Complex sentence: Overall, the program was highly successful in bringing down the obesity rate of schoolchildren from 14% to 9.8% by 2002, but it came at a psychological cost of participants being stigmatized and in some cases, reportedly diagnosed with eating disorders.
Split into simpler sentences: Overall, the program was successful in reducing the obesity rate amongst schoolchildren from 14% to 9.8% by 2002. However, it came at a psychological cost of participants being stigmatized and in some cases, reportedly diagnosed with eating disorders.