Hello, I have taken every test you can dish out at me, and my bf% is always 7.5 or less. I work my abs Monday, Wednesday and Friday after lifting weights. I lift weights 5 days a week. My BMI is 21, I'm 19, 5'8" 140lbs 129.5lbs of lean body mass, I swim everyday, take multivitamin supplements, I eat healthy (green veggies, lean red meat, chicken, and rice) when I work my abs I use weight increments and do 3-5 sets of sit-ups on an inclined bench, 3-5 sets of reverse crunches, 3-5 sets of knee raises and 3-5 sets of the ab cruncher machine. I've been working my abs for five years now, and just in the past year started using weight incremenants. My stomach still sticks out like a balloon when I don't flex. HELP!