How do i gain weight the healthy way?

Want more mass?: If one is truly underweight (based on height, family background, and body type), a doctor 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....