I'm 27 yrs old 5"8 & anemic i want to gain weight i weigh 130 to 140 every now and then how can i gain weight naturally? & what's the average weight

145 should be fine: 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, ....