Brown fat burn fat and produces heat. Really? How much? Well in the research it is about 3 calories per hour per pound of fat.
Jack is a neurosurgeon, typically over confident, like the typical surgeon. He has a tendency to overstate a bit (100 pound fish on seven pound line). They need to believe that they know it all to overcome the natural human reluctance of cutting into someone. This is all ego built up in the mind. The reflection of there training, the reflection of the overgrown collective egos that are the medical community. We often work with collective superegos, - municipal governments planning and development departments, to differentiate big egos from super egos.
Even on Paleo, I get bloody hungry. He does not touch on that issue. No help there. The other issue I have not resolved is a tendency to get hungry when stressed, anxiety is high, or boredom strikes (trapped with people). Oh well, shit happens.