(FORTUNE Magazine) – And how is the food at the Calhoun School in Manhattan this year, now that Chef Bobo is in charge?

"It's awesome," says a student diner. "The hot dogs don't bounce."

That's an admirably succinct review, and no doubt accurate, but it doesn't quite capture the big picture. When Calhoun's administrators decided last year to drop their commercial catering service, they heard about a man called Chef Bobo, a charismatic teacher at the French Culinary Institute with an ambition to work with children. Calhoun's headmaster hesitated--"Having a clown as a chef was not my idea of trouble-free administration," he says--but he hired Chef Bobo and several students from the institute. Since this school year began, the team has been systematically reeducating the palates of more than 500 kids in grades two through 12. What the chefs are doing is simple--they're making nice lunches from scratch--but it's also profound: an object lesson in how to reverse the metabolic disaster of the modern American diet.

On a recent Friday the scene in Chef Bobo's lunchroom is the kind of thing school cafeterias probably dream about at night. On the menu are vegetable soup, green beans with shallot butter, potato salad with scallions, and baked salmon with citrus butter. Dessert is a tiny piece of superb chocolate cake. The students are eating it up, as Marion Nestle, the well-known nutritionist, can attest--she's making a cameo appearance over in a corner rooting through a trash bin, confirming that hardly anything is going to waste. As this is the last day of school before Christmas break, Chef Bobo is receiving handmade cards from grateful students with variations on the theme "We love your food!"

"This is completely different from what they had before," says the chef, a New Orleans native with a big smile and a gold earring. "The first two months I would not allow any ketchup or mayonnaise in the lunchroom. Students constantly asked for it, but I would say, 'Sorry, I don't believe in ketchup.' Ketchup has more sugar than ice cream. I wanted them to taste what food really tastes like. Now they don't ask for it anymore."

In Chef Bobo's kitchen, vegetable stock is made every morning. Bread and muffins are freshly baked. Each day the kids are fed a soup, an animal entree, a vegetable, a starch, and fresh fruit. Ninety percent of what's served is vegetarian, organic whenever possible. At the start of the school year the students were consuming one case of vegetables a day. Now that's up to four cases, and a fifth may be needed.

"The philosophy that comes out of the kitchen is to eat wonderful things moderately," says Steve Nelson, the headmaster. There have been other benefits. Teenage girls are eating the food because they know it won't make them fat. Teachers are mingling with students at lunch instead of going out. "The kids tell me that when they go to McDonald's or Burger King now, they get sick to their stomach. That's one of my goals," Chef Bobo says. Adds Nelson: "We have a cooking club now, so we have high school students who, instead of going to a rave party downtown and consuming large quantities of ecstasy, are having a dinner party and consuming large quantities of herb-crusted cod."

As the Calhoun experience shows, it's easy as pie to change the way people eat.

Oh, sure, you might say, but this is a Manhattan private school that can afford an elitist extravagance, right? Chef Bobo is even a minor local celebrity: The New Yorker recently ran a little profile of him, noting that he also works as Derek Jeter's personal chef during the baseball season.

But surprise: Calhoun's food costs per child are almost identical to what they were before. The school pays more for ingredients, but servings are smaller, little goes to waste, and because the chefs are employees, there's no catering-company overhead.

The broader point is that human diets are eminently changeable; they change all the time, and there is nothing inexorable about the national drift toward bloat. There is also nothing immutable about the swill that people buy in supermarkets and restaurants. A generation ago it was almost impossible to get a good cup of coffee in America. Yuppies fixed that. Beer too.

What will it take to transform our diet on a national scale? The problem is huge and depressingly simple: The U.S. food industry provides about 3,900 calories per person per day (the figure is for 2000, the latest available). Allowing for waste and losses in cooking, the USDA estimates that the average American consumes roughly 2,750 calories per day--a full Big Mac beyond its recommendation of 2,200 calories for most children, teenage girls, active women, and sedentary men. Of course, diet and exercise are matters of individual choice, but cultural circumstances--car travel, post-industrial jobs, passive entertainment--push us collectively toward eating more calories than we burn. So do the roughly $4.5 billion a year the food industry spends on advertising and the $50 million a year it spends lobbying in Washington, D.C.

Successful dieters, like those in the National Weight Control Registry--a database of more than 2,000 people who have lost at least 30 pounds and kept them off for at least a year--generally report that their weight loss was triggered by a specific incident or milestone, often painful. Is there some incident that could make us change the way we eat as a nation? Some dietary Sputnik on the horizon that will do for food education what the Soviet satellite launch did for science education? An across-the-board defeat in the Olympics, perhaps?

Actually, it may already be here, in the epidemic of obesity and the rise of Type 2 diabetes (which used to be called "adult-onset") in children. The Surgeon General's 2001 Call to Action against obesity reported that 13% of young children and 14% of adolescents were overweight, with the number of overweight adolescents having tripled in two decades. That has changed the politics of the debate: With children in the picture--children spammed every day with marketing messages for sugar and fat--it is no longer so simple to argue that diet is purely a matter of individual responsibility.

As long ago as the early 1980s, Romans watching American tourists walk by could be overheard muttering, "Culo Americano" (American butt). It was about that time, in fact, that the USDA recorded the first big jump in calories in the U.S. diet since it began tracking food consumption in 1909. Today the biological issue is no different than it was then. But since the Centers for Disease Control identified obesity as an "epidemic" in 1999, the politics of girth appears to be changing.

Declaring an epidemic would seem to call for a policy response. Some school districts in California have banished soft drinks from vending machines. Activists are pushing for restrictions on the advertising of junk food to children. They are also getting ready to fight for changes in the Food Guide Pyramid, in the USDA's dietary guidelines, and in the federal school lunch program, all of which are up for review in the next few years. And, of course, some Americans are taking the fat fight to the courtroom (see previous story).

The uproar has only begun, says Kelly Brownell, director of the Yale Center for Eating and Weight Disorders. "The first thing that's necessary is for the public to be sensitized and even angry about the current situation. The key to getting mad is having victims. And the victims are the children."

Brownell, who will soon publish a book on what he terms the "toxic food environment," called a decade ago for taxing junk food the way cigarettes and liquor are taxed. His proposal was widely derided as the "Twinkie tax," but now nutrition experts bring it up routinely in conversation. "The two things I could think of doing would be, one, prohibit fast food and soft drinks in schools," he says. "The other would be to create a nutrition superfund to advertise and market healthy food. You could pay Britney Spears to promote apples and oranges rather than Pepsi. And you could pay Michael Jordan to promote vegetables rather than McDonald's. Then at least it would be closer to a level playing field."

Brownell has a point: Healthy food is not just more expensive than unhealthy food but less convenient. Imagine, for instance, that a crazed vegan were to burst into your office with a gun and demand that you produce, within four minutes, some fresh fruit. Could you do it? How about a soft drink?

There's no reason food companies should be expected to look out for the nation's health. On the contrary, the market's logic suggests that if food companies are to grow, so must we. In a way it's a mirror image of the problem of overfishing: Each restaurant and food company has an incentive to get more stuff onto our plates; an individual company, like an individual fisherman, has no interest in cutting back for the benefit of a species. Only in this case the species that suffers isn't swordfish. It's us.

"We have national health goals for reducing obesity but no implementation plan," says Marion Nestle, who chairs the Department of Nutrition and Food Studies at New York University. "The government could develop an implementation plan and assign an agency to be responsible and accountable for it. We don't have that now."

There is something new in Washington, though: a Senate majority leader who is a transplant surgeon--that is, a doctor who has had to make up for the harm some people do to themselves. Last year Senator Bill Frist introduced a bill that would establish grants to promote improved nutrition, physical activity, and obesity prevention. It didn't pass, but an aide to the Senator says some form of the bill will be introduced in the new Congress.

The main federal response to the obesity epidemic, however, is coming from Health and Human Services Secretary Tommy Thompson--who is handing out pedometers. "I did 10,876 steps yesterday, and I've done about 4,000 so far today," Thompson says. "Tonight, if I haven't gotten my 10,000, I'll get on the treadmill."

Besides that, Thompson says he's trying to use the "bully pulpit" of his office to educate the public about diet and exercise. He met recently with the National Restaurant Association and some of the big food and soft drink companies to talk about nutrition, and last summer his office launched a $190 million media campaign to encourage "tweens" (9- to 13-year-olds) to be more physically active.

As much as it may advocate exercise, there is no chance that this administration will take forceful steps to change the diet side of the equation. "I don't think you're going to win this fight just by bludgeoning the fast-food companies," Thompson says. "There's not much of a flavor in Washington, D.C., for tax increases." In a recent speech to members of the Grocery Manufacturers of America, he said, "Rest assured, I don't, and the administration doesn't, want to mandate anything. We're not talking about government regulating what you produce or how you sell it."

It has been a lousy year for burgers and fries. McDonald's stock is trading near its seven-year low, its chief executive quit, and in the nine months ended Sept. 30 its global same-store sales were off 2.1%. Burger King, meanwhile, was sold to an investor group at a $700 million discount from the original sale price.

Subway, promoting its (foot-long) sandwiches as a lower-fat alternative to burgers, now has more U.S. franchises than McDonald's. Wendy's has added enough low-fat items to its menu to earn a nice profile in the magazine of the American Diabetes Association.

Something like a backlash is certainly underway in the food business, and it leads to curiosities. Seven-Eleven stores in California are selling sushi. Pepsi is pushing organic Tostitos. Whole Foods Markets, the Austin supermarket chain that sells mostly natural and organic groceries, led its sector with profit growth of 20% last year. Heinz and General Mills are waging a premium-priced organic ketchup war. A couple of weeks ago a New York City outlet of Pret A Manger, a sandwich shop chain based in London, was serving duck liver pate with figs on small fresh baguettes. Pret A Manger is 33% owned by McDonald's.

So far, though, all this is change at the margins. From a health standpoint, America's food supply is still seriously out of whack. According to Department of Agriculture data for 2000, the most recent available, the national food supply (both domestic and imported) provided 280 pounds of fruit per person. Adjusted for losses and waste, that amounted to less than half the per person per day minimum for fruit recommended by the Food Guide Pyramid. Yet consumption of added sugars reached 31 teaspoons per person per day, far above the six- to 18-teaspoon maximum recommended. As Phillip James, chairman of the World Health Organization's International Obesity Task Force, has observed, Americans who want to eat right have to behave "abnormally."

The government isn't doing too well in its effort to explain what healthy eating involves. Take the Food Pyramid's recommendation to eat six to 11 servings a day from the grain group. What is a serving? "I don't know," says Health and Human Services Secretary Thompson. "The actual size depends on the individual person." In the Food Pyramid, which the USDA developed, a serving of cooked pasta is one-half cup, cooked. In the Nutrition Facts label on a box of pasta, which is regulated by the Food and Drug Administration, it is twice that. No wonder diners are confused.

For the many people who don't pay especially close attention, a serving is what you're served. And as Nestle and her NYU colleague Lisa Young showed in a study published last year by the American Journal of Public Health, "Restaurants are using larger dinner plates, bakers are selling larger muffin tins, pizzerias are using larger pans, and fast-food companies are using larger drink and French-fry containers." Says Nestle: "When I'm giving a speech, I hold up this little white cup that's eight ounces, the standard Agriculture Department serving size for soft drinks. You can't even get these cups anymore. Then I hold up this great big soft drink cup, which if it doesn't have too much ice in it contains 64 ounces and provides 800 calories. Even when I do this before an audience of nutrition professionals, everybody says, 'Wow!' There's this big disconnect around portion size and calories."

"As a civilization we've never had huge amounts of food before. Used to be, in the winter you had to eat dried salmon or figs or grandma," says futurist Bruce Sterling, author of the new book Tomorrow Now. "I don't think there's ever been a society that when presented with an endless stream of free cheeseburgers would have said, 'No, thanks, I'll go back to my gruel here.'"

Abundant food has benefits, Sterling points out. "People are fatter, but the people who are strong are also stronger. Actors and actresses are really buff now. You go look at an old Elvis movie, and he's supposedly this avatar of masculinity, and he's got baby fat all over his torso. I mean, even Leonardo DiCaprio, who is supposedly feminine, is in better shape than Elvis was. DiCaprio could kick Elvis's ass."

Sterling and others predict that if the obesity epidemic is ever to be reversed, it will be through some technological fix like a "fat pill" rather than a general expression of national willpower (see box). The very idea of willpower is under attack by some researchers, who argue that the brain may dictate appetite the way it does other sorts of behavior, like drinking and excreting the right amounts of water to maintain a balance in the body.

"It's like that wonderful Garth Brooks lyric 'Long-neck bottle, let go of my hand,'" says K. Dun Gifford, founder of Oldways Preservation and Exchange Trust, a Boston group that advocates a return to traditional eating patterns, especially the Mediterranean diet (lots of olive oil, veggies, and grains). "I think of it as a railroad track. The track has two rails. We've progressed very far along on the nutrition science rail, but we're nowhere on the behavioral science rail, so the train ain't running."

Of course, cultures do evolve. Perhaps a decade from now this health calamity will have turned us all into mindful epicures. But at the moment we're on our own, and we're going to have to pay attention. As Gifford puts it, "For lifelong health you've got to teach people about their own individual calorie thermometers." One associate of this magazine recently lost 30 pounds by sticking to a diet consisting only of foods he doesn't like. But he's a humorist, so he can do that. What tools are available for the rest of us?

Actually there is an interesting new one, developed by a Colorado heart-lung transplant surgeon named James Mault. When Mault was working his way through college in the 1980s, he had a job at a hospital wheeling around a "metabolic cart," a big, cumbersome machine for measuring patients' resting metabolic rates--the daily calories their bodies burned when at rest. Some of the patients were being fed intravenously, with their caloric needs determined by height-and-weight tables developed in 1919. With his machine, Mault found that some people's actual caloric needs deviated by as much as 1,000 calories a day from what the tables predicted: Despite the hospital's best efforts, some were being overfed, and others starved. He dreamed of a simple handheld device that would measure a person's resting metabolic rate (RMR) and indicate precisely how many calories a day that person could take in without gaining weight. "You can't manage what you can't measure," he points out.

It took years before Moore's law caught up with Mault's vision, but eventually he found chips and sensors cheap enough to do the job, and in 1998 he founded HealtheTech to market a new handheld RMR meter, called BodyGem. It's being used at fitness and health clubs around the country. You breathe into the gizmo for a few minutes, and it tells you your RMR. "This is the next vital sign," Mault avers. "Before we had a measurement for cholesterol, we didn't know how to treat it. Before we could measure your RMR, we didn't know precisely how many calories you need."

It's an interesting breakthrough. Once you know your personal calorie budget, you tend to look differently at the out-of-control national buffet.

And that's what it's going to take, for now at least. Big government, big food, big pharma--none of them is going to help us get small. So: Eat like a Frenchman. Walk like a New Yorker. And think like Chef Bobo. "If you give kids interesting food that's been seasoned well and cooked well, they're going to love it," he says. "And this has been a love affair."

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