Physiologically, the synthesis of new contractile tissue takes time (months and years) , especially in the case of subjects who do not use anabolic drugs. Cases of rapid gains of tens of pounds exist, although they are rare. Examples are starting conditions characterized by severe malnutrition or subjects who had already acquired in the past a given amount of muscle mass then lost following a long stop.
In the first weeks/months the beginner does not immediately benefit from substantial increases in muscle mass but more likely from rapid increases in strength and nervous adaptations, functional to better management of the body and greater efficiency in the recruitment of their muscle fibers.
After this phase, if you train and feed correctly the first 4-5 years will be the most profitable in terms of the amount of muscle mass gained. After these, it is possible to continue to synthesize new muscle tissue but increasingly slowly as the window of adaptation determined by the genetic potential is reduced.
However, if, for example, as often happens, you don’t do things correctly right away, it could take up to 10 years and still be beginners. From this point of view, the more trainable you are, the greater the potential degree of improvement not yet expressed.
Although it is difficult and risky to give muscle growth times as they are strictly subjective and mainly dependent on age, sex and genetics (amount of white fibers and myonuclei, ability to express strength), several authors have estimated approximate average gains of about 10 kg. in the first year up to a progressive reduction of the growth rate to 1 kg of muscle mass in the fourth year – but still values remain to be taken with a grain of salt.
We have already mentioned the importance of the food aspect in allowing and facilitating the synthesis of new muscle tissue. The diet must be functional to your goals ( mass and definition phases ) and this means providing the body with adequate amounts of macronutrients (proteins, carbohydrates and fats), micronutrients and water also to better face training in the gym.
To increase muscle mass it is necessary to have a caloric surplus, on average between 300 and 500 kcal per day compared to the maintenance calorie intake. In this phase, the accumulation of fat is also physiologically inevitable: you cannot grow by always remaining defined. To learn more, read the article on the high-calorie diet .
To make the muscles visible after a bulking phase it is necessary to be in a calorie deficit for several months: on average equal to 300 kcal for women and 500 kcal for men compared to the daily maintenance calorie intake. During this phase it is physiologically unlikely to synthesize new contractile tissue, so the goal will primarily be to preserve the muscle mass acquired. To learn more, read the article on diet in the definition.
There are some cases in which it is possible to witness an increase in muscle mass without varying the amount of fat tissue or even while losing weight. This occurs only in the first months of training in the beginner subject, in those who re-train after a long period of stop or in those who, despite having been training for many years, begin to do it in a much better way. The body recomposition process is much more frequent and rapid, however, in those who abuse doping drugs.
The only supplement that has been shown to directly increase muscle mass is creatine through increased water retention within muscle cells. However, this is a little impacting effect in absolute terms.
The use of some supplements can only indirectly improve muscle mass (including creatine), that is, allowing you to resist fatigue more and thus exposing yourself to greater intensity and volumes. But even in this case, it is absolutely not a key element or strictly necessary, especially if the diet is adequate.