Whey used to be waste, now it's a supplement cuz protein. Bran is the same, was waste, now gud for ya cuz fiber.

As with any other supplement, if there's an effect, there must be a deficiency to begin with. Therefore, check the overall diet cuz deficient. Consider going low-carb. We start with a crap diet of crap, go low-carb, everything gud for reels. That crap diet of crap mustn't be food. Add whey, feelz gud, diet must be crap. Start with crap diet of crap, add collagen crap, still crap.

So, ya, Teaser, that's no gud logic. Warzooooned!!! (use Torgue's voice for that, it's a Borderlands reference)

Incidentally, dietary protein on its own causes muscle and other tissue growth independently of activity. It could be the insulin through inhibition of proteolysis and stimulation of proteosynthesis, but it could be just the influx of excess protein that enters the on-going protein synthesis, a tipping point of sorts. The idea here is that muscle growth occurs continuously, myostatin inhibits muscle growth, follistatin inhibits myostatin, and then throughout there's protein supply which modulates the potency of those mechanisms especially on the low side but also likely on the high side. Or it could be some signaling by some amino acids or other stuff found in meat for example.