The US House of Representatives has voted 276-139 for a bill that would prevent lawsuits against the food industry for making people fat.
Two-thirds of US adults are either overweight or obese, a new study says
The so-called Cheeseburger Bill bans frivolous lawsuits against producers and sellers of food and non-alcoholic drinks arising from obesity claims.
The bill supporters say consumers have to realise they cannot blame others for the consequences of their actions.
Critics say the food industry now does not have to worry about public health.
The vote came a day after a new study said obesity was likely to become the nation's biggest preventable killer, overtaking smoking.
The study found that poor diet and lack of exercise caused 400,000 deaths in the US in the year 2000 - a 33% jump since 1990.
Two thirds of US adults and nine million children are either overweight or obese, the study said.
On Wednesday House Majority leader Tom DeLay praised the passage of the bill, which is formally called the Personal Responsibility in Food Consumption Act.
After the vote he said "Ronald McDonald made me do it" should never be considered the basis for a lawsuit.
The bill's sponsor, Florida Republican Representative Ric Keller, said the legislation was all about "common sense and personal responsibility".
The first US fast food lawsuit was filed in 2002 by a New Yorker who blamed his frequent visits to McDonald's for his obesity and diabetes.
Since then, there have been a number of similar cases across the country.
The new bill has also the backing of the White House and much of the food industry.
"This issue isn't about any restaurant or any particular food, it's all about personal responsibility and individual decisions," McDonald's spokesperson Lisa Howard said in a prepared statement.
But mostly Democratic critics - who have the support of a number of consumer groups - argued that the courts, not Congress, should determine when "obesity" lawsuits were frivolous.
They pointed out that all the lawsuits had been eventually dismissed.
Several overweight teens recently tried to sue the McDonald's fast food chain
Opponents also said the bill a clear signal to the food industry that it did not have to worry about the public health.
"That's the wrong message," said Democrat Representative James McGovern.
The bill still has to be approved by the Senate. In the past senators have blocked measures to protect certain industries from lawsuits.