I would recommend (as a fellow tall guy who was once about 50 lbs. overweight) that after your next fast, when you start eating again, experiment by only eating zero to low carbohydrate foods. Lots of meat and green vegetables. I think you will fine that the fast will kick start ketosis, and the low carb diet will maintain ketosis at a more pleasant level, but the fatty acids in the meat will provide energy, supplemented by the fatty acids being released from your fat cells.