When you hear someone say, “Keto affects your hormones,” it might leave you wondering: Which hormones exactly, and how? It’s a good question. Are they talking about insulin, your energy storage hormone? Or cortisol, your stress hormone? Or perhaps the group of substances known collectively as thyroid hormones? Read on to find out and to learn how keto and your hormones interrelate. 

But first, let’s cover some basics. 

What is Keto?

The ketogenic diet is a low-carb diet where fat intake is the primary source of fuel for the body. In other words, it’s a high-fat diet with extremely restricted carb intake. When the body no longer has much in the way of carbohydrates for fuel, it turns to body fat and fats from the diet for energy. This is why it’s such a popular lifestyle to mitigate a variety of health issues, especially those that would benefit from weight loss.

Ideally, the ketogenic diet focuses on high-quality healthy fats, such as grass-fed meats, fish, healthy oils, and high-fat dairy, as well as moderate amounts of protein and low-carb vegetables. In a ketogenic state, fat loss and weight loss are easily achievable if you eat “to your macros” and your body will burn fat on an ongoing basis.

Keto is used for a variety of reasons, including to address health problems such as obesity, weight gain, epilepsy, type 2 diabetes, and metabolic syndrome.

What Are Hormones?

Hormones are your body’s chemical messengers that deliver messages to your cells. These messengers govern nearly every function in your body, from growth to healing to immunity to appetite. Without hormones, your cells wouldn’t know what to do. 

Every second of your life, glands throughout your body release hormones into circulation. A variety of cues tell these glands to release more or less of a given hormone. An example, using the hormone insulin, will help illustrate.

The pancreas is a gland that produces insulin, your blood-sugar boss hormone. You’ll learn more about insulin (and its link to ketosis) soon, but for now, let’s just cover how it gets released. What tells your pancreas to release insulin? If you guessed rising blood sugar, you’d be correct. A blood-sugar spike can be caused by eating carbs, experiencing stress, or even exercise. When your body detects rising blood sugar, it releases insulin to safely sequester this new blood sugar in your cells. This is a naturally occurring, defensive measure by the body to combat high blood sugar (hyperglycemia), which is a dangerous condition. 

Insulin is just one hormone example, of course. Every hormone in your body—be it insulin, cortisol, testosterone, estrogen, or progesterone—is released in response to different cues. Once released, these hormones go on to direct various cellular activities: Everything from fat-burning to the rate at which you breathe.   

Top 5 Hormones Affected by Keto

Changing your diet from a carb-heavy diet to a ketogenic diet twists a lot of internal dials, including your hormonal dials. Following are the top five hormones affected by the keto diet:  

#1: Insulin

Insulin is the key to ketosis. In addition to regulating blood sugar, insulin tells your cells to either burn or store fat. The more insulin released means more store, less insulin means burn. When you eat carbs, your pancreas releases gobs of insulin, inducing fat storage. When you go keto, your pancreas stops releasing insulin and fat-burning ensues. 

Ketones, which are naturally produced by the body to use as fuel in the absence of carbohydrates, are a byproduct of this fat-burning. Consequently, your level of ketosis is determined by your insulin levels.

Insulin, however, doesn’t always work as it should. Some folks get stuck in fat-storage mode, a condition known as insulin resistance. When someone is insulin resistant, their cells stop listening to insulin. This means blood sugar keeps rising, more insulin gets released, and (eventually) type 2 diabetes develops.

The ketogenic diet can help. Multiple well-designed studies (most notably, one sponsored by Virta Health) have shown that a supervised keto diet can reverse insulin resistance, lower blood sugar, and get patients off their diabetes medications.

#2: Cortisol

Closely linked to blood sugar and insulin is cortisol, the much-maligned stress hormone. Cortisol is released by your adrenal cortex (near your kidneys) and influences nearly every human cell. Rising cortisol levels have a number of adverse effects. It:

  • Increases blood sugar levels (glucose)
  • Breaks down muscle
  • Stimulates fat storage
  • Decreases bone building

Because cortisol spikes blood sugar (and therefore insulin), you want to keep cortisol low to promote ketosis. Keeping cortisol low means managing stress, getting enough sleep, exercising, and optimizing electrolytes like sodium and magnesium. Few people know, for instance, that low sodium is linked to high cortisol.

#3: Aldosterone

Aldosterone is the least recognizable hormone on this list, but not for lack of utility. The main function of aldosterone is to regulate blood pressure. It does this job, in part, by regulating sodium and potassium levels. When aldosterone rises (a consequence of rising insulin), it tells your kidneys to excrete potassium and retain sodium. Then blood pressure rises.

Where does keto come in? Since keto lowers insulin levels, it also lowers aldosterone. Low aldosterone is generally desirable, but comes with a poorly reported side effect: sodium deficiency. (Remember, aldosterone helps you retain sodium.) Sodium deficiency, in turn, can lead to a host “keto flu” symptoms. To prevent these symptoms, low-carb folks may need to increase sodium intake. 

#4: Thyroid hormones

Your thyroid gland does not produce one hormone, but several. Your primary thyroid hormones, called T3 and T4, act on most human cells to increase metabolic rate, regulate body weight, build muscle, strengthen bone, and much more.

Although a ketogenic diet has been shown to lower circulating levels of T3, there’s little evidence to suggest that going low-carb negatively affects thyroid function. In fact, the lower levels of thyroid hormones on keto may represent an improvement. 

“A ketogenic diet,” writes long-time ketosis researcher Dr. Stephen Phinney “seems to result in improved thyroid hormone sensitivity (i.e., it takes less hormone to produce the same effect).”

Going keto may also alleviate certain thyroid disorders. In a 2016 trial published in Drug Design, Development and Therapy, autoimmune thyroiditis patients had significant reductions in anti-thyroid antibodies after 3 weeks of low-carb dieting. 

#5: Testosterone

Testosterone is a hormone that helps you build muscle, strengthen bone, and metabolize fat. Men have about 15 times more testosterone than females, but this chemical messenger is still a significant player in a woman’s body.

One small study suggests that a ketogenic diet (combined with resistance training) raises testosterone levels in young men. This makes mechanistic sense, since the keto diet is high in the testosterone precursor, cholesterol. 

MORE: Learn about how the ketogenic diet affects menopause.

The Final Word

There are a number of hormones (chemical messengers that direct the activity of our cells) that interrelate with the keto lifestyle, including insulin, cortisol, aldosterone, thyroid, and testosterone. These interrelations appear to be positive and have health benefits, especially in relation to insulin and cortisol regulation.

Keto also lowers the hormone aldosterone, which directs your body to retain sodium. Because of this, you may need to consume more salt on a keto diet to keep your electrolytes in balance. A keto diet also causes a drop in thyroid hormones, but this may indicate enhanced, rather than depressed, thyroid function.

Finally, it’s been shown that keto raises the hormone testosterone in young men, enabling better muscle-building function.

The bottom line? The relationship between the ketogenic lifestyle and hormones is harmonious, and improved function and balance are two of the many wellness benefits that come along with eating low-carb.  




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