I have been eating this way (very low carb, high fat, protein in between) for around 3 years now. I have found that for me I can MAINTAIN quite easily at an ideal weight and eating to satiety, but in order to actually LOSE weight, I have to at least have a very small calorie deficit. And though the change is gradual, it is sustainable and quite immediate (just little by little). The amount of that calorie deficit required in order to drop excess varies a lot from one individual to the next though, I think. I am particularly intolerant to hunger, and so I cannot overly emphasize how small of a deficit I will allow for. The nice thing about that though is that the hunger is far more pleasant in the absence of carbs.
The common misconception about the keto diet is that it contains no fibre, and instead the dieter is left eating mountains of bacon rashers, bulletproof coffees, butter and steak. In reality, a well-formulated keto diet will consist of an array of wholefoods including leafy greens, healthy fats from nuts, seeds and coconut, and a small amount of fruit. When keto is done properly, quality fibre is provided in abundance.