To gain weight naturally could mean a number of things when you look at the question from a weight trainer's point of view. Obviously the most important part about gaining any good quality weight (i.e. Muscle) is the food that you eat and what you and when you eat.
Probably the most important part of gaining weight naturally is eating at least every three hours. To do this you need to plan ahead and to make sure that you are not just eating junk foods on impulse but to rather prepare your meal and/or snacks ahead of time.
You need to be a bit creative if you are trying to put on weight naturally because you need to add things like peanuts and avocadoes to your regular diet/snacks/meals. Things like dried fruit and smoothies are going to help you pick up weight a lot faster than junk food.
It is important to work out your calories that you need and the calories that you consume. A good target is 500 calories more than you are burning but in order to do this you need to know how many calories you are burning. You can do this easily by going online and getting a simple formula that will get you the approximate value of the calories you are burning.
If you eat 500 calories more than you are burning you will gain a pound every week. But you don't just want to put on a pound of fat every week that is not what your objective is. In order to put on good quality weight you need to do regular progressive resistance training with weights.
If you are new to training with weights in order to pick up weight then you are lucky because the first year of training you will pick up more muscle than any other time in your weight training career. The reason is simply because you do not have any serious muscle to speak of so any muscle you put on is going to make a big difference to your weight.
Muscle is two and a half times heavier than fat so you really do not have to put on a lot of muscle in order to see the scale show higher values every time you stand on it. Just make sure that you are using the correct technique and that you continue to get stronger every week.
For more weight gain information go to Weight Gain Workout And Diet Plan