How to control food guilt

I have this thing called food guilt. I feel guilty if I eat a certain food that wasn't healthy, or didnt taste good. Somethings I'll eat something that was "okay" standards like a tuna sandwich or a PBnJ, but then notice someone like my sister eating something like a pizza or sushi. I have this feeling of guilt and be thinking "man, that looked so cool I wished I ate that instead". And I feel like I should be eating the same foods that my sister eats just for the sake of not looking different. How do I get over this?