Special to The Washington Post I gave a talk in South Texas recently on the environmental virtues of a vegetarian diet. As you might imagine, the reception was chilly. In fact, the only applause came during the Q&A period when a member of the audience said that my lecture made him want to go out and eat even more meat. 'Plus,' he added, 'what I eat is my business -- it's personal.' I've been writing about food and agriculture for more than a decade. Until that evening, however, I'd never actively thought about this most basic culinary question: Is eating personal? We know more than we've ever known about the innards of the global food system. We understand that food can both nourish and kill. We know that its production can both destroy and enhance our environment. We know that farming touches every aspect of our lives -- the air we breathe, the water we drink, and the soil we need. So it's hard to avoid concluding that eating cannot be personal. What I eat influences you. What you eat influences me. Our diets are deeply, intimately and necessarily political. This realization changes everything for those who avoid meat. As a vegetarian I've always felt the perverse need to apologize for my dietary choice. It inconveniences people. It smacks of self-righteousness. It makes us pariahs at dinner parties. But the more I learn about the negative impact of meat production, the more I feel that it's the consumers of meat who should be making apologies. Here's why: The livestock industry as a result of its reliance on corn and soy-based feed accounts for over half the synthetic fertilizer used in the United States, contributing more than any other sector to marine dead zones. It consumes 70 percent of the water in the American West -- water so heavily subsidized that if irrigation supports were removed, ground beef would cost $35 a pound. Livestock accounts for at least 21 percent of greenhouse-gas emissions globally -- more than all forms of transportation combined. Domestic animals -- most of them healthy -- consume about 70 percent of all the antibiotics produced. Undigested antibiotics leach from manure into freshwater systems and impair the sex organs of fish. It takes a gallon of gasoline to produce a pound of conventional beef. If all the grain fed to animals went to people, you could feed China and India. That's just a start. Meat that's raised according to 'alternative' standards (about 1 percent of meat in the United States) might be a better choice but not nearly as much so as its privileged consumers would have us believe. 'Free-range chickens' theoretically have access to the outdoors. But many 'free-range' chickens never see the light of day because they cannot make it through the crowded shed to the aperture leading to a patch of cement. 'Grass-fed' beef produces four times the methane -- a greenhouse gas 21 times as powerful as carbon dioxide -- of grain-fed cows, and many grass-fed cows are raised on heavily fertilized and irrigated grass. Pastured pigs are still typically mutilated, fed commercial feed and prevented from rooting -- their most basic instinct besides sex. Issues of animal welfare are equally implicated in all forms of meat production. Domestic animals suffer immensely, feel pain and may even be cognizant of the fate that awaits them. In an egg factory, male chicks (economically worthless) are summarily run through a grinder. Pigs are castrated without anesthesia, crated, tail-docked and nose-ringed. Milk cows are repeatedly impregnated through artificial insemination, confined to milking stalls and milked to yield 15 times the amount of milk they would produce under normal conditions. When calves are removed from their mothers at birth, the mothers mourn their loss with heart-rending moans. Then comes the slaughterhouse, an operation that's left with millions of pounds of carcasses -- deadstock -- that are incinerated or dumped in landfills. (Rendering plants have taken a nose dive since mad cow disease.) Now, if someone told you that a particular corporation was trashing the air, water and soil; causing more global warming than the transportation industry; consuming massive amounts of fossil fuel; unleashing the cruelest sort of suffering on innocent and sentient beings; failing to recycle its waste; and clogging our arteries in the process, how would you react? Would you say, 'Hey, that's personal?' Probably not. It's more likely that you'd frame the matter as a dire political issue in need of a dire political response. Vegetarianism is not only the most powerful political response we can make to industrialized food. It's a necessary prerequisite to reforming it. To quit eating meat is to dismantle the global food apparatus at its foundation. Agribusiness has been vilified of late by muckraking journalists, activist filmmakers and sustainable-food advocates. We know that SOMETHING has to be done to save our food from corporate interests. But I wonder -- are we ready to do what must be done? Sure, we've been inundated with ideas: eat local, vote with your fork, buy organic, support fair trade, etc. But these proposals all lack something that every successful environmental movement has always placed at its core: genuine sacrifice. Until we make that leap, until we create a culinary culture in which the meat-eaters must do the apologizing, the current proposals will be nothing more than gestures that turn the fork into an empty symbol rather than a real tool for environmental change. James E. McWilliams, an associate professor of history at Texas State University at San Marcos and a recent fellow in the agrarian studies program at Yale University, is most recently the author of 'Just Food.' 