Include lots of protein too for your muscles
Maybe have 2 protein shakes a day AS WELL as your normal meals. Eat 5 times a day still so you're metabolism is still good
Have a hot glass of milk before bed at night (full fat) it will help you sleep too.
Add a tablespoon of olive oil to your meals.
Full fat milk and yoghurt
But keep having fruits and veggies of course
You MUST get 5 kilos, otherwise...?
Any food that is high in carbohydrates, proteins or fats can give you a lot of Calories. Whole grain bread, fish and nuts are all high in calories and often mentioned as healthy foods. Physical activity during higher calorie intake can help you to get more muscle mass instead of belly fat.
Chocolate, cakes, fruit juices can quickly add to belly fat...