The following Mark's Daily Apple article was written by Mark Sisson, and is narrated by Tina Lehman.

Is keto bad for the thyroid?

Keto is fantastic, everyone says.

It's a great way to lose weight, improve cognition, and stave off degenerative disease.

It may help your performance in the gym and on the track.

It could even give grandpa some respite from Alzheimer's.

But it's hell on your thyroid, right? Keto detractors and proponents alike will often

warn that remaining in ketosis will tank your thyroid. The thyroid's an important gland,

exerting major influence over essential systems like fertility, energy, metabolism, body temperature

regulation, blood lipids, and general wellness.

It controls the metabolic rate of every organ in the body. We want it working well,

so this is a major blow to keto, if the criticism holds true. Fortunately, there's more to this

story. Let's explore.

Up till now, the vast majority of studies on the effects of low-carb high-fat diets on thyroid health have used high-poofa high-fat diets.

Could this confound the results?

Yes.

It turns out that linoleic acid suppresses thyroid signaling.

Rats on a corn oil diet convert less T4 to active T3 than rats on a lard diet.

Rats on a safflower oil diet have a more greatly reduced metabolic response to T3 than

rats on a beef fat diet.

Rats on a high poofa diet have brown fat that's less responsive to thyroid hormone.

Remember, brown fat is the type that generates heat to keep us warm.

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