Fats and Their Effects on the Thyroid/Metabolism

1. Saturated Fat

✅ Supports healthy thyroid function

• Boosts metabolic rate

• Helps stabilize blood sugar

• Shields cells from PUFA-related damage

• Improves T4-to-T3 hormone conversion

Found in:🥥 Coconut oil, 🍫 Butter, 🧀 Cheese, 🥛 Whole milk, 🥩 Beef tallow, 🥚 Egg yolks, 🐮 Cream

2. Monounsaturated Fat (MUFA)

⚠️ Neutral to mildly supportive

• Less harmful than PUFAs

• Can oxidize with heat

• Doesn’t directly support thyroid like saturated fats

Found in:

🥑 Avocados, 🫒 Olive oil, 🐷 Pork fat (lard, ideally pasture-raised)

3. Polyunsaturated Fat (PUFA)

❌ Suppresses thyroid and slows metabolism

• Inhibits T3 at the cellular level

• Blocks the conversion of T4 to T3

• Raises stress hormones like cortisol and adrenaline

• Promotes inflammation and oxidative stress

Found in:🌻 Seed oils (soy, canola, corn, sunflower, safflower), 🥜 Nut butters, 🌰 Seeds, 🥡 Fried/fast food, most processed snacks

Summary:

✅ Best Choices (Supportive)

• Coconut oil (high in MCTs, which can rapidly support ketone production, but missing fat-soluble vitamins)

• Butter

• Dairy fat

• Beef/lamb fat

• Egg yolks

⚠️ Use Occasionally (Neutral to Mildly Supportive)

• Olive oil (real fresh organic cold-pressed olive oil is pretty neutral, but hard to come by)

• Avocado (same with olive oil, often tainted and oxidized)

• Lard - only from pasture-raised pigs (PUFA content varies)

❌ Minimize or Avoid (Thyroid-Suppressive)

• Seed oils – soy, corn, canola, safflower, sunflower

• Nut and seed oils – walnut, flax, almond, sesame

• Highly processed foods – salad dressings, chips, granola bars, fast food

• Deep-fried foods – almost always cooked in unstable PUFA oils