My understanding is this.

Tryptophan is a very small percentage of the amino acid/protein content. Ricotta is 0 .12g tryptophan per 100g serving. Three times the next highest source plain nongreek yogurt. Other sources are puny.

The gut makes 90-95% of the total seratonin. This cannot pass the blood brain barrier. The brain apparently must makes its own supply. This requires tryptophan to cross. The problem seems to be it is competeing with other proteins. Two mechanisms I found are eating carbohydrates at the same time or working out to fatigue.

I donot fully understand the biochemistry behind either.

My son and I relied on 5-HTP but it has side effects reguarding growth of a youngster.

We are trialing lc ricotta pancakes with real maple syrup.

As for only consuming BCAA 's, IMHO eating a full spectrum of amino acids via real meat like beef, lamb, fish, etc is far more beneficial.

My son was using whey protein to bulk up. When he stopped bothering with protein shakes, I said nothing. Our goal is a healthy mucsle mass from some weight lifting, running, hard farm work and eating high quality proteins like animal meat.

As for appetite, and obesity I suspect real life is more complicated than a mouse study. Currently my youngest, 15yo, is very lean with a five pack,lol, and noticeably larger bicepts. Without using whey protein. He has youth and sports on his side for now.

His older brother needs the seratonin boost, and if that includes adding body fat, yeah. Cant pinch 1/2 inch on that kid. He needs more mucsle and more body fat.

Maybe worth trying him on a n=1 experiment with more whey. Bought reg yogurt instead of greek for his lunch , ricotta pancakes with maple syrup for breakfast. Will see how this works out.