This means that 44 percent and 31 percent of men and women respectively drink more than British guidelines suggest. Adjusted figures show that 75 percent of men (19 percent above what the surveys reported) and 80 percent of women (26 percent above what the surveys said) go above the daily recommended intake.
One survey, the Health Survey for England, showed that 32 percent of men and 28 percent of women have a binge-drinking session weekly. After sales were calculated, the figure should be about 52 percent or men and 56 percent for women.
The study also shows that when the sales figures are used, about half of male and women drinkers are "binge drinkers," which in the UK means that hey drink eight or more units of alcohol at one event for men and six or more for women. Binge drinking rose the most for women, those with higher incomes and those living in southern England.
Boniface added to the Telegraph that wine drinkers were less likely to lie about their drinking habits compared to those who drank beer and spirits. She believes that most people participate in "selective reporting," meaning that they underestimate how much they are drinking because they forget or don't know how big or strong their beverages are.
"(The study) contradicts the claims of the alcohol industry that only a small minority drink too much, and is yet more evidence of the need for strong government action, including a minimum unit price for alcohol," Richard Thompson, president of the Royal College of Physicians, which represents hospital doctors, told the Guardian.
The U.K. Department of Health said that they will factor in the study when making their recommendations about new alcohol legislation.
"We already know people underestimate what they drink and many drink too much," they told the BBC in a statement. "That's why we work to help people make healthier decisions, including the recent Change For Life campaign to help them track consumption and understand the impact on their health.... We're also tackling excessive drinking through our proposed minimum unit price at 45p per unit, tougher licensing laws, more GP risk assessments, better access to specialist nurses and more specialized treatment."
However, Aileen Keyes from the Wine and Spirits Trade Association told the Telegraph that the report didn't use real information. She pointed out that researchers based their model on 2008 data to create a "hypothetical scenario." It also didn't factor in that U.K. Treasury data showed that alcohol consumption has dropped by 13 percent.