Researchers examined the conditions of physical activity and physical inactivity among the children, and the impact on the children's amount of adipose tissue and endurance fitness.
Babies have lots of brown adipose tissue, or brown fat, so called because of its color.
say they have identified a fat known as brown adipose tissue in adults and discovered that it plays a role in how the body expends energy.
Miss Velasquez, from Austin, Texas, was born without adipose tissue - meaning she has no body fat and, despite eating up to 60 small meals a day, remains at a delicate 4.
