Both....or you could lay on the floor with a medicine ball, but the extend your hands straight out with the medicine ball in your hand (should look like a straight like) and do flutter kicks....will have you sore as hell...
I eat whatever and just workout....I have cut down on junk foods and I eat tuna after I'm done working out...I also drink alot of water but as far as diet it depends on what you tryna accomplish...are you tryna lose weight or just tone...
Yeah you gotta get the diet right. I used to crunch 250 pounds on an ab machine. My abs got big a strong, but didn't show like I wanted them to because I was still eating to much junk food.
WallH basically said it. Abs won't show if you have extra layers of fat blocking them. So don't even worry about them like that until your body gets to the point where that extra fat is burned. You do that by eating better and doing more low-intensity cardio and weightlifting
It really dont matter which one you do. IT you have a layer of fat over stomach you wont be able to see your abs. (atleast not all.) I run ever day and use the ab roller