I think it’s highly dependent on the individual. Age, extent and type of metabolic damage, male/female, amount and type of exercise you’re doing, etc., all affect this.
In my 5 years of low carb, I’ve tried so many things I would have a hard time listing them all. I read a book by Jimmy Moore that advocated eating high fat and stating that if you’re still hungry, you haven’t eaten enough fat. So, at one time, I was eating tons of fat bombs, bullet-proof coffee, adding fat to my steak, etc. I could never tell I was full. (Note that this is nowhere near what happens to me on high carb, where I never, ever get satiated.)
I got on twitter and started seeing posts by Ted Naiman. Convinced he was wrong, and protein = blood sugar, I bought a continuous glucose monitor and set out to prove he was wrong. What I found out was the opposite. For me, protein caused me to be full and I had no blood sugar rise I could discern.
So, now I eat a lot of low fat, high protein foods (shrimp, ham, mussels, other lean meats). This does not mean I do not eat fat, as I do, and I still eat some keto meals, as these tend to be easy to make for a family. And fat tastes good, at least animal fat does, so I’ll eat all the fat on meat. I just choose leaner meats overall and choose quite lean meats a lot of times.
I think you can overdo protein, without enough fat. One time, I ate about 1 3/4 pounds of “london broil” in a sitting (after 36+ hours of fasting and a workout), and that’s a very lean meant. It’s somewhere near 200 grams of protein, depending on where you look for the info. I was not hungry – at all – but I felt somewhat sick. I think this is the “rabbit starvation” scenario, where you eat lots of protein with low fat. So, if I buy london broil (always on sale for some reason), I add some type of fat (tallow, pemmican, homemade Italian dressing, etc.) to it.
I think it behooves everyone to test higher or lower protein on yourself. Jimmy Moore and Dr. Limansky tried Ted Naiman’s protein-sparing modified fast (higher protein, but lower calories) and HATED it. (See The Keto Hacking MD podcast.) Jimmy got hypoglycemia. They interviewed quite a few other people, including body builders, and got a wide range of responses for the same parameters (but different foods – again, another confounder is the different foods everyone is eating).
Try eating different levels of protein on yourself.
But I think overall the idea that we need to eat tons of fat is suspect. I’d rather see an emphasis on eating whole foods.