What hormones affect your metabolism?

At its core, the idea behind weight loss is simple: you eat fewer calories than you burn, so your body has to burn through the energy it stores as fat instead.

But weight loss isn’t always this straightforward. Your metabolism, or the rate at which your body digests and “burns” calories and nutrients from your diet, is influenced by a ton of hormones that can make or break your weight loss attempts. If you’re struggling to lose weight no matter what you do, it may be time to check in with your hormone levels. 

Insulin is a key player in how your body metabolizes and stores the nutrients that you eat, and it’s perhaps most well-known for its role in carbohydrate metabolism.

When you eat carbohydrates, your body digests the macronutrient and turns it into glucose in your bloodstream. When your body detects high levels of this “blood sugar,” insulin is released in order to shepherd the sugar into your cells to be used for energy. But if there’s more blood sugar present that can be used for energy, it’s instead stored in your adipose (fat) tissue. And if you are consistently in a state of overfeeding, your cells can become less sensitive to the resulting high levels of insulin, leading to insulin resistance.

In short, insulin is the reason that overeating leads to weight gain, and insulin resistance is the driver of some of our most serious metabolic conditions like obesity and Type 2 diabetes.

There are certain dietary interventions that may be helpful for improving your insulin sensitivity and therefore boosting your overall metabolism. For example, both intermittent fasting and low-carb diets like the Keto diet can have positive effects on insulin resistance when done correctly.

There’s another, more insidious player that could be holding your metabolism back: your stress levels.

Cortisol is commonly referred to as your “stress hormone” because its levels tend to rise during periods of pressure and tension. It’s an inherent part of your evolutionary survival instincts: when you’re faced with a dangerous situation, your body gets into fight or flight mode, and this makes changes to your metabolism on a cellular level. In particular, your brain releases a surge of cortisol which inhibits your insulin production. This leaves sugars in your bloodstream instead of getting into your cells, allowing easy access to energy in case you need to make a quick getaway.

But unfortunately, our modern-day stressors have gone far beyond the prehistoric predator-and-prey scenarios, which has bad implications for our metabolism. Elevated cortisol levels can block your insulin production and eventually lead to weight gain, especially around your middle. So while many of us have now come to view stress as a given in the 21st century, this high level of chronic stress isn’t good for your fitness or your overall health.

Other hormones can influence your metabolism from more of a behavioral perspective. One such example of this is leptin, your “satiety” or appetite-suppressing hormone. It’s produced by your fat cells and signals to your brain when you’ve had enough to eat, so it manages your metabolism by limiting the amount of food that you’re eating.

Unfortunately, this can become a complication under circumstances like when you’re trying to lose weight. Because the amount of leptin that your body makes is dependent on the amount of fat you have stored, you may find that you’re eating more and burning fewer calories after losing a significant amount of fat tissue.

Leptin resistance is also an issue: if you have too much fat tissue, your brain can become less responsive to leptin and limit its appetite-suppressing ability.

On the opposite end of the spectrum of leptin is ghrelin. If leptin is considered your “satiety” hormone, ghrelin can be thought of as your “hunger hormone” since part of its duty is to signal to your brain that it’s time to eat and refuel.

Besides increasing your appetite and driving your food intake, ghrelin also plays a role in manipulating your body stores fat. There’s evidence that ghrelin can increase fat storage and inhibit the effects of insulin in carbohydrate metabolism.

Testerone is the primary sex hormone for biological males, though it is also made and used by women.

Your testosterone levels can have a huge influence on how your body burns fat and builds muscle mass. It can increase muscle protein synthesis, which turns amino acids into muscle proteins and leads to muscle growth. In addition, testosterone is also crucial for helping you break down excess fat tissue.

Altogether, having enough testosterone is a big component in reaching any fitness and/or body composition goals that you may have. Because testosterone levels naturally decrease as you age, it’s becoming a major area of focus for people looking to improve their muscle mass, strength, and fat mass. 

Estrogen, one of the primary sex hormones in females, is also a key metabolism-driving hormone. Specifically, estrogen regulates your metabolism and determines how your body stores fat. When estrogen levels are normal, females tend to store more of their fat around their hips and thighs. But as estrogen levels fall, this can slow your metabolism and more fat accumulation around your midsection.

This is an area of particular interest in perimenopausal and menopausal women struggling with weight gain since estrogen levels naturally decline at this life stage. Polycystic ovarian syndrome (PCOS) is another condition that can cause hormonal imbalances.

If you’re having a hard time managing your weight despite watching what you eat and engaging in regular physical activity, your thyroid hormone levels are among some of the first biomarkers you should check.

Your thyroid is an organ that produces hormones that are essential for regulating your metabolism. Here’s how this works:

Together, T3 and T4 provide energy to the cells in almost every part of your body, including the ones responsible for digestion, metabolism, and temperature control, and dictate the speed at which they work.

So an inability to produce enough T4, referred to as hypothyroidism, can result in weight gain as your metabolism slows down. And on the other hand, excessive amounts of thyroid hormones, aka hyperthyroidism, can lead to unexplained and inappropriate weight loss as your metabolism kicks into overdrive.  

Growth hormone, or somatotropin, is another key player in your metabolic arsenal. It’s an “anabolic” hormone: in other words, it helps the tissues in your body grow as you develop (as you can probably guess from its name).

But beyond that, it also plays a role in determining how your body uses its fuel. Specifically, growth hormone can act directly on your fat stores and break them down for fuel when you need more energy. It’s one of the hormones that is directly impacted by obesity — in other words, scientists have discovered that growth hormone levels tend to decrease when you’re obese. The unfortunate result is a vicious cycle where your body isn’t making enough growth hormone to assist with the breakdown of body fat, which can then go on to cause a subsequent increase in fat accumulation

It can also work against you during a weight loss attempt. If you’re in a caloric deficit, growth hormone can signal to your brain that it’s time to start conserving energy, which means a slower rate of fat burn. It’s one of the reasons that weight loss can sometimes feel like an uphill battle! 

As you can see, weight management on a cellular level can be more complicated and involved than the simple calories in/calories out formula. If you feel like you’re doing everything right but are still struggling with weight loss, it could be a sign that there’s something going on with your hormones.

The only way to get real, tangible answers is to test your hormone levels. Taking an at-home hormone test like Base’s Diet Test can give you a window into whether your metabolism-driving hormones are at the levels they need to be to optimize your weight management.

Ultimately, testing your hormones regularly can give you real answers to your weight loss woes.  without having to resort to blindly guessing and changing up your diet without knowing what’s really happening. 

If you’re struggling with weight loss despite having tried every diet and exercise regimen under the sun, getting your metabolism hormones tested is the next action step to take.