it is dangerous to equate food to love, and natural for mother's or grandmother's to show their love by food, especially when they grew up in lean times. he is just doing the same. weight loss aside, this is not healthy behavior period. thankfully his heart is in the right place, so perhaps sitting him down and explaining what this means to you? maybe suggest an omelette rather than donuts?
I am not a shrink, but question to consider, is he worried you are doing this to attract someone else?