Actually ketones are the preferred brain fuel, it's just that the brain gradually adjusts to this shift. It is much more efficient than having insulin spikes which contribute to neurotransmitter fluctuations within blood plasma/brain. Ketones also provide 7calories of energy, whereas 'routine' fat consumption amounts to 9cals.
But I'm more concerned about the above part of your post - what are we talking about? For one, if you have ketones in your blood it seems absurdial to me that there is adipocyte accumulation going at the same time. Nonetheless, I'm curious to see what evidence you have for this, and what exactly are mutated fat cells?