Health experts say obesity has become a global pandemic that will strain health budgets as more people suffer from illnesses such as diabetes and heart disease.
Paul Cimmet, the chairman of the International Congress on Obesity, told conference participants in Australia Sunday obesity is an "insidious, creeping pandemic" that is "engulfing the entire world."
Participants said wealthy countries lead whe world in overeating and not exercising enough, but that developing nations are fast adopting these bad habits.
The World Health Organization says there are more fat people in the world than hungry people.
Experts say the traditional methods to lose weight, including diet and exercise, are not enough. They say governments must adopt healthier national policies to tackle obesity.
About 2,000 participants are taking in the conference, which ends Friday.
Some information for this report was provided by AFP and AP.