The easiest way to gain weight is to consume more calories than your body needs. Assuming you want to gain muscle, the best way is to incorporate resistance training into your life. Your body will respond to progressive exercise by increasing muscle size. Continue to change your workouts perhaps by enlisting the help of a trainer to provide constant stimulus to the muscle.
In addition, your diet needs to supply adequate nutrients to support muscle growth and extra calories each day to fuel this growth. The easiest way to consume adequate nutrients is to eat a balanced diet and take a multivitamin daily. Supplements may be useful to promote an increased calorie intake, such as meal replacements for those who have a difficult time ingesting adequate calories. And always use a pre and post exercise formula on training days. Sign up for the dotFIT Me Program
if you'd like a complete customized program (exercise, diet, supplementation, etc.). Once you’re enrolled, choose Muscle Gain as your goal.