The nation is celebrating a new study reporting that the obesity rate for children ages 2 to 5 has plummeted over the last decade. But one of the sadder parts of the study released Wednesday was that the U.S. obesity rate is a reflection of the nation's racial divide: Blacks and Hispanics suffer much higher levels of obesity compared with whites.

As you can see in the chart above, obesity rates among babies are fairly similar across racial lines. But the disparities rapidly emerge. A black child age 2 to 5 is more than three times as likely to be obese as a white child that age. Hispanic children in that age group are nearly five times as likely to be obese.

Put another way: We're celebrating the fact that for all kids ages 2 to 5 childhood obesity has declined from 13.9 percent to 8.4 percent over 10 years. Yet, 11.3 percent of black children ages 2 to 5 and 16.7 percent of Hispanic children that age are obese. Just 3.5 percent of white children ages 2 to 5 are obese.

Why the disparity? Income certainly plays a central role, though this study didn't look at that factor. Researchers have other ideas, including the fact that black and Hispanic children eat solid foods earlier than doctors recommend, watch more television, have a higher intake of sugar-sweetened and fast foods and have mothers who face higher levels of maternal depression. It's not a hopeless situation -- breastfeeding by black and Hispanic children has increased, and government programs are fighting the disparity -- but the gaps are vast.

As you can see in the chart below, the disparity narrows but persists over time. It makes sense: As black and Hispanic children enter the school system, their nutrition should improve and their physical activity should increase. The challenges of American education notwithstanding, schools still tend to have a harmonizing effect.

After high school, the racial disparities widen again, reflecting the harsher economic conditions faced by blacks and Hispanics relative to whites.