Underweight? See how to add pounds healthfully. Consume more calories than your body expends. If you aren't gaining weight, though, you aren't consuming enough.
Consume More Meals:
Smaller meals are more convenient to consume than larger ones. Increase your daily calorie intake by 3–4 times. Get up earlier, have breakfast, and then consume three to four additional meals throughout the day.
Consume Caloric Dense Foods:
Foods that are high in carbohydrates and/or fats have more calories per serving. Consume a lot of pasta and rice.
Eat More Protein
Include a complete supply of protein in each meal, such as meat, poultry, fish, eggs, and so on.
Go with Liquid
Blended meals are easier to digest than solid food. To produce weight gainer smoothies, blend together oats, milk, banana, peanut butter, and whey protein in a blender.
Increase the frequency of your meals
You may feel fuller sooner if you're underweight. Instead of two or three substantial meals throughout the day, eat five to six smaller meals.
Exercise
Strength exercise, in particular, can help you acquire weight by strengthening your muscles. Exercising can also help you eat more.
The more you exercise, the more calories you burn, and hence the more calories you must consume to achieve a caloric surplus. I had trained until I got the perfect height and weight (From 120 lbs 5'10 to 158 lbs 5'10 in 3 months) at Iron Orr Fitness gym in San Diego, CA.