In terms of maintaining/building muscle mass and burning fat I can give you a list of 12 healthy eating foods:

01. Almonds and other nuts
02. Beans and legumes (especially lentils, kidney, chickpeas, soy and black)
03. Spinach and other green leafy vegetables
04. Dairy (low or no-fat, and not loaded with sugar such as ice cream)
05. Instant oatmeal (unsweetened)
06. Eggs
07. Turkey and lean meat
08. Natural (unsweetened) peanutbutter
09. Olive oil
10. Whole grain bread/pasta
11. Whey protein (from ricotta cheese or from whey powder)
12. Raspberries

All these foods have a low glycemic index, and also have "good fat", omega 3's, are high in fiber and/or are rich in quality protein. They offer the most nutrition that your body can utilize efficiently without excess fat, sugar and artificial crap that your body doesn't need.