Binge drinking once a week raises the risk of health problems almost five times – even if you are teetotal the rest of the time, according to new research.
Moderate drinkers who consume their units in one go are far more likely to develop health issues than those who get through the same amount, but spread it out.
The NHS advises a weekly limit of 14 units – equivalent to six pints of beer or 10 small glasses of wine.
Lead author Professor Charles Holahan, a psychologist at Texas University in Austin, says: "What this means is an individual whose total consumption is seven drinks on Saturday night presents a greater risk profile than someone whose total consumption is a daily drink with dinner – even though their average drinking level is the same."
Binge drinking is increasing in the UK – partly because so many people are working from home.
YouGov surveys show the trend is endangering almost one in five adults in England alone – equating to eight million.
The NHS defines binge drinking as “drinking lots of alcohol in a short space of time or drinking to get drunk”.
Because everybody is different, it is not easy to say exactly how many units in one session count as binge drinking.
The definition used by the Office for National Statistics for binge drinking is having over eight units in a single session for men and over six units for women.
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Prof Holahan and colleagues analysed data on 1,229 over-30s across the US who were tracked for nearly a decade.
They found people with a pattern of binge drinking were almost five times as likely to experience multiple alcohol problems.
Their risk of suffering more related-issues also doubled over the next nine years.
Co-author Prof Rudolf Moos, of Stanford University in California, adds: "In both scientific and media discussions of moderate drinking, the pattern of drinking is generally overlooked.
"This leaves many drinkers mistakenly assuming a moderate average level of consumption is safe – regardless of drinking pattern."
Previous studies have tended to focus on teenagers and students but most binge drinking occurs among older individuals – with prevalence rising.
Research on adult alcohol consumption and its effects usually looks only on a person's average level, which masks heavy sessions.
As a result the impact among low and moderate drinkers has not been well understood – until now.
Participants were members of the Midlife Development in the US study carried out in two waves, shedding light on the long-term effects of drinking patterns.
The investigators said they were surprised by their findings. Most cases of binge drinking and multiple alcohol problems occurred among moderate average drinkers.
The study in the American Journal of Preventive Medicine supports a growing recognition that binge drinking among adults is a public health concern.
Prof Holahan and colleagues called for increased efforts to address it. "Much binge drinking among adults escapes public health scrutiny because it occurs among individuals who drink at a moderate average level," he says.
"These findings point to a need for alcohol interventions targeting moderate average level drinkers in addition to conventional strategies focusing on the higher risk, but smaller, population of habitually high-level drinkers."
An earlier study found binge drinking doubled the risk of premature death in moderate drinkers. The same team followed hundreds of 55 to 65-year-olds for up to 20 years.
Additional reporting SWNS