Surprisingly enough, your stomach does not suddenly grow when you go to a restaurant. Nor does your metabolism speed up. This means… you need not eat more at a restaurant than you do at home. So, picture what your plate would look like if you were at home and figure out a way to eat only that amount at the restaurant.
The problem is that most people have a hard time eating only what they need when, in fact, they have much more than they need right in front of them. So, you might want to ask the waitor to immediately put half the dish in a container to take home, before you’ve even started eating!
Always try to remember what it is you really want. Is it to enjoy a certain food for a few seconds or to live and long, happy, vibrant life until 120?