Hello Sumit, You need about 1710 calories to maintain your current weight and at least 2710 calories of a high protein, moderate carbohydrate and 30% fat diet inclusive of omega 3 fatty acids such as found in fatty fish, virgin olive oil, supplements. I am assuming you are male and want to weigh around 70 kg?I am thinking that perhaps you think you are eating well, but are not getting the calories and nutrients you need. Some people have a naturally higher metabolism and I wonder if the doctor has checked your thyroid. If your thyroid is normal, I suggest a referral to a nutritionist for a complete assessment and a high calorie, high protein diet with appropriate supplementation (if needed). Do not rely on medicine to change your body type,use good nutrition, strength training and I recommend a referral to a personal nutritionist. Good Luck! Kathryn Shattler, MS,RDN, your online nutritionist.