Being a rookie is the gym is exciting, but tough. You have so much potential to fulfil but the pitfalls are all to easy to fall down on. Here's three of the biggest mistakes I see beginners making (not to mention three I made for years too!).
1/ YOUR COMMUTE - Your choice of travel to and from work every day could be a great chance for you to get some calories burnt. Do you get the tube to work in London? Get off a stop early and get those steps in. Maybe you work only a couple of miles from where you live? In this case maybe cycling to and from work would be a cool way to get your daily activity up (and save some petrol money!). The other thing to consider is how stressful is your commute? If every day it's an unbearable grief then it's time to try and think around it. Being stressed for extended periods of time isn't great for you for all kinds of reasons and will make it physiologically tougher for you to lose fat.
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.