If you ever have the opportunity to eat Chinese food in Beijing, don't miss out on the Beijing Roast Duck (what used to be called Peking Duck). It'll be expensive, but it's a taste treat; you'll get strips of mostly duck skin served with plum sauce, strips of spring onion, and light crepes.
Restaurant-style Chinese food can be rich in calories and fat; if that's an issue you're worried about, focus on light foods like steamed vegetable dumplings, steamed shrimp and broccoli, Moo Goo Gai Pan, chicken and bean sprouts, and steamed vegetables.