Those extra pounds - are they government's business?

As America's waistline expands and the anti-obesity movement gains momentum, what you eat may soon slip out of the private domain and into the public. Nobody will be regimenting your diet, but the government may start offering more pointed advice and regulating what goes into preprepared foods, among other things. Proposals include a tax on high-fat, low-nutrition food; better school meals; and nutrition labels on restaurant menus.

Having the government in your kitchen wouldn't be the first time private habits have come under outside scrutiny. Tobacco, alcohol, and drugs have all gone that route at various points in US history. But where did personal responsibility fall off the bandwagon?

The shift of private behavior to public oversight, with new legislation to enforce it, happens in a quantifiable way, says Rogan Kersh, political scientist at Syracuse University's Maxwell School, who is writing a book on the politics of obesity.

The first and most significant of several triggers, he explains, is social disapproval. For instance, "it used to be sexy and desirable to smoke.... [Now] you're committing some grave moral wrong."

As disapproval gains momentum, he says, "public health crusades start to build around these behaviors": Sometimes the science is accurate (the medical establishment is unanimous on the evils of smoking); sometimes the science is a mixed bag (some studies suggest that alcohol isn't as dangerous as the Prohibitionists claimed); and sometimes the science is completely spurious (Victorian physicians warned that too much sex would maim, blind, or kill).

Despite almost two thirds of Americans being overweight, the US is paradoxically one of the most antifat biased countries in the world. And that bias has only intensified in recent decades. Only a couple of brief periods in the 20th century showed a return to the acceptance of corpulence, Professor Kersh says, and both were after the world wars when Americans had undergone deprivation.

With social disapproval already widespread, medical science is reinforcing that view. Numerous studies and articles, some more alarmist than others, point to the health consequences of being heavy.

The message is no longer that being overweight is not good for you. It's now, "you're killing yourself through your obesity and the government must help you" to change, Kersh says.

That sort of shift in reasoning, reframing the problem in terms of a toxic food environment rather than weak will and failing personal responsibility, is key to the government stepping in. The individual is no longer blamed for not pushing back from the table. It's now a social problem.

What has helped accelerate that redefinition is the medical bill for dealing with weight-related illnesses, which reached $117 billion last year, according to the US surgeon general, and may soon surpass the toll on healthcare taken by smoking. "When something becomes an economic problem in this country, government tends to act in a more urgent way than if it's a different kind of problem like constitutional rights."

"The point is, even though I'm not obese I'm paying for people who are. This really burns Americans and they want their policymakers to act in response," Kersh says. Already, more than 140 anti-obesity laws have been introduced in state legislatures this year.

But Sandie Sabo-Russo disputes the health-bill figure. "If a person is large-sized and goes to the doctor for something that has nothing to do with their size, it's often trumped up to be obesity related," says Ms. Sabo-Russo, a member of the board of NAAFA, the National Association to Advance Fat Acceptance and the largest obesity-rights organization in the US. "I don't trust what we're getting on that information."

She also points out the complexity of the issue. Being obese, or overweight, she says, is not always about food, "There are as many reasons as to how or why people are fat as there are fat people."

As for studies on obesity and its consequences, she questions their accuracy because many come from sources with a vested interest. "The first thing we try to look at when a new study comes out is who funded it. If it's funded by Weight Watchers International [for example], I'm not sure I'm going to believe what it says."

As societal pressure builds, and government reluctantly eyes new legislation, the courts are already grappling with obesity issues. More and more class-action lawsuits are taking aim at the food industry. And of the 10 major cases filed so far, mostly consumer protection suits, five have had some success. McDonald's, for example, had to fork over $12 million for not disclosing that its fries were cooked in beef fat. Pirates Booty paid $4 million over a cheese snack that misstated the amount of fat it contained.

Even though no personal-injury suits have yet won in court, a case brought against McDonald's elicited an unusual response from the judge. A man who sued the fast-food chain when he gained large amounts of weight lost his case twice. But the judge spelled out what the plaintiff could have done to make the case stronger and suggested ways obesity cases could be argued.

"With judges doing that, trial lawyers are catching on and it's only a matter of time before they strike," says Kersh. The class-action suit, Kersh adds, has its roots in social movements that once took to the streets to demand change. Now large numbers of people can gather together through the courts.

Another historical pattern Kersh has identified in this gradual shift away from personal responsibility is the self-help movement. Twelve-step programs which usually spring up in response to medical warnings - Alcoholic Anonymous, Nicotine Anonymous, Overeaters Anonymous and so on - encourage Americans to live healthier lives. When that encouragement doesn't bear fruit fast enough, the users (in this case, the fat) tend to get "demonized" and so do the producers - the food and restaurant industries, who throw temptation the public's way.

The government has responded to public concern by telling people to exercise more and eat less - noncontroversial advice, as critics have noted, which won't rock the boat with the food lobby.

With the demonization of big tobacco fresh in memory, however, McDonald's and others are trying to minimize their liability by cutting portion sizes, ending supersizing, eliminating school marketing, and offering more salads. The fast-food industry is still big on individual choice, and even NAAFA's Sabo-Russo doesn't want the government legislating menus.

The danger of this growing push to trim the fat, Kersh says, is that it takes such a head of steam to change laws that the momentum often carries action beyond what's necessary. He cites Prohibition's 15-year fiasco and the zero-tolerance drug sentencing of the 1980s that is now being rolled back.

"Demonization makes very powerful politics, but it makes miserable public policy. You get these all out prohibitions, zero-tolerance policies which in practice are unrealistic and quite unjust," he says.