Of course it's both!!! We've been hypothesizing toward this for a couple months now. It's a two step process:
1. Turn from sugar-burner to fat-burner. Now your body can "see" the fat.
2. Cut down the amount of fat and food you eat so that you have a FAT deficit. Only then will your body burn the excess fat that you're carrying around.
Mark has always been a skinny minnie. If you can rip your eyes away from the 8-pack abs, you can see the skinny bone structure in his legs. We just aren't all built that way. Blasting through 2500 calories may work for him. I get by on about half that.
I think that one of the faults(?) of Primal is that it sort of glosses over the calorie question by assuming that our bodies will "tell us" when we're full. As if our bodies know exactly how many calories we need and stops us from eating more after we get exactly that amount of calories? Even from an evolution standpoint this is unlikely. Grok still WANTS to be fat, to guard against days when there is a famine. He could afford to gorge on honey and blueberries because (1) he ran out of honey and blueberries fast (2) there actaully WAS famine, on a seasonal basis.
If you let Grok loose in a modern Safeway, he'd be obese within a year.
Jim Henson, you are still wrong. For months you've been espousing that ONLY CICO matters. It is not ONLY CICO.
5'0" female, 45 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently 111.