Simply Healthy E33 – The Thyroid

Disclaimer: We’re not endocrinologists!

You are more than a lab value.

Lab values are based off tests run in the 1960s based on high carb standard American diet


What is the Thyroid?

TSH secreted by Pituitary Gland (in your brain)

TSH stimulates the thyroid gland (in your neck)

A gland that secretes hormones

Two main hormones T4, T3

Thyroid function is measured by measuring TSH, T4, T3

Influences fertility, energy, metabolism, body temperature regulation, blood lipids, It

controls the metabolic rate of every organ in the body

You die without a thyroid

Disorders of Thyroid

Hypothyroidism (more common)

People often take levothyroxine

Hyperthyroidism (too much thyroid hormone)

Does diet influence thyroid?

Absolutely, but why?

E.G if you are in famine, you wouldn’t want to have  baby, you would want to slow

your metabolism etc.

Any change in environmental stimuli / lifestyle may affect thyroid

Diet is no exception

T3 increases as carbs increase

(To help metabolise carbohydrates)

When you decrease carbs, T3 decreases

If your on meds, you will need a change

Like Coumadin. Its neither bad nor good just a change

Is this bad? Maybe maybe not

Anecdotally, people do report change in thyroid function when going from SAD to KETO, the question is why?

  1. Calorie restriction lowers thyroid hormone. People often decrease calories because they are full. You may lower your T3
  2. You also need less T3 when keto. More carbs and you need more T3 to metabolism those carbs.
  3. Weight loss itself reduces conversion of T4 to T3 (the active form)
  4. Exercise influences thyroid (too intensively)
  5. Psychological stress influences thyroid
  6. Studies do show decrease in conversion of T4 to T3 with fasting and keto
  7. Eat more you get more conversion

All these things may lower metabolism to conserve energy.


If you feel great, who cares what your thyroid panel comes back at

If you don’t feel right and your thyroid panel is abnormal and you have a history of thyroid issues, adjust medication as needed

Work with your physician.

When changing anything in your environment your thyroid medication MAY need to be changed so you might needs labs checked every 2 week

What does the research show?

Most studies are on rats

Most studies that look at low carb, high fat use PUFAs (corn oil, safflower)

Let’s remind everyone WHY we don’t eat veggie oils EVER!

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-PUFA diet have brown fat that’s less responsive to thyroid hormone. Remember, brown fat is the type that generates heat to keep us warm.

Let’s remind everyone WHAT brown fat is

Rats on a long-term diet high in soybean oil have terrible body temperature regulation, which thyroid function in large part controls.

Let’s remind everyone WHY we don’t eat soybean oil

The more rapeseed meal (from which PUFA-rich canola oil is derived) you feed turkeys,

This reduced thyroid signaling isn’t a function of all polyunsaturated fats, however.

Omega-3 PUFAs, found in seafood, increase thyroid signaling in the liver.

What about a study on Humans?

Jeff Volek ran a low-carb, high-fat study in adults using a diet with Primal-ish fatty acid ratios (8% carbs, 61% fat, 30% protein, with 25% calories coming from SFA, 25% from MUFA, and 11% from PUFA). He didn’t directly measure T3, but the high-fat group had normal T4 and lost significant body fat, which is very hard to do if you’re hypothyroid.

If you have thyroid issues, recognize keto might not work for you. Maybe try LCHF

Lower carbs without ketosis does not influence thyroid function usually


With LCHF you have many of the same benefits with the unlikely result of influencing thyroid

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