I did carnivore for ~ 1 year. I was strict on it but allowed dairy/spices/sauces/alcohol. I loved it. I felt great. I've never had an easier time managing my weight (which has yoyo'd for my entire life). I had tons of exercise capacity (I suspect stable blood sugar and creatine from all the meat were most of that). It helped me suspect dairy is relatively insulinegenic for me (which is probably why I'm prone to overeating it like other people eat carbs).

While I think there are benefits to going strict carnivore, most people can probably get 80% of the benefit by reprioritizing protein and replacing carbs with more fat. afaict most people are protein malnourished given modern food guidelines and most fast/convenient/packaged foods are mostly flavored carbs.

As people age, they tend to eat less protein which only exacerbates the decline of endogenous anabolic steroids and our cells sensitivity to them, and eating more protein can help with the decline by encouraging more muscle protein synthesis.