300 grams is not a lot. I don't see how you would grow with 150 grams without eating carbs. If you eat carbs, it's protein sparing and all of the protein can go to building structures. If you're low carbing, most of that protein will be used for energy. The body doesn't store carbs for long term. It has to store protein and fat for the long term. No protein, no glucose, no immunity, etc. That's why being muscular is better for long term health. You don't live too long emaciated without muscles, look at all those starving skinnies in Africa. In order to store protein, you have to eat it in excess. Why do you think women respond to muscular men? They're suppose to, just like men respond to a woman's chest. It's all instinct. If you're only eating 150 grams, you'll maintain, but won't grow. Fat does not turn into muscle, protein does. There's no nitrogen in fat. You don't have to eat 300 everyday, but you do at some point if you want to increase your protein stores aka muscles. How do you expect to grow without eating protein? That's like 95% of the people in the gym, believing that working out makes your muscles bigger. 365 days a year and still look the same. Those muscles need molecules from somewhere, it just doesn't come from outer space or another dimension. Or the other way around, cardio all year round and still look fat and sloppy. Women always compliment me on how great my skin is, I tell them I eat a lot of meat and fat, and they'll just say it's my genetics. It just blows my mind how people don't think diet makes any difference. We're all here because we understand diet does make a difference.
I know protein slowly converts to sugar, that's why you should let your liver handle the glucose making instead of eating carbs. To say that excess protein turns into fat, I personally went thru it, I did not gain fat, I gained muscles. If you can't gain muscles eating that amount of protein, somewhere along the metabolic process, you're missing some vital nutrient or you are already at a genetic setpoint. Go on any steroid forums, those guys are downing protein levels into the 500g. If protein were a waste to eat, these muscle heads would not put much emphasis in it. This should be common knowledge. You really think ancient samurais and knights trained hard and didn't eat a lot of meat(protein). The nobles understood this so well that they made laws that forbade the common person to eat meat, so they can have it all for themselves or their armies. They understood that not allowing the peasants to eat meat would keep them weak and subservient, and besides it's a lot of work back then to raise animals. Can't go passing around the good stuff to the "common man".
Of course you don't want to eat liver all the time. That's just like eating lean meat all the time. You shouldn't eat anything all the time, but you have to eat it sometimes. That just goes back to making sure your diet is balanced.
