So sometimes going on a fast has the potential to lower a thyroid hormone called T3 and that's

the active form of the thyroid hormone. T4 is the inactive version so I'll explain why

that is. We have the pituitary up here that communicates to the thyroid through this

hormone called thyroid stimulating hormone and one of the main ways that hypothyroidism is

diagnosed is by looking at this hormone right here but when you fast through the ketogenic

diet and do it healthily you're not going to see a change in this hormone right here.

So you are not going to have a true hypothyroid condition or problem. Then the thyroid releases

T4 which is the inactive form of the thyroid hormone. To become activated it has to work

through the liver and to the kidney but it converts from T4 to T3 and T3 is the active

form of the thyroid hormone. But there's something else over here called reverse T3 and the difference

between T3 and reverse T3 is that T3 is active and reverse T3 is an inactive version. Now

I'm not going to get into the tactical part of this but I just simply want to tell you

that what determines the rate and ratio of this conversion to T3 or reverse T3 is the

metabolic need because this has to do with preserving energy. When you do a fast you may

see a slight decrease in T3 and many times it'll still be within the normal range but you're

going to see an increase in the reverse T3. Your body is simply becoming more efficient

with its fuel. So the need for the active thyroid hormone is going to be a little bit less.

The body will then put some of that hormone into a little bit of a reserve until you need

it and it will be released once you are refeeding and you eat again. There are several situations

where you'll see higher amounts of reverse T3. When you're doing fasting or when you're

recovering from a stroke or an injury or overtraining when you're exercising or when you're

recovering from an illness or surgery or when you just have lost a good amount of weight

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