http://perfecthealthdiet.com/2011/08/carbohydrates-and-the-thyroid/

[A low-carb] diet will lead to an elevation of catabolic stress hormones, while [a high-carb diet] has been shown to increase thyroid hormone triiodothyronine (T3), increase testosterone, and decrease cortisol, the anti-hair, pro-misery stress hormone (here, here, here (PDF), & here).

Meanwhile potentially causing:

• increased atherogenetic particles
• increasing blood pressure
• weight gain
• negative mood impacts
• inflammation
• type-II diabetes if left unchecked
• poor lipid panel results
• increased triglycerides
• potential increases of neurological disorders due to plaque formation
• increased risk of heart disease

Yet at most 400 calories of glucose per day can be manufactured from protein. It’s clear that athletes need to eat a fair amount of carbohydrate to avoid a glucose deficiency.

Not if one is keto-adapted. :P

Now let’s look on the glucose side. If 600-800 glucose calories are utilized by the body daily, and at most 400 of those can be manufactured from protein and at most ~300 can be displaced by ketones, then someone on a zero-carb diet is living right on the margin of glucose deficiency.

This literally says nothing about keto-adaptation and the eventually use of free fatty acids for fuel. Most of our tissue will utilize FFA after keto-adaptation with the majority of ketones being utilized by the brain. Glucose deficiency doesn't exist on this diet using the assumptions present.

If 200 glucose calories per day are consumed, and if 400 protein calories are consumed, and if MCT oil (a ketogenic substrate) is consumed to make it easier to generate ketones to displace glucose, then one might just barely meet the body’s structural glucose and protein needs on a ketogenic diet. This is why we recommend that ketogenic diets include at least 200 calories from starch.

LOL. Eat enough protein and you get it all. Literally 0 carbs are required.