That’s a good question. When I asked the endocrinologist a similar question he said a minuscule amount technically broke a fast; however, from a practical standpoint it probably wouldn’t knock a person out of ketosis.
The question is how long do you have to go between imbibing before you trigger an accumulative effect? All I know is that it takes 12 hours after the last bit of food exits the esophagus before insulin levels drop. It’s the reason that the minimum IF schedule is now a 13:11. I’ll ask the doc next week. Otherwise, I got nothing.