People often suggest not to go to the supermarket when hungry. But I've found that it works the other way too: if I go shopping right after a large lunch, little of the food I see ‘inspires’ me, so I buy way too little and I'll find myself having to go back to the supermarket way sooner than I had planned

Perhaps if you go to the supermarket when you really don't feel like going to the supermarket you will end up with decisions biased towards not needing to go to the supermarket. ie. Buying lots of food.