Whilst what goes on in the kitchen does have a big impact on what state your mid section is in, it's not truly where you're abs are built.
Your abs are like any other muscle group in the sense they can contract and stretch, they can get DOMS and they can become stronger/grow.
Assuming you have average genetics, the key thing where carving out a sixpack is concerned is two things:
1. YOU NEED LOW ENOUGH BODY FAT - This is only to happen by burning more calories than you take in, to then get into a position where your body can utilise some of that excess belly fat as fuel.
2. YOU NEED TO BUILD A STRONG MID SECTION - If you want a well defined sixpack your abdominal wall and deeper abdominal muscles need to be strong and conditioned. Crunches and sit ups aren't the answer. Again, like many good answers to common gym questions, the answer is to get stronger and progress on your big compound lifts that heavily tax your core strength and stability. Deadlift and squat variations are fantastic for this.
So yes, the kitchen does have a huge impact on you showing off a lean torso, but you can't show off well what hasn't been built well.