PROTEIN!
Ok..let's talk about protein AGAIN cause this macro is so shrouded in false myths. The absolute best studies we have show a MAXIMUM benefit of protein intake at 0.74 grams per pound of bodyweight. Anything more and you basically GET NO ADDITIONAL BENEFIT. Yes only protein builds muscle but eating more of it than your body needs won't build more muscle. When people consume the standard 1.5-2 grams per pound of bodyweight of protein they leave less room for VERY IMPORTANT fats and carbs. Don't eat enough fats and your body goes CATABOLIC meaning you lose muscle. Eat too little carbs and athletic performance declines. The reason why people "feel" better and "keep more muscle" when boosting their protein intake while low carb dieting is because their body is taking the extra protein and turning it into glycogen via a dirty process which could be done BETTER and CLEANER with some more carbs. In other words you're just burning up those extra grams of protein and you would be better off with some more carbs (for glycogen) or with more fat (for ketones). Protein is important but overdoing it only deprives your body of what it needs from fats and/or carbs. Lastly it has been shown that extremely high levels of protein may contribute to some long term health issues. Try what I am saying...you will never go back to the old way again.
I also must point out that when I test people's metabolic types some come out as a needing more or less proteins to carbohydrate ratios. So some may need more protein than others for their body to utilise the fuel.
"The body can only utilize 30-50 grams of protein at one time." FALSE!! This stupid myth is promoted by supplement companies to make sense of the protein amounts they could stuff in their processed chemical bars. Ever notice the total amount of protein in most bodybuilding bars is always between 35-50?? Thats cause if they put anymore it will taste worse. Its all marketing. The truth is that your body can utilize far more protein at one time. In fact, sometimes I eat most of my protein in one meal (around 120 grams). Think about it...if you could only "absorb" 30-50 grams of protein at one time then you could eat MASSIVE meals and not have to worry about getting fat. Of course there is a limit to how much your body can process at one time but your body has a fail proof method of letting you know the limit...you get sick.