I don’t get why he can’t just do something like keto instead of carnivore. He uses the carnivore diet as an excuse to over indulge on meats and cheeses, and is under the delusion he’ll actually lose weight on it. He technically can, but he’d have to be counting calories, which would get in the way of how he regularly eats.
At least with keto, he’d be getting in some much needed fiber, but even before Jack went carnivore, he generally wouldn’t eat a vegetable unless it was slathered in sauces or fried. What I would give to see him eat some roasted broccoli with only salt, pepper, and olive oil.
His palette is actually worse than a five year old’s, because a lot of five year olds will eat vegetables in some form if it’s presented to them. Peas and carrots probably being some of the vegetables kids will easily eat.