If you’ve ever felt confused about protein intake and how much you actually need, that’s not a personal failing—it’s an honest reaction to nutrition science talking out of both sides of its mouth. Government guidelines say one number. Bodybuilding culture says another, several times higher. Longevity researchers are now raising red flags about the high end of that range altogether. Even credentialed experts disagree with each other, sometimes by a factor of three or more.

So before we get into what the newest data actually shows: you’re not confused because you’re doing something wrong. You’re confused because the goalposts keep moving depending on who’s holding the microphone.