Hi First of all I would like to thank you for your query.I have gone through your question .According to my view weight gain and weight loss depends on BMR ( basal metabolic rate) .I want to ask if you suffer from any sort of digestive issue like gas,acidity,constipation or pain in stomach.If yes then you have to keep your metabolism strong.For that you have to follow proper balanced diet,eat more alkaline foods and less acidic food,do yoga regularly ,go for a walk etc.Here I am suggesting you effective remedies for gaining weight - Have banana or banana with milk two times a day. Boil milk with few almonds,few dates and drink. Soak 5 raisins and10 almonds overnight and consume in the morning. Have more dairy products in your diet like cheese ,ghee,butter,peanut butter . If you are non vegetarian ,you can have a drink by mixing lukewarm milk with 1 egg. Eat 4-5 small meals everyday. Take a light nap after a noon meal as it helps in increasing kapha in the body. Boost up your appetite by walking daily for 30 minutes. Ayurvedic medicines which are effective for weight gain are Chyavanprash,ashwagandha,shatavari kalpa,yashtimadhu,kushmandavaleha. Practising few asanas and pranayam help in gaining weight like sarvangasan,shavasan,bhujangasan. Be positive and happy,stay away from stress also help in gaining weight. Hope you find this answer useful to you. In case you need further information,you can ask anytime. Wish you healthy and happy life. Regards Dr.Pallavi