Are Your Hormones The Reason You Can’t Lose Weight?

Hormones are the chemical messengers in our body that remind it how to do basically everything.

When it’s our brain’s time to sleep, melatonin soothes us. When we’re exercising, catecholamines drive up our heart rate to pump more blood. And, when it comes to storing or burning fat, several hormones — like insulin and cortisol — give the commands.

In fact, they can be so important in determining how our body treats extra calories that many are tempted to put all the responsibility on them. We’ve all heard some form of “It’s not my fault — my hormones won’t let me lose weight.”

But is this true? We know that energy balance (calories eaten vs. calories burned) governs how much weight we gain or lose… Could hormones throw a big enough wrench in that machine to slow it down? Or worse, stop it completely? Let’s find out.

The Insulin Fairy

No hormone gets blamed for bodyweight woes more than insulin. Highly important, and even more highly misunderstood, insulin is a hormone that performs a lot of different functions in all parts of the body — from the brain to muscle tissue.

Insulin is an anabolic hormone, which means that it helps build other structures in the body. Its most famous function is regulating blood sugar levels. To keep this aggressively simple: when you eat too much food, insulin sends the signal to store the extra glucose as glycogen. However, if your muscles and liver can’t carry anymore glycogen, insulin will store those sugars as fat. This process is a big reason why people associate the word “sugar” with “makes me chubby” and accuse insulin of causing obesity.

And that’s not entirely wrong. If insulin signaling gets disrupted or overtaxed — such as by years of sedentary living while eating too much food — it can lead to big problems for both body composition and health [1]. When you become insulin resistant (as in type 2 diabetes) your body’s ability to regulate energy balance is compromised, and the simplicity of “calories-in vs calories-out” gets complicated.

But, unless you’re diabetic or pre-diabetic, insulin shouldn’t be your boogeyman. For the rest of us, simply exercising (which has a strong, positive effect on insulin resistance [2]) and watching what we eat is more than enough to keep insulin from hurting your goals. As long as you’re not eating in a surplus for many years, eating carbs isn’t going to make you diabetic, and insulin isn’t out to stop you from losing weight.

Thyroid Hormones & Your Metabolic Furnace

Hormones produced by your thyroid (T3 and T4) play an important role in regulating your basal metabolic rate [3]. That’s why it’s common to hear someone complain that their thyroid is to blame for issues with weight gain or control. And while it’s true that some thyroid hormones have a powerful influence on how easy or hard it can be to lose weight [4], this doesn’t tell the whole story.

Hypothyroidism — the disease where your thyroid underproduces the hormones that speed your metabolism — can lead to weight gain, or at least keep you from losing weight. People with this disease might be exercising, eating “right” (tracking macros!) and doing everything to lose weight, but find it nearly impossible. It’s like having all the wood you need for a fire, but no matches to start the flame. The wood piles up.

Could this be why you “can’t lose weight”? Maybe — but probably not. The incidence of hypothyroidism in otherwise healthy people is only 1–2% [5]. Higher chances (maybe around 3.5%) of developing a thyroid problem appear in women more than men, and in the old more than the young. But the odds are still that the “source” of the issue isn’t your thyroid: it’s your habits. (The only way to know for sure is to get screened by a doctor!)

For the 98% of us who can’t blame our body fat on our poor thyroids will have to keep tracking macros and trusting that a calorie deficit will do the trick. Or find another scapegoat… which brings us to cortisol.

Stressing About Cortisol

Cortisol is called a “stress hormone” because it plays a key role in how the body responds to stress. “Stress” can be anything that threatens your body’s desire to keep everything balanced and healthy — whether that’s physical or psychological. Trouble at school, a difficult job, extreme cold, loud noises, intense workouts… your body treats all of these as stress. If daily stressors happen too often or too intensely, we might start releasing too much cortisol.

And that can be a problem. Excess cortisol is related to metabolic disturbances like obesity, metabolic syndrome, insulin sensitivity, and the risk of cardiovascular disease and type 2 diabetes [6,7]. What’s more, elevated cortisol levels have been connected to increased calorie intakes. This probably isn’t too surprising: We tend to eat more when we’re stressed [8]. There isn’t much research on this in humans yet, but it’s pretty clear through animals studies that cortisol can directly increase appetite.

Again, we have to come back to how our lifestyle affects whether these hormones hold us back or not. Exercising and eating less aren’t just the drivers of progress when you want to lose weight — they can also help reduce cortisol over time. The trouble with cortisol is that this takes a long time. One study found that it took 6 months of exercise to decrease daily cortisol [9], and another found that it took about the same time to drop cortisol by eating less [10].

Ironic as it is, the average, healthy person might need to worry a bit more about cortisol than insulin or thyroid hormones. But, in a way, it’s the simplest hormone to understand and control. We all know the “problem areas” of our lives that bring out the most stress. It’s not easy, but limiting the stressful parts of life might help us do more than achieve Zenlike grace: it might let us reach our weight loss goals faster!

The Take Away? Don’t Blame Your Hormones

The science of hormones and how they affect your fat-loss journey can get complicated, fast. This isn’t even close to the whole story: We could talk about growth hormone, about testosterone and estrogen, and many other factors that affect weight loss in one way or another. But that’s not the point.

The point is that these things are rarely the real problem. Even the sinister workings of cortisol, insulin, and thyroid hormones can’t magically add weight to your body. At most, they make it a little harder to shed body fat. And while that might sound bad, it’s also freeing. It means they can’t stop you, they can only slow you down.

So, if you hear someone complaining that they can’t lose weight because of their hormones, reassure them! Tell them the truth: If you’re tracking your macros and exercising regularly, those habits will win in the end.

REFERENCES
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