https://www.reddit.com/r/keto would disagree with you. I myself stay below 20g of carbohydrates per day, and I lose ~3lbs a week on the diet, while eating cheese, meat, and green vegetables. I feel phenomenal, still get to eat food I enjoy, and wouldn't go back to a traditional carbohydrate-heavy diet if I was paid to.
No disagreements on keto being useful for many. For those who want to maintain their weight, though, it's not often the right diet. So I'd argue it's not "general-purpose."
This line gets parroted around here constantly (its just thermodynamics! calories in calories out!), yet more evidence continues to be provided that macronutrient balance matters, as does gut bacteria.
EDIT: What if dieting turns out to be as easy as naturally selecting bacteria for the gut that can't break down carbohydrates easily, and selling it as a probiotic pill that replaces you're existing gut bacteria? Wouldn't that be a huge win for public health policy?
And before anyone comes in and says that's not possible, check out this women who became obese from a fecal transplant from an overweight donor:
http://www.upi.com/Health_News/2015/02/04/Woman-becomes-obes...
Sure, it might be what you need if you start out in an opposite but equally unhealthy state, but in the long run consistent weight loss is fatal.
It might not feel relevant to you, but large parts of the population in the world find themselves in that very situation through no choice of their own.
No. Really, healthy and unhealthy diets aren't binary categories, diets are more are less healthy than others, and there are usually going to be more healthy options than a diet on which you maintain a pre-existing unhealthy excess of body fat.
And, what those diets will have in common, is that you'll lose body fat on them (probably also weight, though that's less certain.)
> Sure, it might be what you need if you start out in an opposite but equally unhealthy state, but in the long run consistent weight loss is fatal.
In the long run, living is fatal, with a 100% mortality rate. But a diet on which you (with your current body weight) are losing weight is not necessarily one on which you will consistently lose weight without limit; one which would maintain a lower but healthy weight will cause you to lose weight while you are above that weight. And would cause you to gain weight if you are below that weight.
Not at all. If you're carrying excessive fat around, you should be modifying your diet in order to shed that excessive fat. If your body composition is healthy, then you should be on a diet that a) is providing both a proper ratio of macronutrients and b) enough calories that you're not losing muscle mass.
Ketosis is a multifaceted, complex, biological process that depends on many variables. However, it is potentially somewhere to start investigating a 'critical limit' to judge how much sugar can be processed by your body.