With my wording, I can see how it seems lacking, but I assure you it is not to the extent it seems. They get beans (though not too much, I share a room with these girls!), slices of apple, grapes, watermelon and many other fruits and vegetables often, yogurt drops as treats, actual yogurt, cereal, cooked potato... Many, if not all, we've seen in rat diets listed on the web, and we try to do it in proportional amounts, especially as sites suggest. We make sure not to give them too much protein--the whey powder was more a possibility for adding to (as above) a sort of granola bar that could be given as part of a new diet or an occasional treat. I assure you I research things well, especially a pet. This includes goldfish.
I DO agree that their diet isn't the best, which is why I plan on revamping it. (Although I doubt it will ever be ideal, since my mother and sister spoil them with anything they have that does not fall on the forbidden list...) I've only owned rats for about 2 and a half months now, so I still have much to learn. We are actually planning to switch to blocks and formulate a diet around that, but last time we were at the petstore all they had were hamster food blocks, which I'm not really willing to incorporate into their diet... Hopefully next time they'll have some, or else we'll either search elsewhere or simply make a complete diet from scratch based off "recipes" on the web.
I apologize for the very lengthy reply, I just didn't want to come off as an ignorant owner, as ignorance, especially in animal owners, is something I abhor.