I just read that the Japanese have a saying that you should eat 30 different things every day. It helps make sure you get a wide variety of nutrients. Just make sure the portions are tiny. Think of a bento box, lots of little treats.
To get over the plateau and keep your metabolism reved up.
its good to do low calories for 5 days and then 2 days a week increase your calorie intake by like 500 and then decrease it on your other days, so never let your metabolism adjust! This is a secret athletes use all the time!