Washington, D.C. ? Far too many kids are fat by preschool, and Hispanic youngsters are most at risk, says new research that’s among the first to focus on children growing up in poverty.

The study couldn’t explain the disparity: White, black and Hispanic youngsters alike watched a lot of TV, and researchers spotted no other huge differences.

But one important predictor of a pudgy preschooler was whether the child was still using a bottle at the stunning age of 3, concluded the study published online Thursday by the American Journal of Public Health.

Some 17 percent of U.S. youngsters are obese, and millions more are overweight. Obesity can lead to diabetes, high blood pressure and cholesterol, sleep problems and other disorders. Overweight preschoolers have a five times higher risk of being fat at age 12 than do lean preschoolers, scientists reported last fall.