Lawsuits may be the only way to force U.S. foodmakers to produce healthier foods or curb ads that encourage over-eating, speakers at an obesity conference said on Thursday.

Two-thirds of adult Americans are overweight or obese. Poor diet and inactivity is now the No. 2 cause of preventable death, killing about 400,000 Americans each year, the government says. Fifteen percent of U.S. children are overweight.

Some speakers at an annual Consumer Federation of America conference on food and nutrition lamented that restaurant menus did not carry calorie counts and there were no restrictions on aiming advertisements for sugar-rich food at children or minimum-nutrition standards for children’s’ food.

“Trial lawyers and (state) attorneys general can be extremely helpful,” said Michael Jacobson, head of the consumer group Center for Science in the Public Interest, by “filing innovative suits” that prompt foodmakers to produce healthier foods.

Walter Willett, nutrition chairman at Harvard University, asked if food companies were liable for the obesity explosion with misleading ads or making foods with little value in a balanced diet.

Lawsuits were “the least desirable option,” Willett said in an interview, but “it may be the default.”

Barbara Moore, president of Shape Up, America, a group advocating physical exercise, said she was “a strong believer in taking responsibility for my eating behavior.”

Executives from PepsiCo Inc., Kraft Foods Inc and McDonald’s Corp. said their firms were modifying their products to reduce calories or unhealthy ingredients such as trans fats.

Michael Mudd, Kraft executive vice president for global corporate affairs, criticized “senseless finger-pointing” that “portrayed (obesity) as a morality play.”

Food executives said 78 percent of meals are eaten at home. Consumer groups said one-third of calories are eaten outside the home.

An aide to Florida Republican Rep. Ric Keller was optimistic Congress would pass a law this year to ban lawsuits that blame the food industry for making people fat. The House of Representatives passed Keller’s bill to ban the lawsuits and a companion bill is pending in the Senate.

“There should be common sense in the food court,” said Keller aide Mike Shutley, rather than going to court.

The proposed legislation would dismiss any existing lawsuits against the makers, distributors or sellers of food related to obesity claims and prevent any new ones from being filed.

Northeastern University law professor Richard Daynard said lawsuits against deceptive marketing were a way to reform the food industry. Daynard is involved in a movement to have the tobacco industry take responsibility for smoking-related deaths.