So I have a huge problem gaining weight because of genetics and all that so what has worked for me is eating normal meal portions at least ever 3 hours from when I wake up. snacking is optional but I find snacking doesnt necessarily lead to healthy weight. I also don't drink coke, I stick to diet if I have it and same goes for ant other fizzy drinks. But I still stick with water mostly. it doesn't work the quickest but as long as your meals are the same portions as before and your eating those meals within the 3 hours daily you should see a weight increase