Jamie Oliver has called for a "global movement to make obesity a human rights issue" and urged a million people to sign a petition.
The food campaigner and celebrity chef wants obesity to be on the agenda at a UN summit on disease and compared the "epidemic" to the Aids crisis.
Addressing the One Young World conference in Switzerland, Oliver, 36, said: "Obesity needs to be on every government agenda.
"It should be as important as the fight against Aids and climate change. It has to become the national health priority."
The young people with leadership potential who attended the summit in Zurich heard the TV cook, known as the Naked Chef, say: "We need a global movement to make obesity a human rights issue. We need to get people worried and angry all over the world, and create their own networks for change."
His aim is to encourage heads of state and the UN Secretary-General at the summit on non-communicable disease in New York on September 20 to "sit up and take notice".
He said: "I believe that together we can make some real noise ahead of this meeting of experts. Help me to take the 'food revolution' global, and get one million signatures on my petition."
He told the audience he wanted to tackle the global problem of obesity and related diseases, help countries keep their traditional diets, and educate people about food.
"Diet-related diseases are two of the top five causes of premature death for people under 60 years old. They look set to create an absolute catastrophe over the next 30 to 40 years if nothing changes."
The TV chef from Essex warned the young leaders at the forum: "For the first time in history, being too fat, being overweight, is killing more people than being underweight."