People choose to give up meat and become vegetarians for myriad reasons. Sometimes it’s to cut back on the cholesterol and saturated fat found in their favorite meat products; other times it’s because they’re opposed to the environmental and moral impact of the meat industry itself. Likewise, there are just as many reasons why a number of vegetarians decide to go back to an omnivorous lifestyle. As a vegetarian, I’ll freely admit that there are times when few things sound more satisfying than a big ol’ cheeseburger. But part of my reluctance to return to the world of meat (other than, you know, my reasons for becoming a vegetarian in the first place) stems from the potential havoc something like a cheeseburger would wreak on a digestive system that hasn’t confronted red meat in many years.
I’ve heard anecdotes about vegetarians accidentally or intentionally eating meat and having severe stomach issues afterward. I also know of quite a few former vegetarians who returned to omnivorous diets and experienced zero physical repercussions. So do people who forgo meat then temporarily lose their ability to digest it, or is that just a myth?
The Digestive System Doesn’t Like Change
Within the human gastrointestinal tract lie tons of bacteria called “gut flora” that help break down anything that’s consumed. Some types of flora build up more than others, based on one’s regular diet. The same is true of the enzymes that GI tract cells secrete and that also help with digestion. So if someone stops eating meat for a significant amount of time, it’s possible that the amount of enzymes dedicated to animal-protein digestion might reduce a little to compensate for the increase of other food groups in the system. But that’s by no means a permanent condition. “The gut senses what it needs to secrete,” says Rania Batayneh, a nutritionist and wellness coach based in San Francisco. “If you haven’t consumed a type of food in a long time and you eat it, it just might take a longer time to digest, especially with meat.”
Toni Bloom, a registered dietician who teaches sports nutrition at San Jose State University, also believes it has more to do with the diet shift. “Anytime you put something different in there, it can upset the balance. It’s not a bad thing; it’s that your body has to adjust,” she explains. Basically, making radical changes to one’s diet is going to throw the digestive system for a loop, at least in the beginning. Take someone who subsides mostly on junk food: One day, he decides to eat more healthfully and fills up on salads, whole grains, and beans instead. Even though he’s adopted a much better diet, it’s likely he’ll experience bloating, gas, and nausea—the same symptoms vegetarians often report after eating meat again for the first time—for the first few days. That’s because his system has to work harder than usual to break down those unfamiliar, fibrous substances.
