I dont know the techincal ins and outs of dieting, but i know for sure that you cant turn fat into muscle. Thats a preconception that has no truth in it at all. Someone here will be able to explain to you about calorie intake, expenditure etc. All i do is make sure i eat enough carbs to give me the energy i need to work out, eat alot of protein [especially after workouts] (chicken and fish mainly), always some vegetables with main meals, and a little fat (as long as its not saturated fat!) [i usually opt for peanut butter]
As far as i know, your body turns excess calories into either muscle or fat, depending on whether you work hard enough (someone please clarify this for me?), turns sugars into fat, fats into fat (duh!) and carbs into fat (which have some sort of glycogen (sugar) release in the bloodstream. Some release this energy over short periods of time, others over long periods of time)
Your body uses protein to repair and build muscle, so alot of protein is essential for building muscle mass. If youre eating beef, make sure its lean beef. Its no good wolfing down the protein if it comes with fat too
EDIT: Heres a copy of my diet plan from another thread. I eat this to reduce body fat and
maintain muscle mass, so you'd need something slightly different i'd assume. I'm also 155lb so you'd need to adjust consumption to your target weight.
Breakfast: 2 slices wholemeal/multigrain toast with Humous or peanut butter.
Mid morning snack: Apple and banana or mug of soup and 1 slice of whoemeal/multigrain bread.
Lunch: Tuna and light mayo sandwich on wholemeal/multigrain bread and a banana or steamed chicken breast on whoemeal/multigrain bread and a banana.
Mid afternnon snack: Apple and banana or mug of soup and 1 slice of whoemeal/multigrain bread (whichever i didnt have mid morning)
Evening meal: Steamed chicken breast with potatoes and vegetables (usually spinach/broccoli/cauliflower) or Steamed salmon/tuna fillet with potatoes and veg.
Pre-sleep snack: 1 slice wholemeal/multigrain toast with cottage cheese.
5-6 meals a day will help speed up your metabolism, and as your body is being fed at regular intervals, it will be less likely to store fat (which it does when you eat big meals at longer intervals. This is because the body has to save some of that energy incase the next meal doesnt arrive, so it has something to feed off)
Thats as far as my knowledge goes, its not scientific at all, its simple laymans terms, but i think its pretty accurate.