I wonder what the PKD people think about it 
I can relate, I need much protein to get satiated myself. Fat doesn’t help if I am hungry and my protein intake is pretty high sometimes.
But I need lots of calories too so I eat more, sometimes way more fat and it’s fine.
My P:E ratio says not much. It can’t say if I ate too much protein (and I don’t use this lightly, I don’t bat an eye if I go over 2g/kg and I surely need way less. but I easily eat way over it with a small P:E ratio and I don’t even have a huge energy need where a small P:E ratio would be advisable!)
There are the people who must be very careful with their protein intake and they prefer it quite low. From my viewpoint, at least. But they need their energy too so their P:E is small and even more so if their energy need is high. But if it’s not true, I can do the same ratios, just with more calories. My protein will be a bit too high for me and they will have their ideally low one.
I don’t know about others but protein percentage doesn’t satiate me. I need enough protein in grams. And calories. And there are more but percentages? They just happen, we can’t predict my satiation from them. I wouldn’t be satiated eating some egg whites or chicken. Okay, I would lose fat like crazy, and muscle muss and my will to live… It’s not needed. We shouldn’t live on protein (and get rabbit starvation syndrome if we do it really well). And we often can afford very much fat compared to protein. We are ketoers here, some of us can get away with more calories, others badly need eating just enough protein… People who get satiated only with high protein and have a tiny calorie limit, they should have a high P:E ratio, indeed. But many people are different.
I got carried away too much again… But that “fat gain” text for smaller P:E ratios upset me. I still can’t handle such things well enough, it seems.