Just because you’ve had one doesn’t mean your diet is ‘ruined’ and you should finish the rest of the pack!
The first few Pringles, spoonfuls of Ben & Jerry’s, slice of Domino’s Pizza have likely done nothing to compromise your diet. It’s the ‘fuck it my diet is ruined might as well finish it’ mentality that’s done the damage!
These foods are not bad they are just high in calories and have little nutrient content so they should only be a small part of your calorie allowance (20%).
Your diet should be sustainable but there has to be some control/restriction. When you say ‘fuck it I’m finishing the tub, carton, box you have lost control.
After you’ve had your taste of the delicious treat, tell yourself that it’s ok and you are still on track, then put it away. If you have a problem with these types of foods where you struggle to control yourself around them keep them out of your house.