How do i put on weight?

Why not gaining lbs?: A rule of thumb--to gain 1 pound eat 3000 calories more than your body normally burns. A bigger question is why are you having difficulty gaining weight? Have you explored with your doctor the possibility of undernutrition, hyperthyroidism, malabsorption and maldigestion, infection, altered GI tract function, eating disorders, inflammatory conditions, and malignancy? Pursue evaluation please.

Eat healthy foods: high in calories. Eat 6 meals /day. Work on strength training to build large muscle groups. Work out w heavier weights w fewer repetitions. Sleep at least 8 - 9 hrs/night. Hydrate well w water. Foods to help w weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, protein shakes & bars, lean meats, poultry, fish & smoothies.