Cheese. Hard-boiled eggs you cooked the day before. Cold roast beef. Precooked shrimp. Tuna. Canned ham. Use your imagination. The NO list is much shorter than the YES list:
NO!
Flour
Sugar
Any combination of the two
Potatoes, yams, peas, corn, or fruit, especially in the early stages of the diet.
YES!
Anything that isn't on the above list.