My height is 5'4" my weight is 110 lbs my ideal weight is 125lbs i've always been thin could eat anything and not gain a pound but i have been trying to gain weight but just cant keep it what can i do to make the process easier ?

Dr. can check 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,...