I think I was a lucky one - as I'm a fat, currently inactive, old lady who was able to get into ketosis fairly quickly by dropping carbs to 20-25g a day and lose.fair bit of weight while eating at that level, Though I think it may have helped that I've always eaten full fat - unfortunately combined with high carbs for some years pre-diagnosis , and I've been able to maintain that weight loss while eating up to about 50g carbs a day since then, and may (or may not) be producing any ketone at any given time,
I believe now that many low carbers who are losing weight and dranatically reducing their glucose levels, not needing to eat all the time oi craving carbs, may very likely be in ketosis/ fat adapted without even trying or knowing. I think their results probably speak for themselves! See
http://www.tuitnutrition.com/2016/01/dont-be-a-ketard1.html for more info.
Robbity