First off I'm going to give you my body specs.
height: 5' 10"
BMI: 17.5
weight:123
fat %: unknown at least below 10% though


Ok now back to the question I am wondering why I can't see my six pack. I can see a clearly toned and defined stomach when I do not flex. And when I flex I have a small but very visible 4 pack (upper abs.) and everyone tells me I am very skinny and have hardly any fat but I don't understand why I cannot see my six pack because everything I have read says that if you have a low body fat percentage that your six pack will defiantly show. So can somebody please explain to me why I cannot see them. Is it because lack of muscle or to much fat? Serious answers only please!!!!