 Clearly that woman (either, you have a GF problem and a MIL problem) doesn't have any regard for your health or well being.  

Edit: Yes, it's completely a control thing.  We decided to become more observant, and somehow it's a personal affront to them. They no longer have control over one aspect of our diets and it kills them. These narcs seem to have a common list of things they *need* control over: food, hair, clothes, religion, and who goes where for the holidays.