I agree with bill. In the lab, with UW weighing, BIA, and BodPod (air displacement) lean/athletic types always get screwy values. I consistentily turn out at 14% in the bod pod and -5% on the BIA. Lean guys with little muscle end up unreadable with Bod Pod and with high values on BIA. In the end, skinfold calipers and an “athlete” equation to plug it into seems the best method for guys with muscle and not too much body fat.