Source: Sergey Rasulov/123RF

I am interviewing Staci Giani who is 41 but looks 10 years younger. Raised in the Connecticut suburbs, she now lives with her partner Gregory in a self-sustaining eco-community deep in the mountains twenty minutes north of Old Fort, North Carolina. Staci radiates strength, and when she talks about food, she gets excited and seems to glow. She is Italian-American, attractive, and you want to smile when you talk to her. She tells me that she and Gregory built their own house, even the timber and milling the logs. I think to myself, "This woman could kick my ass."

Staci wasn't always so fit. In her early 30s, Staci's health started going downhill. After 12 years of strict vegetarianism, she began to suffer from anemia and chronic fatigue syndrome, and she experienced stomach pains for two hours after every meal. "I was completely debilitated," she tells me. "Then I changed the way I ate."

"Tell me about your diet now. What did you have for breakfast today?" I ask.

"A half-pint of raw beef liver," she says.

OK ... Staci is a bit extreme in her carnivory—these days she prefers her meat raw, and she eats a lot of it. But the transformation from hard-core vegetarian to meat-eater that Staci illustrates is surprisingly common. Indeed, according to a 2005 survey by CBS News, three times as many American adults admit to being "ex-vegetarians" than describe themselves as current vegetarians. This suggests that roughly 75% of people who quit eating meat eventually change their minds and return to a diet that includes animal flesh. It seems that for most people, vegetarianism is a phase rather than a permanent change in lifestyle. Why?

Perhaps because I was raised a Southern Baptist, I have always been fascinated by backsliders, so I decided to find out why so many vegetarians eventually give up their all-plant diet. To study the motivations of ex-veggies, Morgan Childers and I set up a website that included a survey related to eating. Then we put out a call for ex-vegetarians through Internet sites devoted to topics like health, , and the treatment of animals.

Over the next week or so, 77 former vegetarians took our survey. As is true of vegetarians generally, the majority of the participants were women. Their average age was 28, and on average, they had been vegetarian for nine years before for reverting back to eating animals. We asked the participants to indicate the primary reasons they quit eating meat in the first place and why they subsequently decided to give up their all-plant diet. They also had the opportunity to comment at length on the reasons for the changes they had made in their eating habits.

Why Did They Stop Eating Meat in the First Place?

As other researchers have reported about vegetarians, our participants originally quit meat for a variety of reasons. The most common reasons in our study were ethical concerns about the treatment of animals (57%), followed by health and environmental reasons (15% each). Fewer people stopped eating meat because they did not like the taste of animal flesh or because of social pressure from friends, spouses, etc.

Why the Ex-Veggies Resumed Eating Animals

The reasons the ex-vegetarians gave for reverting to omnivory fell into five categories.

Source: Graph by Hal Herzog

Declining Health. In his book The Face on Your Plate: The Truth About Food, Jeffrey Moussaieff Masson extols the health benefits of an all-plant diet. He writes, "Now at 68, several years a vegan, I find I have never been healthier. I weigh less than I did at 30; I am stronger than when I was 40; I have fewer colds or minor illnesses than at 50." While Masson may have thrived on a meatless diet, this is not always the case with vegetarians. In fact, 35 percent of our participants indicated that declining health was the main reason they reverted back to eating flesh. For example, one wrote, "I was very weak and sickly. I felt horrible even though I ate a good variety of foods like PETA said to." Another wrote, "My doctor recommended that I eat some form of meat as I was not getting any better. I thought it would be hypocritical of me to just eat chicken and fish as they are just as much an animal as a cow or pig. So I went from no meat to all meat." The most succinct response was by a man who wrote, "I will take a dead cow over anemia any time."

Hassles and Social Stigmas. About a quarter of our ex-veggies described the hassles they said were associated with strict vegetarianism. They complained that it was difficult to find high-quality organic vegetables in their local supermarkets at a reasonable price. Others began to resent the time it took to prepare meatless dishes, and some said they simply grew tired of the lifestyle.

A related reason for returning to meat consumption, one mentioned by 15% of our subjects, was that vegetarianism was taking a toll on their . The degree that vegetarianism and particularly moral veganism can screw up your day to day existence was nicely summed up in a New York Times op-ed by the philosopher Gary Steiner titled, appropriately, "Animal, Vegetable, Miserable." In describing his personal experience with giving up the consumption of animal products, he wrote: "What were once the most straightforward activities become a constant ordeal."

Irresistible Urges. About one in five of our participants had developed an irresistible urge to taste cooked flesh once more. This occurred even among some long-term vegetarians. Participants talked about their protein cravings or how the smell of sizzling bacon would drive them crazy. One, for example, said, "I just felt hungry all the time and that hunger would not be satisfied unless I ate meat." Another described his return to meat in mathematical terms: "Starving college student + First night back home with the folks + Fifty or so blazin' buffalo wings waiting in the kitchen = Surrender."

Shifts in Moral Thinking. About half of the respondents originally gave up meat for ethical reasons. Yet only two of our ex-vegetarians said changes in their views of the of killing animals motivated their decision to resume meat consumption. In fact, most of the former vegetarians were still concerned with animal protection and the ethical issues associated with eating animals. The participants' original reason for giving up meat did affect their present level of meat consumption. Individuals who had given up eating meat primarily for social reasons indicated that they ate meat much more frequently than did people who originally became vegetarian for ethical or environmental reasons.*

The Bottom Line

For most people, the draw of meat is powerful—often irresistible. This is not a justification for slaughtering creatures because they happen to taste good. Philosophers correctly warn against committing "the naturalistic fallacy"—assuming that because a behavior is "natural," it is also ethical. In fact, I believe the case against eating other creatures is strong on moral, environmental, and health grounds. Why then do even most vegetarians eventually cave to the desire to eat animal flesh? Is meat-eating in our ? I will take this question up in a future PT blog. Stay tuned.

Hal Herzog is Professor of Psychology at Western Carolina University and the author of Some We Love, Some We Hate, Some We Eat: Why It's So Hard To Think Straight About Animals.