What is the developmental pattern of obese individuals and what could explain this pattern?

Why is obesity such a problem in the United States? What are some societal changes that potentially account for this epidemic-like change?
What are the long-term consequences of childhood obesity?
What is the developmental pattern of obese individuals and what could explain this pattern?
What are some social policies implemented at either the local, state, or federal level to reduce the number of obese children? Have these interventions been successful? Why or why not?