Eat in a caloric surplus, rinse, repeat and you will gain muscle/size.
Go look on martin's site, there is human evidence of it being done.
If you fill up fast alter your sources and what you eat at your meals, Use less fiber, but still make sure you are getting adequate micronutrients from fruits/veggies and a variety of foods. I can easily take down 3-4k calories in a 6-8 hour window. Just got again be smart with your food and choices.
Eat your calories in your window, Pretty simple.. NO other way around it.
Workout intensity is based off you and your mental aspect towards pushing yourself. You should always be training intense and always training heavy regardless of your goal
The key factor = Caloric Surplus and consistency.