California has become the first state to outlaw the use of trans fats in restaurant food.
Gov. Arnold Schwarzenegger signed the measure, but it won't go into effect on January 1, 2010.
Violators will fined up to $1,000 for using oil, margarine or shortening that has trans fats.
Some customers are not too pleased with the new law.
"My wife tells me what to eat, I don't need my governor telling me what to eat," one Californian said.
The California Restaurant Association opposed the bill, but has no plans to challenge the new law.
A spokesman for the group says restaurants are already doing away with trans fats in order to please customers.