Skinny people tend to be attention eaters, uploading photos of cake or big roast dinners to Instagram with the caption "OMG, can't believe I ate all that #fatty.' They feel like sharing their food, means sharing the calories. Attention eaters will also tend to talk more about the act of eating food, than actually doing it.
"God, you're such an attention eater. Stop showing off with all your homemade cakes and 5-course dinners."