One thing all overweight kids have in common

Overweight children have been found to have something in common besides extra padding around the middle: they all seem to share high levels of a certain protein (apoB48) found in intestinal cholesterol. ApoB48 has been proven as a risk factor for adults for developing cardiovascular disease, and although the children aren't currently considered at risk for CVD they will become so as they age unless their apoB48 levels drop.

Whether it's due to diet, genetics, or a combination of both, why certain people have higher levels of this protein isn't yet understood. But how much fat and what kind a person has does seem to have a major impact.