So, if I'm understanding your question correctly, you're asking if it's possible to see muscle gains through a high-protein, semi-fast diet (never come across the term psmf before) despite not exercising? It's certainly the case, depending on a couple factors: -Your previous levels of lean body mass. If you were deficient in muscular tissue due to a low protein diet, your body would attempt to recover to a standard level of lean body mass once it had enough protein to do so; this would be the case whether you were straight-up fasting or just eating really low amounts of protein. This would be especially pronounced if you were more muscular prior to the period of low protein; your body would treat that muscular point as your baseline and attempt to recover to it, regardless of whether you were exercising or not. -Your level of activity: you mentioned that you weren't doing any exercise. Does that mean you literally did nothing but eat and sit on a couch for those 6 weeks? If not, it's possible that the exercise combined with available protein (no matter how light the exercise was; could have just been walking around) jump-started hormonal production that had your body building muscle; again, this would likely be due to you having suboptimal levels of lean body mass and your body's attempt to recover to a healthy level.
Long story short: I'm sure it's possible to put on muscle without exercising, just by changing your diet, but it's not going to work for most people and unless you're extremely fragile due to a previous diet or issue, you might as well start exercising when you make the dietary change. Remember that exercise is going to give you more than just muscle tissue; it'll help to strengthen bones and joints, stimulate hormone production that encourages burning of fat for fuel, and increases neuromuscular strength (which is just as important, if not more so, than the amount of muscle tissue you have).
As you start surfing the web you'll find numerou sites claiming to be the best such as http://www.no2extremerushreview.org/ try to select the one supplement that fits your needs as this issue i.e. gaining muscles without any exercise is only possible if you provide your body the thing that it needs, nutrients and proteins are the main key elements to improve muscle mass and it is only possible with the help of supplements.
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