Peanut butter, yogurt with protein powder mixed in, almonds, canned chicken instead of tuna, eggs of all sorts (hard-boiled and ready...etc.), dried fish, meat, salsa mixed with any of the above, sugar-free jello, Atkins chocolate dipped in peanut butter (oops, just gave away a secret)...You can even resort to a low-carb nutrition bar with some sort of "extra fat" source on the side.
Just don't try to cut out what makes up the "balance".