Eating 3 meals a day will reduce amount of hunger. Plus help with weight loss and if 3 meals a day won’t be in your daily meals and you eat just 1 or 2 meals a day it might cause hunger and weakness but overeating meaning eating more than 3 meals a day causes weight gain but when it comes to someone who is frequently not gaining any weight my suggestion is it is okay if you eat more the 3 meals because your body might need more and more protein to grow or other meals can be suggested such as 

Fruits, Vegetables

Half food and half veggies or fruits

Then could be sugar adjust a tiny bit so it doesn’t cause high calories just like juice or soda

But a good surgery snack would be a Yogurt and Dark chocolate, nuts.

 These are ideas that help with healthy living. So 3 meals a day in my opinion will help you with healthy living, plus a healthy metabolism.