Wife secretly eats chocolate

My wife eats chocolate in secret. She eats about one big bar a night, when I pop to the pub for an hour. I accidently found where she hides the chocolate yesterday and was somewhat shocked. Its really weird having a wife of 10 years, who hides her chocolate. She is aware that she eats a lot of chocolate. I cant see why she cant eat half a large bar or one normal bar. She says its like me having a bottle of wine and only being allowed one glass. I have commented on a weight recently (i was very sensitive!). She recently joined a gym and I find big bars of chocolate in hiding. We havent had sex for an embarrassingly long time. I think she does it in secret because I dont approve how much she eats. It wouldnt bother me if it was a normal bar size. she often feels guilty afterwards and doesnt really enjoy eating large quantities, its just a bad habit. What do I do - its like living with a secretive person (gambler etc).