Over one-third of adults and one-sixth of youth in the United States have obesity. After decades of worsening, the trend has stabilized in the past few years. However, the US obesity rate is still among the highest in the world and carries a price tag of $117 billion a year in medical expenses. Americans’ diets are slowly improving, but new health initiatives remain crucial. New studies focused on youth, a group especially at risk, are looking at the effectiveness and cost of different interventions and the impact of certain foods over time.