A new study by Purdue University said that the girls continued to see themselves as fat even if they weren't.
The national study analyzed the weight loss and self-esteem of more than 2,000 black and white girls.
The girls were followed for a decade beginning at age 9 or 10.
The Caucasian girls were found to still have low self esteem despite weight loss and even had lower self-esteem than their average weight friends.
Meantime, black girls were found to have more positive self-esteem after the weight loss, although they tended to have a lower self-esteem to start with.
The researchers say that mental health assistance during the weight loss process could be beneficial to teen girls.
The study appears in the current issue of the Journal of Health and Social Behavior.
The U.S. Centers for Disease Control and Prevention report that some 17 percent of American children ages 2 to 19 are obese.
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