The aim of the new scheme was to create a "healthy England," he said.
Among the ideas being piloted is a loyalty card which allows people to earn points by buying healthy food and taking exercise.
These points can then be used to purchase sports equipment or clothing.
Ministers also want communities to redesign their town centres to promote more activities, such as walking and cycling, and to start up "grow-your-own veg" schemes to get residents gardening.
Other ideas include a "cycle-recycle" project designed to educate people on how to ride and look after their bikes.
Nine areas have been designated "healthy towns" - Dudley, Halifax (Calderdale), Sheffield, Thetford, Middlesbrough, Manchester, Tewkesbury, Portsmouth and Tower Hamlets in London.
Ministers emphasise that the Change4Life programme has been backed by food retailers, charities and community groups as well as the Government.
Areas can expect to see the first of the changes from next January, it is said.
Last year, the Government-commissioned Foresight report warned that unless urgent action was taken half of all Britons could be obese by 2050.
Earlier this year Johnson noted that heavily overweight schoolchildren faced dying eleven years younger than their slimmer classmates.
Announcing the new scheme, he remarked again, "Obesity is the biggest health challenge we face - a third of 11 and 12-year-olds are overweight."
Experts predict that if current trends continue the growing obesity problem could lead to rapid rises in the rates of life-threatening diseases like diabetes and cancer.