I agree that much of it is diet:make sure to eat enough calories to fuel your activities, but focus on nutritionally-dense foods, eliminating high fructose corn syrup/sweetener and (partially-) hydrogenated oils from your diet if you are currently using them.
Also, try doing full-body weight workouts, weight/cardio circuits, and not doing excessive cardio.
For example:'
Day 1: PLB (or lower body workout)
Day 2: moderate cardio
Day 3: PUB (or other upper body workout)
Day 4: moderate cardio
Day 5: full-body weight workout (like PH/ME/SS/PP)
Day 6: off/stretch
Day 7: off/stretch
Try that for 3 weeks and see if you are getting the results you want. If not, then change it up.