There are four types of metabolism:

Endomorph metabolism is slower and means a more massive body which tends to become overweight.The person who has this type of metabolism needs fewer calories; the recovery program which follows the practice is also longer.The person who has an endomorph metabolism has more endurance to effort than people with other types of metabolism when trying to build muscles. The ectomorph metabolism is very fast. The person rapidly recovers after practice if he is eating healthy but has great difficulties to gain weight. Fat deposits are simply smaller and it needs more calories than other types of metabolism. If the calories are not sufficient the muscular mass drops down extremely fast. To gain muscular mass the ectomorph person needs large amounts of food high in calories.The mezomorph metabolism- This is a normal metabolism, a balance between endomorph and ectomorph. People with mezomorph metabolism are more massive and stronger; they also have better health than the other two metabolisms and have no tendency to gain weight. 

The mezomorph metabolism needs fewer calories to maintain the muscular tissue healthy and the process of destroying muscles when the body lacks nutrients is slower than the ectomorph's process.Taking into account what type of metabolism one person has, helps us develop a diet and training plan suitable for that person. The diet and workout plan have to be perfect so that we could entirely recover our body's strength between sessions and have a gradual muscle grow. The person which has ectomorph type of metabolism has to avoid eating under the limit of their caloric need because this will surely lead to body mass reduction. Also the endomorph people have to make sure they don't eat too many calories as that would be very bad for their training program.

When I am talking about muscle grow I am referring to a muscle grow which is proportional to the person's height. A smaller person has to grow a suitable amount of muscles because overgrowing might affect the body image. Think how a small person would look with 300 pounds of muscles. With your personal trainer you have to analyze and think how much muscular mass it's appropriate to gain for your height. To prevent muscular loss and maintain a high percent of muscular gain you have to follow a diet based mostly on proteins. The necessary quantity of proteins is 1,2 – 3,4 grams per body kilogram. Protein diets will contain food which has the biggest amount of protein like: chicken, turkey, beef, fish and almost every animal protein.

The next nutritional elements are carbohydrates; carbohydrates are the main source of energy our body prefers to use. During workout a large quantity of carbohydrates must be consumed to satisfy the body's needs. Endurance depends on how much glucose exists in our body. For intense workout it is recommended to eat 5-6 grams of carbohydrates per body kilogram. Studies show that glucose is deposited as glycogen in the muscular tissue and represents 99, 5 % of the burned energy.

The quantities which are right to eat must be planned by a nutritionist or by your personal trainer; don't eat something because you think or heard is good for you, maybe it contains something that is forbidden in your diet. Ask your nutritionist before you make a meal plan, that way you will prevent including any unhealthy food or eating the wrong quantities. If you are one of the people who want to see muscle grow fast, you need to have patience because bodybuilding needs strict diet, a good workout program and perseverance. Don't get all depressed if you don't see any muscles in two weeks, you cannot grow muscles in such a short time! You probably will see that you feel better and healthier but don't expect to be big in a really short time.

Don't forget to think about vitamins and minerals too as they are very important to muscle growing; eat iron, zinc and calcium rich food and you will notice that you won't have muscular cramps or headaches. If you have an intense workout and notice that you don't gain any muscles you surely don't eat enough calories. Your breakfast should be composed of 500 milliliters of milk, 3 eggs and some cheese so if you have to eat this much for breakfast think about how much you have to eat for lunch or dinner and of course let's not forget the snacks. Supplements are also important for weight and muscle gaining because your food cannot cover all the amount of calories you have to eat; you will need to take some protein based supplements. Also take some vitamins and minerals. DON'T TAKE STEROIDS! I know that the thought of having great muscles in a very short time is nice but steroids don't work. Steroids will do a lot of mess in your body and after you stop taking them your muscles will go as fast as they came. Steroids may be forbidden in your country so if you buy them you also risk to get arrested. As a final word I want to advise you that if you start bodybuilding a lot of your free time will be compromised so if you aren't prepared to sacrifice that you shouldn't start bodybuilding. Also if you don't have a healthy lifestyle from the beginning it's going to be very hard to make changes. Good luck and grow those muscles!