Change the way you live, and your body will follow. Then again, great athletes are born, not made. If you have the knowledge, genetics, and motivation, then you can win. But two out of three ain't bad.
The ideal is small, frequent meals low in fat (20% of calories or less from fat), low in simple sugars (or high in complex carbohydrates), and, preferably, high in [micro]nutrients. The majority of calories are consumed in the first part of the day, with no food consumed preferably within 3 hours of sleep. It'd be nice to eat about six times a day, with meals 1-3 hours apart.
I drink a lot of water throughout the day, especially prior to meals (as an appetite suppressant), when taking thermogenics (which have a diuretic effect), and during workouts (always replace lost water!). It is nearly impossible to overdose on water. Ice water is preferred. However, I restrict water intake immediately following meals (to facilitate digestion), and before bedtime (so as to not interrupt sleep).
Given certain constraints, it comes out like this.
500 calories, high in fiber and complex carbohydrates
This is the perfect time for something like oatmeal or grits.
300 calories, mostly protein
Lean meats, egg whites (17 calories for each large egg), etc.
300 calories, mostly protein
Canned tuna is inexpensive.
200 to 300 calories, simple sugars
Gatorade, Powerade, or something similar, after workout(s)
100 calories, mostly protein
A protein shake, egg whites, or canned tuna, etc.
It is extremely important to sleep at the same time each night for at least six, preferably, eight uninterrupted, consecutive hours.
Increasing or maintaining lean body mass is important in all weight/fat loss plans, and doing High Intensity Training exclusively is one of the most effective, and efficient, ways of accomplishing this.
Simply being more active on a daily basis, aka 'in your habits,' can and will improve your body composition in the long term. As little as 10 minutes of moderate activity can be beneficial. Repeated two to three times daily it is quite ideal. Warm baths can also be of benefit.
On the more extreme side of things, in other words or what I do... 2-3 hours of aerobic exercise done twice daily does result in significant weight loss, including not insignificant losses in lean body mass.
This is something I would prefer to do if I had more time to lose weight.
It usually looks more like this, performed on Fridays, simply in order to maintain as much lean body mass as possible.