you say you are moving around a lot at work... so you are probably burning lots of calories at work... just watch what you eat - watch your calories & your sodium intake -- I think you're not suppose to have more than 600mg of sodium per meal - and most meals (especially take out) have in the thousands of mg...
i know you said you are switching to diet soda - but that has a lot of sodium in it too - if you just drink 1 or 2 a day you'll be ok... but make sure you drink LOTS of water... sodas make you retain water - which makes you bloat ... and right to your tummy, thighs... sdkfj