Hello, since you are young (18 yrs old as mentioned by you) , your metabolism is high and that's why probably you are able to digest everything that you eat and not gaining much of weight. For feeling energetic, include foods like milk, paneer or cheese sandwiches, aloo parathas, milkshakes, fruits like mango, chickoo, bananas, grapes, muskmelon, dry fruits like kaju, kismis, almonds, add one chapati more to your lunch and dinner, add rice to your meals. We need to understand in more details what your daily food intake is so that we can help you in a better way. Visit www.dietclinic.in.