First lady Michelle Obama has become a heavyweight among public influencers since arriving in the White House two years ago. She is one of the most admired women in the world. She has become an advocate for organic gardening, women’s rights, pay equity, military families, and goodwill ambassadors. Her most important cause, however, is fighting childhood obesity. More than one-quarter of American youths are either overweight or obese. The problem is leading to steady increases in childhood diabetes, cardiovascular disease, and other ailments. Her “Let’s Move” campaign encourages children to eat better and exercise. “I want to leave something behind that we can say, ‘Because of this time that this person spent here, this thing has changed.’ And my hope is that that’s going to be in the area of childhood obesity,” the first lady said of her efforts.