You are exhausted.
You’re gaining weight.
You are constipated.
You’re cold all of the time.
And you are wondering – is it my thyroid?
Followed by the next thought: It MUST be my thyroid. I can take a pill, lose the weight, have so much energy, and live my perfect life.
Isn’t that what thyroid pills do anyway?
Here’s the TRUE answers from an Obesity-Medicine Certified Doctor, Life and Weight Loss coach, and Hashimoto’s thyroid girl herself…
What is Your Thyroid Anyway?
If you are worried about your thyroid and weight gain, you must start by understanding the thyroid gland itself. Let’s make that simple: the thyroid gland secretes thyroid hormone (multiple forms). And, to make it simple, think thyroid = metabolism
When your body does not make enough thyroid hormone, it slows your metabolic rate causing symptoms like:
- Tiredness
- Weight gain
- Constipation
- Swelling on the shins
And, most Moms, can relate to at least a few of those symptoms. That’s why SO many women come to the Doctor’s office wondering about their thyroid.
Is it Likely to Be Your Thyroid?
I’m going to tell you a secret. Your Doctor can see it coming from a mile away. We know what you are hinting at when you start mentioning difficulty losing weight and being tired all of the time. You google searched thyroid disease and are just sure this is the answer to all of your problems. Especially the problem of, “I can’t lose weight – it is my thyroid?”
We also know what will happen next: you are politely going to ask for thyroid testing. It’s ok – you are not alone. It literally happens daily in my office. Equally interesting is the fact that men almost never ask for thyroid testing – of course, they have their testosterone levels to blame.
I’m going to let you in on another secret – it’s probably not your thyroid. The vast majority of patients tested will have NORMAL thyroid levels.
Only 4-10% of patients have subclinical thyroid disease at the highest estimate despite having gained weight.

How Do You Know If It’s Your Thyroid Causing Weight Gain?
Thyroid levels are simple blood tests that can be done at your Doctors office with the above symptoms. There are multiple forms of thyroid hormone made by the gland itself. The initial tests include:
- TSH – thyroid stimulating hormone. A hormone released from the BRAIN that goes to the thyroid to tell the gland to produce hormone. It usually goes the opposite direction of the gland itself (aka: a HIGH level is usually suggestive of low thyroid levels). It is typically the first test ordered when checking thyroid hormone levels.
- Free T3 and Free T4 – non-protein bound forms of the thyroid hormone itself. Multiple forms of the hormone are made and it is possible to have varying results amongst them.
- What about that other testing? The popular “other tests” are second line. More about that in my https://doctormome.com/post/what-about-those-extra-thyroid-tests/ post.
How Does Your Thyroid Cause Weight Gain?
Your thyroid = metabolism, specifically your thyroid = basal metabolic rate. That’s scientific language for how many calories your body requires to run all of its daily functions. If your basal metabolic rate is LOW (as in the case of low thyroid levels), your body needs LESS calories to run its daily functions. It is in lazy mode. So, a person eating the same number of calories can potentially gain weight simply because their metabolic rate is lower than a person with normal thyroid levels.
Do You Lose or Gain Weight When Your Thyroid is Off?
Most people come to the Doctor’s office complaining of weight gain BUT it is possible to have weight loss with thyroid disease as well. As I said above, thyroid= metabolism. So, if your body is making too much thyroid hormone (hyperthyroid, Graves Disease, adenomas) you may have weight loss instead. It is basically the opposite end of the thyroid spectrum. Symptoms that accompany weight loss in high thyroid states include:
- Weight Loss
- Heart racing
- Irregular heart rhythms
- Heat intolerance
- Elevated blood pressure
How Do You Treat Thyroid to Stop Weight Gain?
Your thyroid levels can be checked at your Doctor’s office. If they are found to be low, a thyroid replacement medication will be prescribed. That pill will deliver thyroid hormone to your body and return it to normal levels.
Can You Lose Weight with Thyroid Replacement Medications?
According to studies by the American Thyroid Association, only 50% of patients who are actually found to have low thyroid levels AND start treatment with thyroid replacement medication will lose any weight at all. Of those that did lose weight, the average was 8-9 pounds.
Allow me to illustrate:

Living with Hypothyroid
So, I have low thyroid levels as you can see above. Specifically, I have Hashimoto’s Hypothyroid. And my disease progression had NOTHING to do with my weight.
The truth is that my thyroid just started to burn out with time. My weight had little to do with it. And, despite what many will try to sell you, there is no “thyroid diet”. I promise. I’ll let you know when any diet research supports the greatest thyroid diet. It doesn’t exist.
Here is what I did notice when I promised my Doctor to consistently take my thyroid replacement: no weight loss. I did notice an improvement in energy, though. Of course, that could have been the baby getting closer to sleeping through the night. And my constipation improved – TMI but true.
Can’t You Just Take Thyroid Medicine to Lose Weight?
This one is simple: NO. Causing your thyroid levels to become too high is dangerous for your health, especially your heart. See symptoms of high thyroid levels above. It is not worth it to POTENTIALLY lose a few pounds.
So, should you check your thyroid levels anyway?
The effects of thyroid hormone can be so confusing for patients. If you are having symptoms, they are easy to check. Your Doctor will likely agree to testing as long as you are symptomatic.
I am not opposed to checking those tests by any means – just be reasonable about the outcomes of treatment if indicated. If your thyroid levels are low and you start replacement, you WILL likely notice an improvement in energy, hair loss, constipation, and dry skin and you just might get a LITTLE weight loss with it.
Could It Be Menopause or PCOS Instead Causing Weight Gain?
There are other “hormonal” imbalances that can cause women to gain weight. Think pregnancy, menopause, PCOS. The biggest indicator to tell the difference between these diseases and thyroid disease is simple for most: menstrual periods. Most women do not see a big change in periods with thyroid disease while they do with these other diseases:
- Menopause – defined as a year without a period. Obviously, that year takes awhile and additional symptoms develop during that time frame for most women. Hot flashes and mood swings are the most common additional symptoms.
- PCOS – Polycystic Ovarian Syndrome. Women with. PCOS. have irregular to absent periods. They also have male-pattern hair growth and are at risk for insulin-resistance diabetes. Found in a younger age-range woman than menopause.
Simple Solution:
If you have gained a few pounds, feel more tired all of the time, are constipated, or have noticed hair loss, it may be that your thyroid levels are low. Get the blood test. If you have gained half a person in pounds, cheeseburgers, fries, and a coke are more likely to be the culprit. Weight loss coaching is for you!
For more information on thyroid, check out: https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/thyroid-dysfunction-screening