Hold the bun and sauce ?
Then maybe Keto in the wildš
http://fox8.com/2018/05/05/wisconsin-man-eats-30000th-big-mac-hamburger/amp/
Gorske says heās eaten at least one Big Mac almost every day since May 17, 1972. He has kept most of the boxes or receipts or has made specific notes in calendars that heās kept
He is local to me I have seen several interviews with him, I would be willing to bet he is keto although not intentionally. He only eats big macs, and not the fries. So he is probably getting 35-40g of carbs.
If heās fine (like he says), imagine winning the genetic lottery and then spending it all on Big Macs. Donāt get me wrong, I like a Big Mac now and again (not since Keto but one day, again), but every day for 46 years - and thatās an average of 2 per day so he is not keto (16,800 days) - is a misuse of a god given carb tolerance 
Could be, I should find out what one he goes to and one see if I can talk to him.
IMO, two possible things are at work here. One, as was previously mentioned, heās not eating a lot of other carbs. If so, the six bun portions are not enough to raise glycogen levels to the point of overcompensation, and since we donāt know what else he eats, he may also practice caloric restriction. Either way, glycogen levels are kept at a level that doesnāt cause overcompensation.
Two, he may possess the genetic trait that doesnāt allow leptin resistance to quickly rise. He may be one of those naturally lean people who donāt easily gain fat. If this is so, and he does follow an overall Carb based pattern, Iād expect him to still have some diet related health issues, despite not being overweight.
Fathead style. Donāt eat fries, donāt drink sugar coke, keep it <1ļøā£0ļøā£0ļøā£ grams/day. Get 80% of the benefit without ever skimming ketosis.