I'm currently doing a keto diet (mainly to support my girlfriend who wanted to do it, and it's easier if we do it together) and I did lose about 7kg in less than three months so far.

That being said I remain a bit skeptical, for instance it seems to be a lot less effective for her than for me, and I feel like my weight loss may be explained by non "low-carb" factors, mainly that I eat a lot less. I have a sweet tooth and am vegetarian so I normally eat tons of carbs (pasta, rice, bread etc...). I haven't bothered monitory my caloric intake but I'm pretty certain that it dropped significantly. Meanwhile my girlfriend tends to eat relatively "low carb" even outside of this diet, so her food intake changed a lot less.

That's just an anecdote in a sea of contradictory anecdotes, but my general point is that a strict keto diet usually means huge changes in eating habits and I wonder how many of these success stories are simply people eating less/better rather than strictly the low-carb element. Obviously the reality is probably somewhere in the middle...