Many people who are struggling to gain weight do not eat enough protein. You need to consume a large amount of protein each day in order to gain weight. Your body will require hundreds of additional calories each day along with a strength-training regimen. Your body needs fuel to build muscle and add bulk. Make sure you consume enough extra calories each day. Your body is resistant to changing the status quo, so you'll have to consistently consume large amounts of protein, fats, and carbs if you want to gain weight. The proper diet is crucial to teaching your body how to gain weight.
For most people, your metabolism will naturally slow down as you get older. This is why people gain weight as they age, but in some people this does not happen. They have a very difficult time even as they get older. These are called "hardgainers". Online you find many young men who are hardgainers, but believe it or not, there are also women who have this problem as well and can be called hardgainers!
One of the most effective ways to gain weight is to train with weights. Concentrate on free weights and exercises that work the large muscle groups. If you have struggled to gain weight with little or no success, you most likely have a fast metabolism. This will require intense workouts done for short periods of time, several days per week.
If you follow some simple tips on how to gain weight, you'll increase your chances of success in reaching your goals.