Ill add a differnt prespective to all of this.Good for you on deciding to live a little better and try to improve yourself for the army and yourself.Although your diet on courses usually ends up what quickest to down the hatch,after graduation and posting to your unit you can be more selective on what you eat to improve your performance.
I can't say a diet of beer and chips is the greatest thing,it should establish a mindset for yourself that a large percent of the army are not fitness nuts.So going on a BMQ you shouldnt worry too much. Although improving your fitness WILL IMPROVE your ability to deal with stress,climate change,and physical demands placed on you by the big green machine.
Make your average day difficult physically,and suddenly the physical demands of the army seem mundane.
(sorry for any spelling grammer errors,im on a dial up connection in the boonies and spell check would take 20 minutes.)
keep up the good work.