Thyroid and Weight in Women

The thyroid is a small butterfly-shaped gland at the base of the neck, but it plays an enormous role in regulating metabolism and weight. Thyroid disorders are very common in women, affecting one in eight during their lifetime. In this comprehensive guide, we'll explore the relationship between thyroid and weight, and how nutrition can support thyroid function and help you regulate your weight.

What Is the Thyroid and Its Functions?

The thyroid produces two main hormones:

• T4 (Thyroxine): The primary hormone produced by the gland
• T3 (Triiodothyronine): The active form that T4 converts to in tissues

These hormones regulate:

• Metabolic rate (how many calories you burn at rest)
• Energy production
• Body temperature
• Heart rate
• Digestive functions
• Mood and mental functions
• Hair, nail, and skin growth

In short: The thyroid is your body's thermostat. When it works properly, everything is balanced. When it malfunctions, everything gets disrupted.

Thyroid Disorders

1. Hypothyroidism

Most common. The gland doesn't produce enough hormones.

Symptoms:

• Weight gain or difficulty losing weight
• Severe fatigue and exhaustion
• Constant feeling cold
• Constipation
• Dry, cracked skin
• Hair loss
• Depression and brain fog
• Muscle weakness and aches
• Heavy or irregular menstrual cycles
• Slow heart rate

Most common cause: Hashimoto's thyroiditis - autoimmune disease where body attacks thyroid.

Other causes: Iodine deficiency, certain medications, partial thyroid removal, radioactive iodine treatment.

2. Hyperthyroidism

Less common. Gland produces too much hormone.

Symptoms:

• Unintentional weight loss despite eating a lot
• Rapid heartbeat or palpitations
• Anxiety and nervousness
• Hand tremors
• Excessive sweating and feeling hot
• Diarrhea
• Difficulty sleeping
• Swelling at base of neck (enlarged gland)
• Bulging eyes (in Graves' case)
• Light or absent menstrual periods

Most common cause: Graves' disease - autoimmune disease.

Thyroid and Weight: Why the Relationship Is Complex?

Hypothyroidism and Weight Gain

When thyroid hormones are low:

• Metabolism slows - you burn fewer calories at rest
• Fluids and salt are retained
• You feel severely fatigued - your activity decreases
• Digestion slows - constipation and bloating

But actual gain is usually only 2-5 kg (mostly fluids). If gain is more, there may be other factors (eating more, moving less, insulin resistance).

Hyperthyroidism and Weight Loss

Metabolism speeds up unhealthily. You lose weight but also:

• Lose muscle
• Feel extremely hungry
• Heart works too fast (dangerous)
• Anxiety and exhaustion

After Treatment

When treating hyperthyroidism, metabolism returns to normal, and you may gain weight. When treating hypothyroidism with hormones, losing weight should become easier, but not automatic - you still need healthy diet.

Essential Nutrients for Thyroid

1. Iodine: The Foundation

Iodine is essential for producing thyroid hormones. T3 and T4 are made from tyrosine (amino acid) and iodine.

Daily recommended amount: 150 micrograms (220 for pregnant, 290 for breastfeeding)

Iodine deficiency causes: Hypothyroidism, goiter

Excess iodine may cause: Hyperthyroidism or hypothyroidism (especially in Hashimoto's)

Best sources:

• Iodized table salt (half teaspoon = 150 micrograms)
• Fish and seafood (cod, tuna, shrimp)
• Seaweed (nori, wakame) - but cautiously, some contain very high amounts
• Dairy products (due to cattle feed)
• Eggs

Important: If you have Hashimoto's, consult your doctor about iodine amount. Excess may increase autoimmunity in some people.

2. Selenium: The Converter and Protector

Selenium is essential for:

• Converting T4 to T3 (active form)
• Protecting thyroid from oxidation
• Reducing antibodies in Hashimoto's

Recommended amount: 55 micrograms daily

Best sources:

• Brazil nuts: 1-2 daily sufficient (beware excess)
• Tuna, salmon, sardines
• Eggs
• Chicken, turkey
• Sunflower seeds

Studies showed selenium supplements reduce antibodies in Hashimoto's.

3. Zinc: The Helper

Zinc helps produce thyroid hormones and convert T4 to T3.

Recommended amount: 8-11 mg daily

Sources:

• Lean red meats
• Poultry
• Seafood (oysters, crab)
• Legumes
• Nuts and pumpkin seeds
• Dairy products

4. Iron: For Transporting Hormones

Iron deficiency is linked to hypothyroidism. Iron is important for enzymes producing thyroid hormones.

Recommended amount: 18 mg for pre-menopausal women, 8 mg after

Sources:

• Red meats, liver
• Poultry
• Spinach and leafy greens
• Legumes
• Fortified cereals

Take with vitamin C to increase absorption.

5. Vitamin D: The Regulator

Vitamin D deficiency is very common in autoimmune thyroid diseases.

Recommended amount: 600-800 IU (but may need more if deficient)

Sources:

• Sun exposure 15-20 minutes daily
• Fatty fish
• Egg yolk
• Fortified foods
• Supplements (D3 better than D2)

6. B Vitamins: For Energy and Metabolism

Especially B12 (commonly deficient in Hashimoto's) and B6.

Sources:

• Meats and poultry
• Fish
• Eggs
• Dairy products
• Whole grains
• Leafy vegetables

7. Tyrosine: The Essential Amino Acid

Tyrosine is the basic component of thyroid hormones (with iodine).

Sources:

• Meats and poultry
• Fish
• Eggs
• Dairy products
• Almonds
• Avocado
• Banana

Balanced diet usually provides adequate amount. Supplements unnecessary except by prescription.

Foods That May Hinder Thyroid Function

1. Soy (In Large Amounts)

Soy contains isoflavones that may interfere with thyroid hormone absorption and function.

Reduce: Soy milk, tofu, edamame, isolated soy protein

Small amounts (like soy sauce or miso) usually safe.

2. Raw Cruciferous Vegetables (In Large Amounts)

Contain goitrogens that may interfere with iodine absorption.

Cruciferous vegetables: Broccoli, cauliflower, cabbage, Brussels sprouts, kale

Solution:

• Cook them - cooking deactivates most goitrogens
• Consume in moderation if raw
• If you have adequate iodine, usually no problem

3. Gluten (If You Have Hashimoto's)

Strong link between Hashimoto's and gluten sensitivity/celiac.

Try gluten-free diet for 3 months:

Studies showed reduced antibodies and improved symptoms in some patients.

4. Processed Foods and Sugars

Increase inflammation and disrupt hormonal balance.

5. Excess Alcohol

Suppresses thyroid function and harms T4 to T3 conversion.

Nutrition Plan to Support Thyroid and Weight Loss

Principles

1. Adequate calories: Don't go below 1200 - slows metabolism more
2. Adequate protein: 1-1.2 g/kg weight to support muscles and metabolism
3. Complex carbohydrates: For sustained energy
4. Healthy fats: For hormone production
5. Fiber: For healthy digestion (problem in hypothyroidism)
6. Regular meals: For sugar and metabolism stability

One-Day Plan (1600 calories)

Breakfast (400 calories):

• Two scrambled eggs
• Two slices whole wheat bread
• Half avocado
• Tomatoes

Snack 1 (150 calories):

• Greek yogurt
• Handful berries

Lunch (450 calories):

• Grilled salmon (100g)
• Quinoa (half cup)
• Steamed broccoli and carrots
• Salad with olive oil

Snack 2 (150 calories):

• 2 Brazil nuts
• Apple

Dinner (450 calories):

• Grilled chicken breast (120g)
• Sweet potato
• Cooked spinach
• Salad

Tips for Weight Loss with Hypothyroidism

1. Ensure correct treatment: Weight loss very difficult if hormones unbalanced. Consult your doctor.
2. Be patient: Weight loss slower with hypothyroidism. Aim for 0.25-0.5 kg weekly.
3. Focus on protein: In every meal to support metabolism and muscles.
4. Strength training: To build muscles that burn more calories.
5. Don't overdo cardio: May increase cortisol and slow metabolism more.
6. Sleep adequately: 7-9 hours. Poor sleep increases cortisol and weight loss difficulty.
7. Reduce stress: High cortisol suppresses thyroid function and increases weight.
8. Avoid crash diets: Slow metabolism more and lower T3.
9. Monitor progress other ways: Energy, mood, clothes, measurements - not just weight.

Exercise and Thyroid

With Hypothyroidism

Best:

• Strength training 2-3 times weekly
• Moderate walking 30 minutes daily
• Yoga to reduce stress
• Swimming

Avoid: Excessive intense cardio - may increase cortisol and lower T3 more

With Hyperthyroidism

Rest more during active period. After controlling condition, gradually return to exercise.

When to Test Thyroid?

Test if you have:

• Unexplained weight gain or loss
• Persistent severe fatigue
• Hair loss
• Dry skin or excessive sweating
• Chronic constipation or diarrhea
• Menstrual irregularities
• Depression or anxiety
• Difficulty tolerating cold or heat
• Family history of thyroid diseases

Tests

• TSH (Thyroid Stimulating Hormone): Primary test
• Free T4: To confirm diagnosis
• Free T3: If TSH and T4 normal but symptoms present
• Antibodies (Anti-TPO, Anti-Tg): To diagnose Hashimoto's or Graves'

Note: Normal range for TSH: 0.4-4.0, but optimal for feeling well: 1.0-2.0 for most people.

Frequently Asked Questions

I take thyroid medication, why don't I lose weight?

Medication corrects hormones but doesn't burn fat automatically. You still need calorie deficit (eat less, move more). Also, ensure your dose is optimal - consult your doctor.

Should I avoid gluten?

If you have Hashimoto's, try gluten-free diet for 3 months. About 30% of Hashimoto's patients have gluten sensitivity and symptoms improve.

When do I take thyroid medication?

On empty stomach, 30-60 minutes before breakfast. Don't take with coffee, calcium, iron, or fiber-rich foods - they reduce absorption. Wait at least one hour.

Is intermittent fasting safe with hypothyroidism?

May benefit some women, harm others. If you try it and feel severely fatigued, cold, or symptoms worsen, stop. Consult your doctor.

Are natural thyroid supplements better?

Some people prefer desiccated thyroid (Armour Thyroid), but studies don't prove superiority. Synthetic levothyroxine (T4) is safe and effective. Consult your doctor.

How long after starting treatment until I feel better?

Most people start feeling better within 2-4 weeks. Full improvement may take 2-3 months. Hormones need time to stabilize.

Does hypothyroidism cause insulin resistance?

Yes, untreated hypothyroidism may cause or worsen insulin resistance, increasing weight loss difficulty. Treating thyroid improves insulin sensitivity.

Medical Disclaimer

The information in this article is for educational purposes and does not replace consultation with a specialist doctor. Thyroid disorders require accurate medical diagnosis and regular follow-up. Do not stop or change your medication dose without consulting your doctor. Do not take supplements without medical approval.

Need a Nutrition Plan to Support Your Thyroid?

Dr. Mai Obeid, Clinical Nutritionist, specializes in thyroid disorders and weight loss. Book your consultation for a personalized plan supporting your medical treatment.

Contact via WhatsApp: +961 81 337 132