How can i fatten my self i'm 21years old i weigh 48.5 kg and my tall is 158cm i have had ocd for 7 years and i think too much of silly things?

See doctor first...: If one is truly underweight (based on height, family background, and body type), a Dr. can evaluate for a hormonal, digestive, or other disorder. If no medical cause is found, then one can add weight by eating more calories of nutritious foods, while also doing weight-training to increase muscle. Proteins: egg white, chicken breast, salmon, ... Better fats: olive oil, peanuts, almonds, tofu, ....