I have gotten significantly leaner since eating alot of squash and potato as opposed to just leaves and the like. Basically starch.
I'm not sure i'd ever eat what chocotaco is eating(not sure what half that stuff actually is), but carbs have definitely helped me lean out. As far as abs go, i find crunches to be in the same category as all isolation work- Pointless. The best anterior/interior core work is lifting heavy overhead, squats, deadlifts, (any O'lift aswell actually), and BW things such as dips/chins and so on. Plus KB swings. basically, anything that means the whole body is required to do the movement!
I also do pull ups on a set of gymnastic rings with my knees raised- this hurts. But essentially, i will only perform movements that have a purpose. Crunches don't. If you do these things above ^^ and have a clean diet, visible abs will come. Whether that means less or more carbs is entirely dependant on your disposition/metabolism/genes.