Over the past several years, there has been a rise in alcohol-related deaths and a steady wave of news about the health risks of drinking. Calls for people to drink only in moderation have become more urgent. But what exactly does that mean?

“Tongue in cheek, people have defined it as not drinking more than your doctor,” said Tim Stockwell, a scientist at the Canadian Institute for Substance Use Research in Victoria, British Columbia.

More officially, in the United States, moderate drinking is defined as one drink or less per day for women and two drinks or less per day for men. But other countries define moderate drinking, also called low-risk drinking, differently, and recent research around alcohol’s health harms has raised questions about current guidelines.

How are the guidelines formulated?

Experts used to think that low or moderate amounts of alcohol were good for you. That assumption was based on research showing that people who drank in moderation lived longer than those who abstained or drank excessively. The longevity benefit disappeared around two drinks a day for women and three drinks a day for men, Stockwell said.

But many researchers now think that those conclusions were based on data analyses that had “all kinds of methodological problems”, said Elizabeth Mayer-Davis, a professor of nutrition and medicine at the University of North Carolina, Chapel Hill, US.

For example, one issue was that many people who abstained from alcohol did so because they had existing health problems, while people who drank moderately were more likely to have healthy lifestyle habits. It created “really what was an illusion of health benefits with low to moderate amounts of drinking”, Mayer-Davis said.

A new method for establishing risk looks just at deaths from conditions directly related to alcohol, such as liver cirrhosis, alcohol poisoning, pancreatitis and certain types of cancer.“It’s much less biased and confounding if you just focus on alcohol-caused conditions,” Stockwell said.

Using this method, experts have found that low-risk drinking entails less alcohol than what many nations, including the US, currently advise. But the precise level at which alcohol consumption starts to harm health, and what is considered an acceptable level of risk, is still up for debate.

A few countries have adjusted their recommendations. Australia and France now advise that both sexes consume no more than 10 drinks per week. Canada’s latest guidelines, which Stockwell advised on, are more stringent: low-risk drinking is defined as no more than two drinks total per week, regardless of sex.

For the most recent American guidelines, issued in 2020, an advisory committee led by Mayer-Davis recommended that men and women consume no more than one drink per day. That guidance incorporated the latest research that “there was no amount of alcohol that benefited health”, Mayer-Davis said. “But we’re not going to go so far as to say everybody needs to stop drinking, because that’s not realistic,” she added.

The US department of agriculture and the department of health and human services, which set the official guidelines, rejected the committee’s advice. When asked why, a representative for the USDA stated in an email that “the emerging evidence noted in the committee’s report does not reflect the preponderance of evidence at this time”. The next set of dietary guidelines are scheduled tobe released in 2025; it remains to be seen if, and how much, they will change.

Should men and women have different limits?

Despite the trend to establish one limit for both sexes, some experts say that having separate guidelines makes sense.

That’s because it takes less alcohol to negatively affect women’s health than it does men’s, including a greater risk of alcohol-related liver damage, heart disease and certain types of cancer, said Aaron White, the senior scientific adviser to the director at the National Institute on Alcohol Abuse and Alcoholism in the US.

Some of that greater risk may stem from size differences. But even if “a woman and a man who are the same age and same weight drink the exact same amount of alcohol, the woman will have a higher blood alcohol concentration than the man”, said Sherry McKee, the director of the Yale Program for Sex Differences in Alcohol Use Disorder in the US.

One potential reason is that alcohol does not enter fat tissue, and women tend to have a higher proportion of fat than men. That means there’s less space for alcohol to distribute throughout the body, resulting in higher concentrations. Women also don’t metabolise alcohol as easily as men do, so more alcohol stays in their bodies for longer, which can result in more damage.

The changing and inconsistent recommendations can “frustrate the heck out of the public”, Mayer-Davis said. “But that’s the best we can do, make recommendations based on science with the available literature and the available knowledge.”

While the specifics remain unsettled, there is one thing most experts have come to agree on. “Less is more; less is better,” Stockwell said. “Drink less;live longer.”

New York Times News Service