Can keto and alcohol coexist? Is there anything we need to take into consideration?
First things first, does alcohol inhibit ketosis?
There are very few human studies that even look at this issue. Let’s go over the best one I could find.
How Does High Intake of Alcohol Affect Ketosis?
A 2002 study out of Poland examined the bodies of 16 recently deceased people who had died from hypothermia, mostly alcohol-induced. Most were alcoholics. They found that ketone levels and blood-alcohol levels were inversely proportional. The higher the blood alcohol, the lower the ketones. The higher the ketones, the lower the blood alcohol.
In the discussion section, the authors explain:
Liver cells ‘‘engaged’’ in ethanol utilization do not accumulate larger amounts of Ac-CoA (which is a substrate for ketogenesis) because an increase in the NADH/NAD ratio during ethanol oxidation inhibits b-oxidation of fatty acids, and the acetate created from ethanol is activated to AcCoA mainly in the non-liver tissues which cannot produce ketone bodies.
In other words, at a high enough intake, alcohol metabolism supersedes and inhibits ketogenesis because both processes occur in the liver along similar pathways. The Polish study is an extreme example—alcoholics, hypothermia, death—but the basic mechanism is sound.
What About Normal (Moderate) Intake?
In real world situations, however, where people are having a drink or two, low-sugar alcohol (red wine, spirits) is unlikely to derail ketosis. Sugary drinks will inhibit ketosis because of the sugar. Alcohol-induced junk food bingeing will inhibit ketosis because of the junk you’re eating. But it appears to take some serious doses of ethanol to make a noticeable dent in your ketone production. Even then, a degree or two less ketosis isn’t the end of the world (unless you have a serious health condition warranting constant ketosis, in which case are you sure you should be drinking?).