Low body fat is not the only factor in having thick veins popping.
Increasing RBC, as well as vasoldilation will give you significant increases in vascularity that are permanent for a long time. You ever see a guy with a freaking 1/4" cable running down his bicep? It's because of vasodilation. Increases in lean body mass will also have in increase in the diameter of your veins(which is what vasodilation is).