I came from parents with no junk in the trunk. So it was inevitable that despite years of step aerobics and running (in addition to weight lifting) that I too would have nothing back there. I hated all that sagging material in the back of my pants. Recently, one "kind" friend said to me "You REALLY have no ass!" And sadly she's right.  But these trunks have changed that. No one has said a word, not sure they have even noticed. But I can tell you that the padding fills up the backseat material of my pants nicely without looking like a shelf to place drinks. I think the look is very natural and has boosted my confidence (like when I got braces as a kid to correct a crooked smile). I  wear size 30 underwear and got the small; it was  bit tight though it really pushes out your junk in the front if you like that sort of thing. The second go round I bought medium and they are more comfortable for me.