Sort of, and only for a short period of time. David Levitsky, a nutrition professor at Cornell University, said the levels of enzymes that digest protein and fat can drop when you stop eating meat. But they quickly rise again once you fall off the wagon. “If you haven’t eaten meat for a while, it’s going to stay in your stomach longer,” but it’ll take only a day or two to recover your meat-digesting ability entirely, he said.

Longtime vegetarians report nausea and other gastrointestinal symptoms after consuming meat, intentionally or not, but several experts said they knew of no studies on the matter. The symptoms could be the result of those enzymes suddenly being asked to work harder than they have in a while, but Michael Greger, a clinical nutritionist and director of public health and animal agriculture for the Humane Society of the United States, thought it could also be psychosomatic. “What’s really happening is they’re thinking of some poor animal somewhere, and this may actually cause them to throw up,” Greger said.