Gaining muscle often also means gaining weight and fat over a period of weeks. But seeing as though people are doing this less and less nowadays, it’s good to know how many kg of muscle it’s possible to take on in a certain amount of time.
The French expert in weight training, David Costa, author of the book Mon Coach Musculation (My Weight Training Coach), explains that there is obviously no one rule for this, since each individual and their bodies are different. But by experimenting with this method of gaining more lean body mass (muscle), he has managed to establish a standard that depends on your level of weight training, so you can know how many kg you can gain in one month.
Beginners (0 to 6 months of experience)
A man who is just starting out with weight training can gain up to 1.5% of their body weight in a month. A woman starting out can gain up to 0.8% of their body weight in a month.
Intermediate (6 months to 2 years)
An intermediate-level man can gain up to 0.8% of their body weight in a month. A woman on this level can gain up to 0.4% of their body weight a month.
Advanced (2 years or more)
A man who is quite advanced in weight training can gain up to 0.4% of their body weight in a month. A woman of the same level can gain up to 0.2% of their body weight in a month.