Hehe, I know what you mean
As you've worked out, eating big meals and having toned stomach muscles does not a flat stomach make. Typical biker-esque physique, useful for belly-bashing and whatnot.
Situps.
Lie on your back. Fix your feet under a bench or functionally similar device. Feet a little distance from buttocks. Cross your arms so that your palms are on opposite shoulders. Raise your upper body until your elbows touch your knees. Repeat.
Stomach Crunches.
What the ladies do. Lie on your back, feet fixed as above. Touch your fingertips to the back of your ears. Keeping your back straight, raise your torso off the ground a couple of inches. Hold for 5 seconds, rest a breath in, exhale, repeat.
Leg Raises.
Lie flat on your back, arms at your side, feet together. Lift both legs off the ground a couple of inches. Hold for 10 seconds. Rest for 5 seconds, repeat.
Swimming is obviously a great option. Consider generally working on your posture; stomach in, shoulders back and down, chest out, head up.
Don't go having those huge meals that stretch your insides to jiggery and wash it down with ten pints, especially not at 11pm!
It's a funny one, as whether the stomach hangs in or out can affect your balance when fencing. And you obviously don't want to be consciously pulling your belly in when fencing as it'll distract you and even worse, create tension in the upper body. So that's where this toning business comes in, so the body does it naturally.
Anyway, best of luck. Foilists are the sexy ones, remember
