There comes a point early on in “Food, Inc.” where you have to decide if you want to know.

Everyone has heard the stories about people killed by bacteria in factory-produced hamburger. The February tomato, bred to look like a tomato but they have the resilience of a racketball, isn’t news. American obesity has become such an epidemic that it’s accelerating the cost spirals of the health care system.

FOOD, INC.

Four stars

STARRING: Michael Pollan and Eric Schlosser

DIRECTOR: Robert Kenner

RUNNING TIME: 94 minutes

RATING: PG

THE LOWDOWN: While American consumers fatten themselves on industrial food, regulators ignore problems to ensure corporate profits.

Yet we still find ways to turn away from the unsettling back story of our meals. Deny, deflect, ignore.

But “Food, Inc.” gives viewers no choice. Turn away, or listen and watch, as the nausea kicks in. Built on the investigative food reporting of Michael Pollan (“In Defense of Food”) and Eric Schlosser (“Fast Food Nation”), the documentary lays bare the price the United States is paying for cheap food.

The combination of lobbyist-driven government subsidies for corn and sugar has made them the cheapest possible ingredients and feeds of choice, for a factory food system that only cares about the bottom line.

To get that 99-cent double cheeseburger on the drivethrough value menu, cows are given hormones to make them fat, and other pharmaceuticals to let them grow in conditions that would kill them otherwise. The raw meat was probably treated with ammonia or something like it, to kill the bacteria.

The chicken that gave you the crispy chicken sandwich was probably raised in the dark. Bred for its breasts, it could hardly have walked, if it had room to move. The antibiotics it’s fed to keep it breathing end up right there in every bite of your sandwich.

Why can you get a double cheeseburger for 99 cents, when a simple head of broccoli costs so much more?

The answer, Pollan says, is that American food is not a free market. “The reason those calories are so much cheaper is that they’re the ones that are so heavily subsidized,” he says. That makes cheap food fattening food, Pollan says. “That’s why the best predictor of obesity is income level.”

“Food, Inc.” is a movie with a message, but director Robert Kenner doesn’t sledgehammer viewers like a bull in an abattoir. He lets the people involved in the food system, like the former chicken farmer and the woman who lost a son to a contaminated fast food hamburger, tell their stories. Then the concerns that Pollan and Schlosser raise are connecting the dots.

“The industry doesn’t want you to know the truth about what you’re eating,” Schlosser says early on, “because if you did, you might not want to eat it.”

The truth matters, he says, because “food is becoming much more dangerous in ways that are being deliberately hidden from us.” When the Bush administration put a former meatpacking industry lobbyist in charge of the U. S. Department of Agriculture, the agency that was supposed to keep the meatpacking industry from endangering consumers, fox-in-charge-of-henhouse drove federal policy.

It’s harder for even well-meaning regulators to get a handle on the problems because a small group of international companies control most of the food system, from seed to supermarket, he said.

“Food, Inc.” feels like a hefty film because what you eat, and how you eat it, makes you an individual in ways that your hairstyle or your musical choices never will. What you put in your mouth becomes your muscles after all, your eyes, your bones, your breath.

The very intimacy of food makes eating — for hunger, for celebration, for solace — a force powerful enough to rival any other driving hunger in the lives of many.

That’s why “Food, Inc.” hits home like a sucker punch to the solar plexus. The food you love, Kenner argues, isn’t what you thought it was. It’s been cheating on you in ways that could poison you and the planet, and it’s making the owners of a few huge corporations rich.

If you can swallow that, you might settle your stomach after all. The next drivethrough is right around the corner.