I can tell after just a few days of drinking milk. Even by the end of the day if I have had a few glasses of milk, it will start to patrude. Another thing you can try, is the stomach vacum which was sort of stated earlier. It works the intercorsole ab muscles which are responsable for keeping your stomach from busting through and allowing ur abs to be sucked in. The body builders back in the day used to love doing that which is why although they had great amounts of mass, their stomachs were almost cartoonish small in comparison. Start out on all fours (which is the easiest way to contract) blow out all the air in your lungs and suck your belly button into your spine. hold it as long as you can. over time, you will be able to do it wiht blowing out less and less air. once you can hold it easily for over a minute for ten times, when you can do that, try to do it sitting, once that becomes easy, try it standing. once you have masterd that, do that 10-15 times a day eod and see if it does not help pull your stomach in nice and tight