What counts as 'binge drinking'? What about 'high-intensity drinking'?

During the festive season and other times of celebration, alcohol often flows freely. But how much is too much?

In short, what counts as "binge drinking," and what are the potential health effects?

Most people understand binge drinking as "drinking to get drunk," said Dr. Ryan Marino, a toxicologist and associate professor at Case Western Reserve University. But the National Institute on Alcohol Abuse and Alcoholism (NIAAA) offers a more precise definition.

Binge drinking refers to when a person consumes enough alcohol within about two hours to raise their blood-alcohol concentration (BAC) to 0.08% or higher. That's at least 0.08 grams of alcohol per deciliter of blood, and for average adults, it's about four or more drinks for women and five or more drinks for men. In the U.S., a standard drink contains 0.6 ounces (14 grams) of pure alcohol; that translates to about 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of distilled spirits.

The binge-drinking threshold is lower for women because their bodies generally have more fat and less water than men of the same weight. Because alcohol dissolves in water, not in fat, women therefore reach a higher BAC than men after drinking the same amount.

Related: What does alcohol do to the body?

Notably, there's a behavior that's even more extreme than binge drinking, known as high-intensity drinking. The NIAAA defines this as drinking at levels two or more times the thresholds for binge drinking — so 10 drinks or more for men, or eight or more for women, within about two hours.

What are the health risks of binge drinking?

In the short term, since alcohol slows brain activity, a person's reflexes after binge drinking are slower than normal, which can lead to accidents such as falls, drownings and car crashes. This suppressed brain activity also makes people more likely to engage in risky behaviors, such as unsafe sexual activity or violence, said Sarah Church, a psychologist and CEO of Wholeview Wellness, an addiction treatment center in New York City.

Drinking too much alcohol in a sitting impairs the hippocampus, a brain area critical for forming memories. This can result in blackouts, preventing a person from recalling what happened while they were intoxicated.

When alcohol levels in the bloodstream become excessively high, areas of the brain responsible for vital functions — such as breathing, heart rate and alertness — also begin to shut down. This is called alcohol poisoning, and it can lead to vomiting, seizures, coma or even death.

Health effects of repetitive binge drinking

A single episode of binge drinking can cause these immediate effects, and likely a hangover the next morning. Repeated binge drinking can have severe long-term effects on both physical and mental health.

It's the liver's job to break down alcohol, so if you drink more alcohol than the organ can process, it can become badly damaged, leading to liver disease. Frequent heavy drinking also affects the heart. Excess alcohol consumption is linked to high blood pressure, and over time, this strains the heart and can lead to cardiovascular disease, increasing the risk of heart attack and stroke.

Long-term heavy alcohol use also damages nerves, sometimes leading to "alcoholic neuropathy." Symptoms include numbness, painful sensations in the arms and legs, and difficulty walking.

There's also sufficient evidence to link heavy alcohol use to higher rates of various cancers. "The rate of cancer of the esophagus, stomach, pancreas, [and] liver is elevated in people who repeatedly drink large amounts of alcohol," said Linnea Axman, the associate dean at the University of Phoenix College of Nursing.

It also disrupts gut health. The gut is home to a large community of bacteria, the "gut microbiome," and "drinking excessive amounts of alcohol can lead to gut dysbiosis, an imbalance of the gut microbiome," said Trista Best, a registered dietitian. That means certain types of gut bacteria become too abundant, while others decline, with negative effects.

Alcohol can simultaneously weaken the gut lining, making it more permeable, which can allow harmful substances to enter your bloodstream, Best added. This can contribute to chronic gut inflammation.

Binge drinking increases the risk of developing an alcohol use disorder (AUD), a disease that causes craving for alcohol, loss of control when drinking and a negative emotional state when not drinking. Not everyone who binge drinks has an AUD, but their increased risk is significant.

High-intensity drinking amplifies all of these risks of binge drinking, said Dr. Rostislav Ignatov, a psychiatrist and chief medical officer at The Haven Detox, a group of addiction treatment centers. In the short term, severe alcohol poisoning or organ shutdown are more likely with high-intensity drinking than with binge drinking. Over the long term, the former accelerates the risk of developing organ damage and cancer typically tied to binge drinking, he said.

"Anyone who is concerned about their drinking should speak to a health care professional to see what treatment options are right for them," said Peter Vernig, a psychologist and vice president of mental health services at Recovery Centers of America.

Treatment options range from inpatient programs, in which you stay at a facility, to outpatient therapy groups and counseling. There are also prescription medications, such as naltrexone, that help to reduce alcohol cravings and dependence. "The most important thing to do is to reach out and start the conversation," Vernig emphasized.