Hey there! I recommend eating before stepping out of your home/room because when you go out hungry, you come back having over-eaten.
When we are hungry, our mind stops thinking rationally about food and we grab anything we can get to eat. Mostly the hunger makes us crave for sugary or salty foods both of which are very bad for our health.
You cannot control yourself when you are at McD and you have money to buy the big Mac. YOU WILL EAT IT. Hence, never go hungry. Always eat something before going out. BONUS: you will save money!