I once heard a story that certain diet soft drinks or diet foods contained a chemical or chemicals that made you hungry. There are some levels of sodium in diet soft drinks, for example, but I have found no research which backs this claim. Although instead of buying a big bag of chips a big chocolate bar, and a large diet soft drink (to wash it all down) when you drop into the convenience store, perhaps think about a very mall bag of chips and a small diet soft drink?