Based on the findings, the investigators argue that lower limits for “safe” alcohol consumption in heavier people may be necessary.

Deaths from liver disease have risen in certain parts of the world, and alcohol consumption patterns don’t completely explain this observation, Dr. Carole L. Hart of the University of Glasgow and her colleagues write in the British Medical Journal.

Given that obesity is on the rise, and that excess weight has been linked to disease, Hart and her team investigated whether alcohol consumption and being overweight act together to increase the risk of liver disease.

The researchers looked at two studies including a total of 9,559 men from Scotland. The first study enrolled people between 1965 and 1968, and the second enrolled people in 1970 and 1973. All were followed through the end of 2007.

During that time, 80 men died of liver disease, while 146 died from causes including liver disease. Within the second study, the researchers identified 196 men with liver disease through cancer registries, deaths, or hospital admission.

The men who downed 15 drinks a week or more had triple the risk of liver disease if they were normal-weight or underweight compared to non-drinking men in the same weight range. In contrast, overweight men who drank this much were seven times more likely to have liver disease than slimmer non-drinkers.

Risk was increased 19-fold for heavy drinking, obese men compared to thin teetotalers.

Obese men who drank from one to 14 drinks each week were about five times more likely to have liver disease compared to normal- or underweight non-drinkers.

There are several possible mechanisms through which excess weight could contribute to alcohol-related liver disease, and vice-versa, the researchers say; obesity can promote inflammation and fat accumulation in the liver - as does excessive drinking - while this type of liver damage, known as steatohepatitis, can also contribute to obesity by boosting insulin resistance.

“New perspectives on the risk of liver disease may need to be considered for people who are overweight and consume alcohol,” they conclude. Lower “safe limits” of alcohol consumption may need to be defined in overweight and obese individuals, they add.

SOURCE: BMJ, online March 22, 2010.