To clarify this argument that's been going on:(sorry I'm gonna quote mine here)
Do you seriously think a piece of chocolate is going to shorten a dog's lifespan? It doesn't matter how many times you feed it candy, it only takes one piece with an ingredient toxic to rats to shorten their lifespan.
Treats are fine every now and then but you need to make sure that it is safe for the ratties, not just picking random junk foods.
A general rule is that what is okay for us is okay for them.
But okay isn't good enough on a regular basis.
In an ideal world, people would eat things only healthy for them, and would probably be healthier for longer. Junk foods lead to nutritional imbalance and obesity. A small amount of candy or chocolate for us is huge for a rat, it's like us eating a whole chocolate cake. Why do that when they are just as satisfied with plenty of healthy foods?
Sugarless cereals, occasional nuts (fat content is high there) a sweet fruit like strawberries or kiwi, meat, and even crickets (which rats LOVE) make good and mostly healthy snacks that you can feed without causing harm.
Some things we can ingest that rats CAN'T are soda, and really sticky things. They don't pass gass or burp like we do so a buildup of the carbon in sodas is potentially lethal. Overly sticky things like honey and peanut butter can cause problems too, due to rats lacking a gag reflex. It can actually clog their throats and kill them. It's like chocolate and chicken bones for dogs -- if your dog eats some chocolate or eats a chicken bone it might not die, but it COULD. So why risk it?