Food is key.
I remind myself every time I eat in a restaurant on travel that this is NOT a special occasion, and that there is no need to have a full meal from soup to nuts.
Soup and a salad; one or two appetizers; a salad with added protein - these are all full meals. No need for bread, dessert, or drinks full of calories. If you're eating every meal in a restaurant, there should be no need for "treats".