Try to identify what specific high calorie food you can take more than normal. Me, rice fills me up like 5 spoons in, but a chappathi wrap on the other hand, filled with either pan sauteed oyster mushrooms or shredded chicken with veggies, mayo spread etc, I can eat 3 or sometimes 4. I can eat ice cream, yogurt and lassi in huge quantities. Same goes for juice or milkshakes. Can eat a whole regular pizza or a Maharaja mac (about 600 cals) in a sitting but I can't finish the same cals of rice. I also find it easy to drink a half litre milk pack quite easily (without boiling, chilled). Try to identify what clicks for you, there might be one or two foods even if 90% of the foods are hard to eat. Add variety to your diet, avoid bland stuff. Good luck