The expression, "you are what you eat," is so true. The more fatty foods you eat, the less you will see your abs, but the sooner you will see your physician due to high levels of cholesterol, or other medical issues. This is a whole other topic we will deal with later though.
A good exercise to strengthen your midsection is a pilates exercise calleded, "roll up" and "roll down,' With feet firmly planted on the ground in a double "V" position (knees bent to a level that is comfortable for you), inhale to prepare and exhale as you lift your head, shoulders, mid portion of your back and lower portion as well while looking down at our belly button (your body will be in the shape of the letter "C"). To get the obliques involved, add a twist at the top.
This is just one way to work your abdominal muscles. Have fun!