Foods That Cause Blood Sugar to Fluctuate So, what I call all the white stuff, so these are foods that are quickly turned into sugar in our body: bread, pasta, cereal, white rice, white potatoes, and the things like milk because there is a lot of sugars that are very rapidly broken down and absorbed in the body. And you get rapid rise in the blood sugar, and insulin follows, and then two hours later you come plummeting down so you create an up-and-down effect all the time in the blood sugars that really can affect depression, anxiety, irritability, many, many different symptoms.