WASHINGTON, Dec. 28 (AP)  Far too many children are fat by preschool, and Hispanic youngsters are most at risk, according to research that is among the first to focus on children growing up in poverty.

One important predictor of a pudgy preschooler was whether the child was still using a bottle at the age of 3, said the study, which was published online Thursday by the American Journal of Public Health.

“These children are already disadvantaged because their families are poor, and by age 3 they are on track for a lifetime of health problems related to obesity,” said the lead researcher, Rachel Kimbro of the University of Wisconsin, Madison.

Seventeen percent of American youngsters are obese, and millions more are overweight. Dr. Kimbro focused on poverty, culling data on more than 2,000 3-year-olds from a study that tracks from birth children who were born to low-income families in 20 large American cities.