- Hormones can make weight gain more likely, but rarely explain all of it.
- Common culprits: PCOS, menopause, insulin resistance, low testosterone, thyroid problems and some medications.
- Most are easy to test for through your family doctor.
- Treating the cause often makes weight loss easier, alongside diet and activity.
If you’re gaining weight despite eating carefully, or you have other symptoms, a hormonal cause is worth checking. This guide covers the most common ones, the tests to ask for and Canadian resources.
Common hormonal causes
| Condition | Clues | Tests |
|---|---|---|
| Polycystic ovary syndrome (PCOS) | Irregular periods, acne, excess hair, weight gain | Hormone panel, ultrasound, glucose |
| Menopause and perimenopause | Hot flashes, sleep changes, weight shifting to the abdomen | Usually diagnosed by symptoms and age |
| Insulin resistance and prediabetes | Abdominal weight, fatigue, family history | Fasting glucose, HbA1c |
| Low testosterone (men) | Low libido, fatigue, loss of muscle | Two morning testosterone tests |
| Hypothyroidism | Fatigue, cold intolerance, dry skin | TSH |
| Cushing’s syndrome (rare) | Rapid central weight gain, purple stretch marks | Specialized cortisol tests |
Medications
Several medications can cause weight gain, including some antidepressants, antipsychotics, diabetes medications, corticosteroids such as prednisone, and some contraceptives. Don’t stop a medication on your own; ask your doctor whether an alternative exists.
What helps
- Treating the condition, for example metformin for insulin resistance, or hormone therapy for menopause symptoms where appropriate
- Strength training, which improves insulin sensitivity
- Protein and fibre for appetite control
- Sleep, which affects appetite hormones
Canadian resources
- Your family doctor for testing and referral to an endocrinologist
- Diabetes Canada for prediabetes and diabetes information
- The Menopause Foundation of Canada and the Society of Obstetricians and Gynaecologists of Canada’s menopause resources
- Obesity Canada for evidence-based weight management information
Men with symptoms of low testosterone can read our TRT in Canada guide; thyroid questions are covered in our thyroid guide.
Frequently asked questions
Can hormones cause weight gain?
Yes. PCOS, menopause, insulin resistance, low testosterone and thyroid problems can all contribute.
What blood tests check for hormonal weight gain?
Common ones include TSH, fasting glucose, HbA1c, and sex hormones depending on symptoms.
Does menopause cause weight gain?
It shifts fat toward the abdomen and coincides with changes in activity and sleep; strength training and protein help.
Where can I get help in Canada?
Start with your family doctor; Diabetes Canada, Obesity Canada and the Menopause Foundation of Canada have reliable information.
This article is general information for adults in Canada, not medical advice. Talk to a doctor or pharmacist before using any prescription drug, anabolic steroid or research compound, and get bloodwork done. If you’re in crisis, call or text 9-8-8 (Suicide Crisis Helpline) any time.
