“Not a diet recommended for general use” can be legitimately said of many defined diets and can DEFINITELY be said of the actual eating habits of most western people.

Keto (i.e. any diet that triggers ketones) is a compelling option for numerous reasons, not just epileptics. It’s definitely not a good default for the wider population. And it is of course environmentally and economically inefficient. But ketogenisis is a reality of our biochemistry and shouldn’t be dismissed in the same way as other diets.

Replace the word fad with popular if that works better for you. There has definitely been a lot of buzz around it lately.

I agree. It’s true of many (all?) diets that its proponents tend to overestimate the applicability of any one diet to all people.

Dietary science is at its infancy. Contrary to what most people would assume, we have mountains of anecdotes, mountains of opinions, and very few hard facts. Navigating diet from a fact-first, science-first perspective is deeply frustrating.

'Protein is more filling' is also a part of our biochemistry but I'd still be ok with carnivore diet being called a fad diet

You can do a keto diet without eating meat.

Keto isn’t a high protein diet.

I know. I'm not debating the merits of it, I'm just saying it wasn't a popular diet for the average Joe until recently.

well maybe the reason it's growing in popularity is the fact that generally accepted medical and regulatory advice has been idiotic, focused on reducing fats and replacing them with sugars and carbs which resulted in obesity and diabetic epidemic?

that fad lasted for 50 years, taking that into account it's probably too early to call keto a fad - i barely meet people who even know about it, let alone practice rigorously for any prolonged amount of time.