What is wrong with my family member...Dramatically overeating a particular food?

One of my family members has recently(within the past 2 months) began consuming ridiculous amounts of the same food. They are fruit popsicles loaded with sugar. He goes out and buys 4-5 boxes at a time and consumes them morning, noon, and night. It has even gotten to the point where he is hiding empty boxes of them around until garbage day. I am really worried and feel like he needs some self control. Is this considered to be a mental illness? And how do you correct it?