Many males (and even females) follow the keto diet for increasing testosterone, which seems like a logical strategy since low-fat diets have been shown to decrease androgen production.

It seems intuitive that eating a high-fat diet, like keto, would do the opposite.

But is that really what happens?

Does the keto diet affect testosterone levels?

Read on as this article takes a deeper look at the research behind testosterone levels and keto, as well as other lifestyle variables that impact androgen production.

What Is Testosterone?

Testosterone is an anabolic androgenic steroid made by the gonads (testes) in humans; since testosterone is an androgen, it promotes the development of male sex features and controls male reproductive functions.

Contrast this with estrogen, which promotes female sex characteristics, such as the development of breast tissue. 

Steroids?

Many people hear the word “steroid” and immediately assume it means something bad, largely because steroids are often used for performance-enhancing purposes.

But steroids are also hormones that our bodies produce naturally (and they are essential for our survival). 

There are five groups of steroids that the human body naturally produces (in both males and females):

  • androgens 
  • estrogens
  • progestins
  • mineralocorticoids
  • glucocorticoids

Testosterone falls under the androgen group. Since testosterone is an androgen, it tends to be much higher in males than it is in females.

However, females still have some testosterone, just like males have some estrogen. 

In fact…

If a man has too much estrogen, he can start to develop breast tissue (gynecomastia). Similarly, when a female has too much testosterone, they may start to grow excessive body hair (even a beard) and experience deepening of their voice.

It’s important to note that such abnormalities are quite uncommon and generally only happen in people who take synthetic forms of androgenic or estrogenic hormones, which throws off the body’s natural balance and production of these steroids.

In other words,

Females don’t need to worry about the keto diet increasing testosterone levels to a significant degree.

There is no conclusive research or anecdotal evidence to suggest that happens. Again, females actually need testosterone and produce it naturally, just like males.

For females that have naturally low testosterone levels, eating a higher-fat diet instead of low-fat, high-carb diet may actually be beneficial (same goes for males).

What Research Has to Say

All steroids in the body are derivatives of cholesterol (yes, the same cholesterol you find in food). The pathway that produces steroids in the body is known as steroidogenesis (image below):

This is ostensibly why eating a low-fat diet decreases testosterone and eating the keto diet for increasing testosterone seems intuitive.

But is that actually the case? The research at this point suggests that the keto diet does, in fact, alter hormonal responses, but not in the way you might think.

Study 1: Low-Fat Diet Reduces Testosterone Levels

This is an older study from the Journal of Steroid Biochemistry.

The study consisted of 30 healthy, middle-aged males that were put on a low-fat, high-fiber/high-carb diet.

The subjects were instructed to eat a diet that was about 25% fat, 57% carbohydrate, and 18% protein (as percentages of average daily calorie intake) for six weeks, after which they switched back to a diet that was higher in fat (about 37% of calorie intake) for 2 weeks.

Findings of the Study

The study found that after six weeks of the experimental low-fat diet, both total and bioactive testosterone values decreased significantly (by about 15% and 12%, respectively). However, after the subjects switched back to a higher-fat diet (about 40% of total daily calorie intake) for two weeks, their testosterone levels went back to the original pre-study/baseline values.

These findings suggest that a low-fat/high-carb diet may negatively impact both total and bioactive testosterone levels in otherwise healthy adult males.

Interestingly, it only took two weeks of a higher-fat diet for the testosterone levels to return to their normal values, indicating that dietary fat does indeed play a key role in testosterone production.

Study 2: Hormonal Responses to Low-Fat Versus High-Fat Diet

This study had a crossover design, meaning the participants spent 10 weeks on one of the experimental diets (either a high-fat/low-fiber diet or low-fat/high-fiber diet) then switched over to the diet.

This study included 43 healthy adult males (ages 19-56), and the diets consisted of either 18.8% or 41% of energy intake from fat (calorie intake on both diet treatments was equal).

Findings of the Study

Average total testosterone levels increased by 13% after 10 weeks on the high-fat diet. Levels of other androgens like DHEAS and dihydrotestosterone also increased by small amounts.

Study 3: Changes in Serum Sex Hormones in Response to Diet

This study was carried out by the same team of researchers as those in Study 1. The experiment consisted of healthy adult males (30 total).

This study was quite similar to Study 1, starting with two weeks of a higher-fat diet (40% of average daily calorie intake) then switching to a six-week low-fat diet (25% average daily calorie intake);

After the six-week test period, the subjects went back to the higher-fat diet for six weeks.

Findings of the Study

Results of this study are nearly identical to those in Study 1; total and bioactive testosterone levels decreased by 15% and 11%, respectively, after six weeks of a low-fat/high-carb diet. After returning to a diet that was higher in fat for six weeks, the total and bioactive testosterone values returned to baseline.

Does Data Suggest That The Keto Dit Affects Testosterone?

In short: Yes.

It is patently clear that nutrients (especially dietary fat) can alter androgen levels in the body. The change in testosterone when switching from a low-fat/high-carb diet to a high-fat diet seems to be modest.

Drawbacks of these studies are that they didn’t reduce carb intake to a significant degree and they generally had low protein intake.

As such, the dietary interventions in these studies are not the same as the keto diet; the main thing the results demonstrate is that there is a positive correlation between fat intake and testosterone/androgen levels in otherwise healthy adults.

Is It Beneficial?

For enhancing athletic performance and improving body composition, a large body of research focuses on androgenic and/or anabolic steroids as they are the most potent hormones for increasing muscle growth and reducing body fat. 

Be careful to note that “androgenic” and “anabolic” are not synonymous terms.

Androgenic steroids are hormones that promote masculine characteristics (such as deepening of the voice and facial hair growth); anabolic steroids are simply hormones that produce growth of certain tissues (such as skeletal muscle) in the body.

Certain steroids, such as testosterone and androstenedione, have both anabolic and androgenic properties. 

Androgens, especially testosterone and androstenedione, play multiple roles in skeletal muscle such as influencing muscle size, strength and muscle energy metabolism.[1]  

It is general knowledge that blood values of testosterone are much higher in males than in females. However, muscle adaptation occurs in both sexes, which can promote testosterone production.

In females, the production of testosterone is mainly dependent upon the conversion of dehydroepiandrosterone (DHEA) and its metabolite DHEA sulfate (DHEAS), which are secreted from the adrenal cortex.

As such, steroidogenesis plays an important role in maintaining muscular regulation and adaptation in both males and females.

In the case of athletes and bodybuilders

The simplest solution for enhancing performance is to inject anabolic steroids, but that is also highly dangerous and can have life-long consequences.

Not to mention that testosterone and other steroids are controlled substances in many countries, carrying felony charges for possession/distribution. 

In the case of the keto diet for increasing testosterone levels…

The evidence suggests the changes are modest and healthy (and certainly more favorable than a low-fat, high-carb diet).

Benefits of Healthy Testosterone Levels

Testosterone has many functions in males and females, ranging from regulating the reproductive system, libido, muscle mass, immune function, and bone density.

Hence, following a keto diet for increasing testosterone levels can have a variety of benefits, including:

  • Increase in libido/sex drive
  • Support lean body mass and muscle tissue
  • Enhance fat loss
  • Boost energy and vitality

Testosterone levels naturally decrease with age in both males and females, so supporting natural testosterone production is imperative as we become older.

There are many reasons scientists research testosterone (and other androgens) are so thoroughly, as it’s quite clear that these hormones have a myriad of beneficial actions in the human body.

For example, research has demonstrated that supplementing with DHEA significantly increases the activity of glycolytic enzymes in skeletal muscle, thereby improving carbohydrate utilization and metabolism.

DHEA may also be converted to derivatives such as 7-keto DHEA which has positive effects on fat burning and metabolism in humans.

Lifestyle Factors that Impact Testosterone Levels

Many things aside from diet can impact testosterone levels. Just because you follow the keto diet for increasing testosterone levels, you won’t experience much change if you’re not also making the necessary lifestyle changes to support healthy endocrine function.

Lifestyle Factors that may increase testosterone

  • Healthy sleep-wake cycles
  • Having a healthy body composition (i.e. normal body fat levels)
  • Routine weight training (at moderate or high intensity)

Lifestyle Factors that may decrease testosterone

  • Being excessively overweight (obesity)
  • Sleep deprivation
  • Anorexia/malnourishment
  • Depression
  • Diabetes (especially type-2 diabetes)
  • Sedentary lifestyle (lack of exercise)
  • Chronic prolonged cardiovascular exercise (e.g. marathon runners, cyclists, etc.)
  • Drinking too much alcohol
  • Xenobiotics (substances that are foreign to the body)

Aside from lifestyle factors, there are various natural supplements that may potentially increase testosterone levels on keto, including ZMA, Eurycoma longifolia (Malaysian ginseng), shilajit, forskolin, and others. However, you shouldn’t rely on these over lifestyle factors if you’re trying to boost testosterone. 

The underlying question is:

Should I follow the keto diet to boost testosterone?

Ultimately, you should not expect the keto diet to drastically increase your testosterone levels.

If you currently have low testosterone levels, there may be a multitude of causes, some of which may stem from endocrine abnormalities that are preventing your body from producing enough testosterone.

You should always consult with your doctor if you suspect you have clinically low testosterone levels. While the keto diet may boost testosterone to a modest degree, it is certainly not a treatment for low testosterone.

Nevertheless, if you have low testosterone, it behooves you to eat more fat and limit your carb intake.

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Elliot received his BS in Biochemistry from the University of Minnesota and has been a freelance writer specializing in nutritional and health sciences for the past 5 years. He is thoroughly passionate about exercise, nutrition, and dietary supplementation, especially how they play a role in human health, longevity, and performance. In his free time you can most likely find him lifting weights at the gym or out hiking through the mountains of Colorado. He will also host the upcoming BioKeto podcast. You can connect with him on Facebook (https://www.facebook.com/elliot.reimers) and Instagram (@eazy_ell)

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