With the recent introduction of very low-carbohydrate diets for weight loss, many have wondered about their effects on the endocrine system.
It is a fact that the keto diet facilitates weight loss.
This diet can be an excellent ally when adequately managed and monitored by a professional.
But does it affect your testosterone levels?
What happens in your testes when you stop eating carbohydrates? Will you synthesize and release the same proportion of sex hormones?
In this article, you will find the answer based on recent scientific studies.
What is a keto diet?
The famous keto diet is a very low-carbohydrate diet. It is short for “ketogenic” diet, which refers to a chemical process called ketosis.
It features an almost complete depletion of carbohydrates in your diet. The carbohydrate count you will consume will be minimal. Thus, your body will start to use fat sources as energy instead of carbohydrates. That is one of the reasons why the keto diet is very good at burning excess fat.
Initially, the keto diet was designed for patients with neurologic conditions. It was effective in treating a type of seizure resistant to other treatments.
In this regard, it was a diet designed initially and recommended by specialists. Later, the keto diet became famous as a weight-loss strategy (1).
How a keto diet works
The ketogenic diet relies on a metabolic pathway known as ketosis. As noted above, it features a minimal amount of daily carbohydrates.
The body commonly uses carbs as an energy source. But in the absence of carbs during the first stages of the keto diet, our metabolism has to use ketosis as an alternative energy source.
When ketosis activates, the body starts to burn fats instead of carbohydrates to get energy. In the process, it’s possible to initially experience symptoms known as keto flu. They would likely stop once we enter ketosis.
Then, ketone bodies take the place of carbohydrates and provide energy to the body. Ketone bodies result from the breakdown of fat and enter the brain and muscle cells very quickly.
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How does a keto diet affect testosterone levels?
In theory, a keto diet should be closely related to testosterone levels. Testosterone production uses cholesterol as the main building block. You need an appropriate fat intake to have normal testosterone levels.
A recent study published by the American Urological Association evaluated popular low-fat diets in over 3,000 men. They found that men adhering to low-fat diets displayed lower blood testosterone than those who didn’t. Restricting fat intake is not a good idea if you’re worried about sex hormones (2).
The ketogenic diet does the opposite. Instead of restricting fats, it turns fatty acids into the primary energy source. The results are promising, and most studies suggest an increase in testosterone levels (3).
Can a keto diet improve testosterone levels?
All of the current studies that evaluated the effects of the keto diet on testosterone show higher levels after adopting this diet. The influence is sometimes considerable, while other studies report a moderate effect.
According to studies, this change can be due to different causes. The most important is an increase in dietary cholesterol.
The classic explanation takes the route of an increase in cholesterol intake. Cholesterol will be readily available for the testis to synthesize testosterone.
Some studies have measured dietary cholesterol intake, and they found that higher cholesterol intake may also increase testosterone levels. However, remember that you only need a limited amount of cholesterol to synthesize this hormone (4).
The ketogenic diet is an excellent aid for those who need to speed up weight loss. It is also suitable for chronic diseases, primarily type 2 diabetes. These patients also tend to exhibit lower testosterone levels, according to studies.
Keep in mind that this type of diet can require monitoring from a professional. Not all of us are suitable candidates, and you may need to run a few tests before starting.
Does a keto diet lower testosterone levels?
So far, no clinical trials suggest a reduction of testosterone levels after adopting a keto diet. The result is usually an increase in testosterone after the keto diet.
Still, it is important to highlight two factors that may lower testosterone levels during keto:
These drugs work by reducing cholesterol levels in the blood. It is the traditional medical treatment for dyslipidemia. But such reduction in cholesterol levels may also impair androgen synthesis.
There is no cholesterol available in the testes, and they stop producing sex hormones. Thus, patients receiving statin therapy during the ketogenic diet might not experience the same increase in testosterone levels.
Using statins in the keto diet is counterproductive if your main goal is to increase testosterone. For instance, total testosterone may fall more than 100 ng/dL after using atorvastatin, as reported in a study (6).
A recent systematic review and meta-analysis provided evidence that calorie restriction reduces testosterone concentration in men. In other words, if your diet is extreme and very low in calories, your testosterone levels may decrease.
Thus, calculating your energy requirements and adjusting your diet accordingly are essential to prevent hormonal imbalances (7).
How the keto diet impacts cholesterol
It is important to highlight that a keto diet increases cholesterol availability. In other words, there is more cholesterol available for androgen production.
Does it increase good or bad cholesterol? The answer depends on the patient and the type of fat you consume.
In some studies, lipid fractions remain untouched (8). Others suggest an increase of bad cholesterol and a decrease of good cholesterol (9). Still, others show the exact opposite effect: an increase of good cholesterol and a reduction of bad cholesterol levels (10).
In this regard, the keto diet could be beneficial for patients with blood lipid problems (9) or harmful (10), depending on how it is designed.
That is why it’s recommended to monitor before, during, and after keto. It’s also recommended to have the diet designed by a professional to ensure optimal results.
What the studies say
One of the most recent studies about the ketogenic diet and testosterone was published in the Journal of strength and conditioning research. The authors used the ketogenic diet for ten weeks compared to the Western diet. They also combined both diets with a resistance training program.
After measuring body composition, blood lipids, testosterone, and other parameters, they reported (8):
- Both groups increased muscle mass and reduced body fat along with body weight. Their strength and power increase were similar.
- There were no changes in serum lipids. Reintroducing carbohydrates very rapidly in the keto diet increased triglyceride levels.
- The Western diet group had a testosterone reduction of 36 ng/dL. The keto diet group increased testosterone levels by 118 ng/dL.
One of the main concerns about the ketogenic diet is atherosclerosis and dyslipidemia. However, as noted in the study above, serum lipids remained unchanged in both groups. It was in the carbohydrate reintroduction phase that triglycerides increased.
According to other studies, some users may even experience decreased serum triglycerides. One of them reported a reduction of 105 mg7dL in obese subjects after using the keto diet for six months (11).
There is no long-term intervention using the keto diet to analyze the effects in atheroma plaques. However, atherosclerosis is a process that takes place when you have an antioxidant imbalance.
Thus, if you consume fatty fish and other sources of healthy fatty acids, a keto diet would confer cardiovascular protection instead of increasing atherosclerosis risk (4).
Weight gain has become a global problem, and low-carb diets are becoming more and more popular. One of them is the keto diet, which uses fat as an energy source instead of carbs. But when you reduce carb intake, what happens with testosterone?
This article has explored the link between keto and testosterone (T). We provided evidence that T levels are not lowered after using keto diets. In fact, it’s quite the opposite, and patients with low T may improve their hormonal balance using keto.
Symptoms of low testosterone include erectile dysfunction, a reduced sex drive, and reduced muscle mass. Keto increases testosterone levels by increasing the availability of cholesterol. With proper testicular function, cholesterol would convert into testosterone and increase our circulating androgen levels.
The keto diet has also been tested for metabolic syndrome and type 2 diabetes. Besides increasing T levels, it also improves insulin resistance, reduces fat mass, and decreases insulin levels. As such, it stands as a promising alternative to restore hormonal balance.
We should highlight that the keto diet should be carefully designed according to accurate caloric and nutrient requirements. You may also need to run a few tests before, during, and after the keto diet to make sure it works for you.
Thus, to stay on the safe side, it’s recommended you talk to a dietitian before using this diet to increase testosterone levels and improve insulin sensitivity.