The suggestion that a "zero-carb" or a very low-carb approach (less than 20 grams of total carbs) leads to a higher level of ketones and enhanced fat loss is misleading - this is not how the ketogenic diet works. The main reason why you'll lose weight on a ketogenic diet is simple: you'll naturally eat less because low-carb diets have appetite-suppressing effects . Additionally, following a low-carb approach will help you release and utilise your fat stores more effectively. Although some people see better results with less carbs, most people won't benefit from a "zero-carb" approach.
I personally don't follow a very low-carb diet because I have such a preexisting condition which may have been caused by my calorie-restricting dieting many years ago. My "ideal" level is somewhere at 30 grams of net carbs (light ketosis). By "ideal" I mean a level at which I feel great and maintain a healthy weight. I sometimes eat less carbs out of habit, not because I force myself to follow a very low-carb diet. Following a very low-carb diet (less than 20 grams of total carbs) doesn't help in my case: it made no difference to my appetite or energy levels but I felt worse. You simply need to try it yourself and find your "ideal" carb intake.