Im currently doing keto after putting on a bit of weight over a covid lockdown. 5 weeks, 7kg down (83kg -> 76kg). I didnt even start all that heavy, I imagine if someone was really overweight they would lose it even faster. Its pretty easy, you dont even need to eat less, you just dont eat anything that turns into glucose. I guess theres not much difference counting calories vs counting carbs, but it really isnt a big deal to me.
When they don't the studies are usually epidemiological with lots of confounding factors, like the recent PURE-study I saw linked to the other day in thread about keto.
You can find evidence pointing both ways. For instance, it's well studied that in animal models (which can be far better controlled than human populations) high fat diets lead to increased lifespans. The rub here is whether murine models translate to humans, which is not a given.
Keto often has issues because obese people find it as an excuse to continue eating caloric surpluses. It's not magic, and it may not work for everyone. Speaking for myself, doing keto OMAD (one-meal-a-day) is an unbelievable life hack. And my bloodwork backs this up (including a drop in serum LDL after increasing my egg intake dramatically).
Now I am not a nutritionist, but I like looking at studies and seeing what kind of things can be confounding. Or try to spot methodoligal errors.
It’s mostly mental, but you adapt quickly, and there are tons of health benefits beyond weight control.
To a lesser degree: eggs. They are a miracle food imho. Amazing fat/protein/vitamin combo. And anyone talking about cholesterol content hasn’t read any good science on serum cholesterol drivers in the last two decades (you can eat a dozen eggs a day and be fine).