I think the insulin finding is probably the most significant one that can be drawn from this work and the most interesting, i.e. basal insulin levels increasing has more effect than post meal excursions in adipose fat creation.
As for the lower calorie consumption testing, this study really wasn’t really set up for that, since the participants only ate low carb for a couple of weeks. In most of my experience with low carb it takes at least that long if not longer for the body to adjust to it, and once adjusted it isn’t the miracle of fat being used as a fuel (ketosis) but rather the long term appetite suppression that comes from eating that way that makes people able to lose weight. Too many people think it is a miracle rather than just plain old natural appetite suppression leading to lower calories being consumed.