Kids & Cholesterol NPR's Vicky Que (KWAY) reports that our understanding of the relationship between body fat and cholesterol levels in children is expanding. Until now, scientists have believed that the percentage of body fat must decrease in order to bring down high cholesterol levels. As boys grow older and mature sexually, their muscle mass increases and fat percentages decline. So do their cholesterol levels. But, now, research shows that, as girls mature sexually, cholesterol levels drop even though body fat percentages don't decline. This new information is expected to help clinicians revise testing and treatment for young girls.