Why Eat Less & Exercise More Is Terrible Advice For Hypothyroidism


If I had a dollar for every hypothyroid woman out there who has been told to ‘eat less and exercise more’… well, let’s just say I’d be lying on a hammock, on the balcony of my over-the-ocean Maldives summer house retreat, instead of beavering away at my desk on a very brisk winter’s morning.

Sadly, the ‘eat less and exercise more’ message has been bandied around for too many years by General Practitioner (GP’s) Doctors who often have no formal nutrition education, no time to make a reasonable nutritional assessment and even less interest in talking about any treatment for hypothyroidism beyond synthetic, pharmaceutical medication (like levothyroxine).

These GP’s lack any real understanding of the plight of the tired, overweight hypothyroid woman sitting in front of them complaining of fatigue, heavy periods, insomnia, cold intolerance and digestive disturbances.

All they see is a fat, lazy woman who’s blaming her excessive and rapid weight gain on a thyroid problem… so they tell her to eat less and exercise more.

So she does.

And the more she restricts her diet and the more exercise she does, the worse she feels… both because she’s bloody exhausted and also because she’s not dropping any weight, in fact, she’s gained 3 kilograms!!

Eating less and exercising more isn’t working for her. It’s terrible advice. Bloody awful in fact, and here’s why.

Thyroid hormones regulate heat production, energy metabolism and they play a crucial role in nutrient absorption [1].

In fact, there is actual clinical evidence out there, in the medical and scientific world that states that significant changes in body weight is connected to even mild cases of thyroid dysfunction.


Well, best I can tell it’s mainly because of a little hormone called ‘Leptin’… more commonly known as the satiety hormone. Of course, there are other things that impact on weight stabilisation like diet, insulin resistance and genetics, but leptin is a key player.

Leptin is made in fat cells but it acts like a hormone, most importantly keeping the body balanced by suppressing appetite, increasing energy expenditure and surprise surprise it influences Thyroid Stimulating Hormone (TSH) levels.

In more simple terms, leptin is the like a control operator: it tells your brain what to do, your stomach when to eat (and how much) and it also has a chat with some of your fat cells letting them know it’s time to store or burn fat.

So when there’s too much leptin floating around, the signal gets messed up, interrupted or confused (no-one really knows why or how this happens [2], they just know it does).

This means your brain’s not getting the right signals, your stomach doesn’t know whether it’s time to eat or whether you’ve had enough to eat and most importantly, your fat cells don’t know what the hell they are doing so and whether or not it’s time to burn fat.

So what’s this got to do with the ‘eat less and exercise’ more mantra being touted in mainstream medicine?

Well a lot in fact…

When TSH levels rise from a dodgy thyroid, mixed signals get sent to the body telling it that it needs more energy (food) than it actually does creating a ‘positive energy balance’ (this has to do with resting energy expenditure).

If you eat more energy (food) than you need, the body will release leptin which further messes up the signals and encourages fat to be stored… see the problem?

So the body is basically unbalanced due to high leptin levels which encourages excess food intake and then stores that excess as fat.

The flip side of this instability? When you take in less energy (food) than you really need, creating a ‘negative energy balance’ (which may result in temporary weight loss).

At this point, the body effectively thinks there is a food shortage and so it employs certain mechanisms to keep you going until ‘energy balance’ is restored.

That dance between a ‘positive’ and ‘negative’ energy balance is called the ‘yo-yo phenomenon’… and it really is a thing in science-y circles, not just a fad name (true story!).

The problem with the yo-yo phenomenon is that a negative energy balance (a.ka. ‘eat less’) which may lead to short term weight loss cannot be sustained for any extended period (hello anorexia!) and the weight gain that follows it is often more than the original weight loss.

Come on now, who amongst us hasn’t experienced this?

The other problem with the ‘eat less and exercise more’ mantra?

Again, let me revert to science and research… thyroid hormones are affected by physical activity [3].

It’s been said that high intensity exercise like running and cross-fit or prolonged moderate activity like multiple-day-hikes and marathons can create a type of ‘temporary hypothyroidism’ that can take up to 3 days to resolve… in a fit, healthy person with no thyroid disorder.

The reason?

Because high intensity exercise (like running, boxing, cross fit etc) reduces the conversion of Thyroxine (T4) to Triiodothyronine (T3) and increases the amount of reverse T3. But what does that mean?

Well, T4 doesn’t do much except to convert to T3, which is the hormone that gets into the cells and gives them energy. If the T4 either can’t convert to T3 or the T3 can’t get into the cells then it, then it converts to reverse T3.

I’ve heard reverse T3 called the ‘hibernation hormone’ because kind of makes you want to store fat and take a loooonggggg nap, just like hibernating bear.

What Does This All Mean?

Well, if you’re hypothyroid you’re most likely already having thyroid hormone issues like not enough T4, can’t convert T4 to T3 and either way, you’ll feel it by being tired… like all the time.

Throw in an exercise session, like running or cross-fit and you’ve just made it ever harder for your body to do a job it’s already either not doing or not doing very well. And the result? You’ll be ever more tired!

So when the good Doctor says ‘eat less and exercise more’, s/he is effectively telling you to mess around with your energy balance and possibly induce ‘yo-yo phenomenon’ which will over time result in even more weight gain.

And if that isn’t enough… the exercise more part will make you even more tired and exhausted then you were before that terrible advice!

So, What Can You Do?

1) Find out how much energy you really need for you current height and weight.

2) Try to eat that amount of energy every day: no less and no more. To do this, you’ll get the best outcome from nutrient dense foods like quality meat, vegetables, fruits, nuts and seeds.

3) Try low intensity exercise like daily walks, yoga or slow swimming… anything that gets you moving, but won’t leave you exhausted afterwards.

4) Research the benefits of turmeric to support a healthy thyroid gland.

Oh, and you might want to find a new Doctor too! LOL

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Allison Flynn

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