As with everything, I think it’s complex.
When Diet Doctor came out saying that the actual Diet Doctor had lost weight by using high protein, lower fat, there was a huge kerfuffle on Twitter. It was people for high P:E or against it.
I won’t go into all the details, but Amber O’Hearn brought up the point that some people can’t access their fat in order to be able to eat higher protein. This isn’t a bad theory.
I think part of what happens over time, is that you can access your fat stores. I believe this is primarily “insulin resistance” being lowered, but I don’t know exactly how this works.
But if you HAVE access to your fat, then increasing protein has benefits, including being harder to “burn”.
I think this is why some people get hungry while eating higher protein – they’re effectively starving.
I also think the people who do the best on higher protein tend to be males who have a lot of muscle mass (here’s looking at you, Ted Naiman). This isn’t always true (I’ve seen women who do well on it, too), but in general it seems true.
I think muscle mass helps because it’s an insulin “sink” and I postulate you need higher protein to maintain that mass. Consider a male who weighs 160 pounds. How much protein do they need? Consider the same male, but add 30 pounds of muscle. How much protein do they need?
And I know most people here are anti-insulin (with good reason), but insulin is how muscles grow.
Consider whey protein. Whey protein is so highly insulinogenic that you can use it to lower post-prandial glucose response.
Reconsider the male who weighs 190 pounds with 30 pounds of muscle who has just lifted weights for 60-90 minutes. He eats whey protein, let’s say with some carbs. Where do you think that insulin and blood glucose go? I’d say the muscles get a large portion of it. Maybe all of it.
Now make that male 250 pounds and without some or all of that 30 pounds of muscle (as I was when I stated low carb). Even if this person exercises then eats whey (say, with carbs), where do you think that insulin and blood sugar go? Probably into fat, particularly since insulin resistance of fat will be low.
This is why I think there are so many different opinions about protein. Some people really can’t eat higher protein (they “starve”), yet others can. When I was a body builder, I ate a ton of protein with no issues and did not become obese. (That was caused by beer, pizza, ice cream.)
I also theorize this is why some have a harder time fasting. If you can’t access your fat to get energy, you’re doomed when you fast.
Finally, I think that as your metabolism gets better over time, your resting metabolic rate should go UP. Why? Because you now have access to your fat. I see this anecdotally all the time: people say they exercise more while on low carb, after being on it a while, than they did on high carb.
Makes perfect sense to me, as you have access to energy stored in your fat.
Brad over at Fire in a Bottle has a post related to this:
And Gary Taubes has the theory of the “starving fat man”, where you’re not getting fat because you’re eating more, you’re eating more because you’re getting fat [and energy is locked into that fat].