He probably just needs some carbs.
#LMT
Finally Chris talks some sense, the primary fuel for the brain is glucose, although preferred from non refined plant based sources. Bananas, apples, etc.
(My Bold).
I'm not sure the brain
has a primary fuel - most brain tissue works equally well on ketones or glucose. The remaining tissues that are actually glucose dependent (those cells that lack mitochondria) can easily be supplied by glucose manufactured in the liver.
Some children with intractable epilepsy find their brains work much better on ketones - or at least, malfunction less.
A wholly unethical piece of research was done in the early 70s to prove that brains work fine on ketones. They took several diabetics, adapted them to a ketogenic diet, then pumped them so full of insulin, their blood glucose level was somewhere around 1mmol - a level which should have at the very least rendered them comatose. Not only were they still alive, they seemed completely unaffected, proving that their brains could work just fine without glucose.
Most tissue types can use ketones for fuel. Skeletal muscle prefers to burn free fatty acid over ketones, but requires increasing amounts of glucose in order to work anaerobically; FFAs just don't burn hot enough when you're doing your birthday squats.
