You’ve probably seen a few headlines about how, contrary to popular belief, drinking alcohol "in moderation" is good for you. And I’m sure you’ve even seen an article or two about resveratrol, the allegedly magical, longevity-boosting antioxidant in wine that should make it totally healthy to drink a couple of glasses of wine a day.
The truth, however, is far more complex. Not all research on alcohol consumption is negative, and there are some surprising biological sex-based differences in how alcohol affects the body. Overall, however, the picture is mostly unfavorable.
Is Alcohol Bad for You?
Alcohol Wreaks Havoc on Your Sleep Schedule
For most people, drinking alcohol in the evening can aid in getting to sleep faster. However, this comes at the cost of reducing sleep quality. In drinkers without alcohol use disorders, alcohol (at least in smaller amounts) disrupts sleep primarily during the second half of the night.
Alcohol affects the type of sleep you get, increasing slow-wave sleep while decreasing REM sleep. In general, slow-wave sleep is associated with physical recovery and REM sleep with mental recovery. (REM sleep is also when most dreaming occurs.) On the surface, this sleep situation clearly sounds like a mixed bag rather than being entirely negative.
Related: 4 Ways to Sleep Deep and Grow Stronger
However, alcohol-aided sleep does not actually seem to lead to any physical benefits. Whether this is due to lack of energy and motivation to exercise the following day, liver damage, or simply because we don’t fully understand what the different types of sleep do for us, is unknown at this time.
One possibility is suggested by electroencephalogram (EEG) studies: While increasing delta-wave (deep) sleep, alcohol also increases the prevalence of higher-energy alpha waves in the frontal areas of the brain during the early stages of sleep. Alpha waves — normally dominant during REM sleep and periods of relaxed wakefulness such as meditation or while reading — that are overly-present during slow-wave sleep may possibly make that sleep less restful. In other words, mere quantity of REM and slow-wave sleep may not be the best way to measure sleep quality.
Note that all of this pertains to before-bed alcohol consumption of people without alcohol use disorders. (The effects in alcoholics are far worse and entirely unequivocal.) Some research even finds that evening alcohol consumption disrupts sleep more in women than in men, while the reason for this is unknown.
Why Pre-Bed Alcohol Diminishes Your Sleep Quality
Alcohol converts to sugar (as well as the toxic metabolite acetaldehyde) when the liver breaks it down, and that subsequent rise in blood sugar may be a major reason for delayed sleep impairment after alcohol intake.
Alcohol's Effect on Hormonal Health
Alcohol, unsurprisingly, is bad for hormonal health. Because men and women have different hormonal pathways, this part of the research has to be divided by biological sex.
In men, heavy alcohol consumption reduces testosterone by several different pathways. First, alcohol is toxic to the Leydig cells that produce testosterone in the testes. It also reduces the production of the luteinizing hormone and follicle-stimulating hormone in the hypothalamus, both of which tell the testes to produce testosterone and sperm, respectively.
And these effects only build up over time. Male alcoholics have worse hormonal function the longer they’ve been drinking excessively. The same is likely true — albeit to a much lesser degree — of those who drink moderate to heavy amounts of alcohol without qualifying as alcoholics.
Finally, alcohol acutely increases the conversion of testosterone to estrogen (a process called aromatization) in the liver. Estrogen reduces the secretion of a gonadotropin-releasing hormone, which tells the hypothalamus to create luteinizing hormone and follicular-stimulating hormone in the brain. (Testosterone does, too, but to a lesser extent.)
Why Acute Testosterone Increases Aren't Automatically Positive
Surprisingly, light alcohol intake of one to three drinks acutely increases testosterone. On the other hand, heavier intake — around four to eight drinks — acutely lowers testosterone levels by around 15-20%. It can take your body 24-48 hours to recover from this sort of one-time binge.
Why do low doses of alcohol increase testosterone? Probably by impairing testosterone breakdown by the liver, which actually isn't good. Higher doses presumably have the opposite effect, by acutely damaging and shutting down testosterone production in the testes.
It's a different story for women, as alcohol intake increases both testosterone and estrogen in women (and in this case, higher doses don’t reverse that relationship). Estrogen helps build up your muscles and joints (though less so than testosterone). This seems surprisingly good, although it doesn’t tell the whole story.
Alcohol Diminishes Gains Made During Training
Alcohol reduces growth hormone production. Growth hormone is anabolic on (or it helps build up) both muscles and connective tissue. And because it’s not a sex hormone, this part should work the same for both men and women.
In men, light drinking post-workout doesn’t seem to measurably reduce exercise recovery, but heavier drinking does. Overall, the acute effects on exercise recovery are surprisingly mild — it’s much more so the chronic effects of alcohol that will affect your physique.
By contrast, women who drink up to six shots of liquor after their workout don’t seem to have adverse effects on recovery. Post-workout consumption of several shots of vodka reduces the main genetic signaling pathway for muscle growth in men, but not in women.
Like the hormonal effects of alcohol, the effects on muscle growth are directly negative for men, but only indirectly and chronically for women.
Alcohol's Effect on General Health and Longevity
Not only is alcohol damaging to the liver, but the main breakdown product of alcohol (other than sugar) is acetaldehyde, which is both liver-toxic and carcinogenic.
And speaking of sugar, alcohol contains 7 calories per gram (more than the 4 in carbs and protein, and less than the 9 in fat). This means that when you drink alcohol, it either displaces healthier foods or simply leads to a caloric surplus. A standard drink — a shot of dry liquor or glass of dry wine — has 14 grams of alcohol. A 12-ounce, 5% alcohol beer has the same amount, plus some carbs. That means that every drink is 98 empty calories displacing food with actual nutrients. (It also means that low-carb beer is kind of a sham.)
The Nutritional Deficiencies You Don't Want or Need
Heavy or chronic alcohol use damages the intestinal lining, impairing nutrient absorption. Alcoholism is associated with a wide variety of nutrient deficiencies, but even moderate drinking puts you at risk of milder versions of these.
Note that because women tend to be smaller and have higher body fat percentages, they suffer more from the calorie content of alcohol and its associated nutritional displacement. For many women, even “light” drinking means consuming the caloric equivalent of an entire meal, and that’s before you start talking about sugary mixed drinks. Plus, alcohol can cause peripheral neuropathy and cardiomyopathy, and, for unclear reasons, women may be more susceptible to these issues.
Is Longevity a Myth?
But what about resveratrol’s incredible longevity benefits? They may very well be real! However, the dosages involved equate to hundreds of milligrams per day in humans. Resveratrol supplements are dosed in the hundreds of milligrams, and often up to one gram.
What does one glass of wine have? Anywhere from .03 to 3 milligrams. In other words, insignificant.
Now, it is true that alcohol intake is positively associated with longevity, and also that wine intake is often associated with better health outcomes than other forms of alcohol. However, these are observational and correlational studies, not experiments. Consider that drinking is often associated with having a good social life, and wine consumption is generally associated with higher social class compared to beer and liquor. Failure to control for these variables makes any such study suspect.
There’s also a tendency towards self-fulfilling prophecy effects in health research: If wine is — hypothetically — widely perceived to be healthier, more health-conscious people will gravitate toward it and away from the alternative. That means that you’d also need to control for all kinds of health behaviors such as nutritional intake and exercise, which studies rarely fully manage to do.
So, How Bad Is Alcohol REALLY?
The truth? It’s mostly bad for you. The reasons for this are varied, and different ones predominate depending on biological sex. Alcohol is bad for sleep, but more so in women. It’s harmful to men’s hormonal health and muscle growth, but surprisingly not for women. It damages the liver and raises the risk of cancer for all.
It’s entirely possible, however, that the biggest problem with alcohol is simply that it’s another source of empty calories. (Beyond all of these other effects, it’s basically sugar, even though it doesn’t taste sweet.) And again, this part is worse for women for the simple reason that they’re generally smaller and have lower basal metabolic rates.
Bearing all of this in mind, some health experts argue that the optimal level of alcohol consumption is zero. While that’s certainly debatable and based on a fair amount of filling in the blanks, what’s not controversial is that alcohol becomes clearly negative beyond 100 grams — or 7 drinks — a week.
In other words, while it’s probably best not to drink at all, light drinking of one to three drinks (once or maybe occasionally twice a week), isn’t hugely damaging. More moderate drinking a couple times a year — around four to eight drinks — won’t be an insanely massive deal either.
You do need to avoid both sugary alcoholic beverages and drinking during the last couple hours before bed, however, and remember to count those 7 calories per gram — 100 calories a shot — toward your macros!