Depends on your body type (weight,height), your age, metabolism etc. All the suggestions so far are good but find out what works best for you by experimenting with these recommendations, then keeping track of your progress over time. so try portions of these various replies, make a list of say 6 food groups/examples that you'll eat one week, then 6 more the next week, and so on for 4 weeks......and keep track of your weight changes, how you feel through the day physically and mentally. then adjust accordingly.
Of course this doesn't account for your exercise regimen. bottom line keep track of your habits daily, note the results, and make the adjustments