Hello there..... Have six meals in a day – three big meals and three small. Breakfast, lunch, and dinner should be heavy and calorie-rich. A heavy dinner adds weight to your body as your metabolism is not as active when you sleep as compared to when you are awake.... Only calories won’t add to your body weight,include the right amount of proteins to your diet. Remember , if you want to put on weight and look fit, you need to build muscles not flab. Eat - Eggs, lean meat, fish, pulses, sprouts, and dairy products that rich sources of proteins. Fish such as tuna and mackerel are rich in oil and are one of the best ways to increase weight.