I've been following this with fascination and have just sent him an email asking - what would happen if he changed the proportion of fats/carbs he consumed.
Assuming carbohydrate intake was set at say 50g (enough to stay out of Keto but low enough to ensure fast fat loss) and then adequate fat was consumed to supply energy but still be in a deficit for the day, how would he feel differently? What sort of deficit could he maintain week to week while still feeling healthy?
For example he is currently consuming a maintenance diet of 400g carbs and 65g fat, if he changed instead to 100g carbs and 200g fat what difference would this make to his health and his mood throughout the day?
If he found he was putting on fat he could simply tweak his ratios, drop down to 50g carbs and 150g fat he could be losing 1.5 lbs a week!
This is obviously completely the opposite of the primal way; getting everything the body requires from an abundance of fresh veg, quality meat, healthy fat sources etc. but as a thought experiment it really excites me!