Drink a shake for breakfast, and a cup of coffee or tea with Splenda. Have a mid-morning snack. I usually have a low-fat graham cracker, or a yogurt.
For lunch, eat a real meal, but pay attention to fat content. Just use common sense. If you go to Subway, don't order the meatball grinder. However, you can order the grilled chicken breast and have them put marinara on it. You can also have low-fat chips. Most other fast food is out. Salads with low-fat dressings, chicken, fish, rice, veggies are all great - just watch the fat and how the food is prepared (i.e. grilled over fried).