Go to the grocery store after eating and not before.
When you go to a store to shop for groceries, it is always best to do it after grabbing a snack, or eating lunch.
This is because shopping in groceries when you are hungry can make you purchase food items, which you really do not need.
In most cases, when you get home from shopping and eat lunch, you would realize later on that you have gone over your budget, for taking in too many food items.