Thyroid and weight: when it’s not about food
Hypothyroidism occurs 5-8 times more often in women than in men and often goes unnoticed for years under the guise of “just tired” and “age.” The thyroid gland sets the pace for the entire metabolism: when it is underactive, the body burns less, feels cold, swells, and holds on to weight despite eating foods that used to keep it in shape. Here, the order matters most: first tests and a doctor, then nutrition. Section — insulin and weight.
Signs Mistaken for Laziness
Fatigue in the morning, even after sleeping. Cold hands and feet. Dry skin, brittle hair, loss of the outer third of the eyebrows. Facial swelling in the mornings. Constipation. Weight increases by 2-5 kg without changes in diet. Slow pulse. Irregular menstrual cycle, heavy periods. Low mood. Three or four signs together — testing is essential.
Thyroid tests
| Marker | Reference range | What the result means | When to test |
|---|---|---|---|
| TSH | 0,4-4,0 mEds/l | above 4 — hypothyroidism is possible; when planning pregnancy, preferably up to 2,5 | in the morning, fasting, outside of acute illness |
| Free T4 | 9-22 pmol/l | below the reference range with high TSH — overt hypothyroidism | together with TSH |
| TPO antibodies | up to 34 IU/ml | above — autoimmune thyroiditis | once for diagnosis |
| Ferritin | 30-100 mcg/l | low levels impair thyroid function | together with TSH |
What the method does for hypothyroidism
The method is not discontinued, but it is modified. The fasting window should be no longer than 14/10; prolonged fasting is excluded: when energy is deficient, the body lowers T3, and TSH creeps upward. Calories should not be below the recommended level. Protein 1,4-1,6 g/kg, iodine from sea fish and seafood twice a week, selenium from eggs, fish, and two Brazil nuts per day. A low-carbohydrate plate is also beneficial: it reduces inflammation and insulin, which is also often high in hypothyroidism. If you have been prescribed levothyroxine, take it on an empty stomach 30-60 minutes before eating; coffee and calcium delay its absorption.
Can and should
- Eating window 12/12-14/10
- Marine fish, seafood 2 times a week
- Protein at every meal
- Strength training 2-3 times a week
- Sleep 7-8 hours
Not allowed or with caution
- Fasting for 24 hours or longer
- Calories below 1400
- Raw cabbage and soy in large quantities with iodine deficiency
- Interval training every day
- Iodine in supplements without testing
When your weight doesn't budge even with treatment
If your TSH is normal while on medication but your weight remains unchanged, look further: fasting insulin, ferritin, sleep, and cortisol. With autoimmune thyroiditis, it often helps to eliminate gluten and dairy for 2-3 months and assess how you feel. And don't expect quick results: metabolism recovers over 3-6 months after hormone levels normalize in hypothyroidism, and weight loss is slower than in a healthy woman — this is expected.
Frequently asked questions
TSH 4.5 — is that already hypothyroidism?
This is subclinical hypothyroidism if T4 is normal. The endocrinologist decides whether treatment is needed, but start adjusting your diet now: a gentler eating window, iodine, selenium, protein.
Can I fast with hypothyroidism?
A short window of 12/12-14/10 — yes, when hormone levels are stable. Longer fasts — no, they lower T3.
Does a low-carbohydrate diet harm the thyroid?
With adequate calorie intake — no. A calorie and energy deficit is harmful, not the absence of bread. Keep your calories within the recommended range and eat enough fat.
- Cycle and Hormones
- Insulin, Thyroid and Weight
- After 40: Perimenopause
- A Woman’s Body and Wellbeing
Reviewed by Anastasia Zhukova, Fitness Trainer • Author of a Nutrition and Training System • Creator of an AI Personal Support Platform
A human has reviewed this material against the method and real client practice.