Yesterday I came across this fascinating article. You might know that there was research done on mice showing calorie restriction extends lifespan.
But that's not the end of the story. They took it a step further to see if it wasn't due to something more specific and found out protein restriction had the same effect.
Then took it another step further and found it was restriction of the amino acid methionine that was causing the effect.
So no need to endure hunger and restrict calories more than to maintain a healthy weight!
Also, methionine restriction might not be needed if the intake of glycine is higher, as it helps to clear excess methionine (you need some, it's an essential amino acid).
The main foods that are high in methionine are muscle meats. Glycine is high in bone broths, skins and for example soy protein.
It's not enough to know the content of just one, you need to know both, as it's about the ratio.
It seems like a good idea to decrease methionine intake and increase glycine intake. https://chriskresser.com/do-high-protei ... nd-cancer/https://www.healthaliciousness.com/nutr ... ulator.php