The lawsuit, filed by lawyer Samuel Hirsch in a Manhattan federal court, alleges that McDonald's violated New York state's consumer fraud statutes by deliberately misleading consumers into thinking their cheeseburgers and other products were healthy and nutritious.
It says the company did not adequately provide information on the health risks associated with fast food, and the children developed health problems such as diabetes, high blood pressure and obesity from eating its products.
McDonald's has asked the court to dismiss the case.
More suits feared
Mr Hirsch said the lawsuit raised "serious issues".
"They have deliberately withheld information."
Mr Hirsch says that, if the case goes to trial, he will seek to turn it into a class action suit, meaning it can represent other children in the state who claim they have developed health problems stemming from McDonald's food.
If successful, fast-food companies fear that it could trigger a rash of further suits and huge payouts to victims - potentially running into billions of dollars - similar to those that have severely damaged the tobacco industry.
The mother of one of the children, who at the age of 15 weighs more than 180 kilograms (400 pounds), said in papers filed before the court that "[I had] always believed McDonald's was healthy for my son."
Another teenager ate every meal at McDonald's for three years while living in a homeless shelter, the Associated Press news agency reported.
Obesity epidemic
However McDonald's has asked presiding Judge Robert Sweet to dismiss the suit, describing it as frivolous.
"People don't go to sleep thin and wake up obese," McDonald's lawyer Brad Lerman said.
"The understanding and comprehension of what hamburgers and French fries do has been with us for a long, long time."
The action follows an earlier suit filed in July by a group of overweight Americans who sued several US fast food giants accusing them of knowingly serving meals that cause obesity and disease.
The lawsuit - filed in New York State Supreme Court in the Bronx - said that McDonald's, Burger King, Wendy's and Kentucky Fried Chicken misled customers by enticing them with greasy, salty and sugary food.
A recent assessment of obesity in the US found that more than half of all adult Americans were overweight.
About 54 million adults were classified as obese - that is people who are about 15 kg or more over the healthy norm based on height - and hundreds of thousands of deaths each year are attributed to obesity-related diseases.
The situation is so serious that President George W Bush has urged Americans to follow a fitness regime to assuage the country's spiralling health care costs.