The ketogenic diet (KD), characterized by very low carbohydrate, high-fat, and moderate protein intake, has gained popularity for its potential benefits, including weight loss, hunger control, and improved focus. Initially employed to manage epilepsy symptoms, the KD forces the body to utilize fat as its primary fuel source by restricting carbohydrates. This metabolic shift leads to the production of ketone bodies, which are then used instead of glucose. Given the growing interest in KD and its purported effects, this article aims to provide a comprehensive overview of the diet's impact on testosterone levels, considering various factors and potential mechanisms.
Ketogenic Diet Basics
The traditional protocol to achieve ketosis involves limiting protein intake. The goal is to force the body to start using fat as fuel by starving it of carbohydrates. The ketogenic diet is essentially a very low-carb, high-fat, and moderate-protein diet. After an initial period where people often feel pretty rough (dubbed the ‘keto flu’), ketosis kicks in and people can start to enjoy the purported benefits. Most of these benefits stem from the fact that the body produces and uses ketone bodies as fuel (instead of glucose).
The Link Between Obesity, Hypogonadism, and Weight Loss
Obesity and hypogonadism exhibit a bidirectional correlation, with a higher prevalence of hypogonadism observed in obese individuals. Conversely, weight loss has been shown to increase testosterone serum levels. Several approaches are available to contrast weight excess, from simple dietary regimens to more complex surgical procedures. Ketogenic diets (KD) fit in this context and their application is growing year after year, aiming to improve the metabolic and weight patterns in obese patients. In overweight individuals, calorie restriction and the associated fat loss can improve testosterone levels, and this is likely secondary to improved health that goes along with fat loss.
Evidence of Increased Testosterone Levels with Ketogenic Diets
A systematic literature search was performed until April 2022 including studies investigating testosterone levels before and after KD. Seven studies (including eight trials) were included in the analysis for a total of 230 patients, five using normocaloric KD and three very low calories KD (VLCKD). Only three studies enrolled overweight/obese men. A significant total testosterone increase was recorded after any kind of KD considering 111 patients. This increase was more evident considering VLCKD compared to normocaloric KD. Comprehensively, KD improved testosterone levels depending on both patients' age and KD-induced weight loss.
One study focusing on the very low-calorie ketogenic diet (VLCKD) demonstrated its potential for clinically relevant weight loss in obese patients. Twenty-two obese male patients were treated for 28 days with VLCKD. After 7 and 28 days on a VLCKD, a significant and persistent reduction in body weight, BMI, fat mass, blood glucose, insulin and homeostasis model assessment index was observed compared with baseline. TT significantly increased after 7 days and 28 days on a VLCKD. In addition to TT, a significant increase in serum sex hormone-binding globulin levels was observed after 7 and 28 days. However, both calculated free testosterone and LH did not change after 7 or 28 days of VLCKD. Following cessation of VLCKD, hypogonadal subjects achieved a higher percentage of total weight loss, a greater reduction in weight, fat mass and waist circumference and a greater improvement in glycaemia as compared with eugonadal subjects.
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Potential Mechanisms Behind the Testosterone Boost
Several theories attempt to explain how a ketogenic diet can influence testosterone levels. These include increased cholesterol intake and secondary to fat loss via improved health.
Cholesterol Intake and Androgen Synthesis
In general, it is expected to consume between 500-100 mg/d of cholesterol through the ketogenic diet, and may vary beyond this range. Cholesterol serves as a precursor for androgen synthesis. Probably after gastrointestinal tract way this cholesterol amount provides more substrate for androgen formation, thus reflecting on a serum increase of total testosterone. The ketogenic diet and testosterone increase: Is the increased cholesterol intake responsible?
The Role of Fiber
There is also a theory that dietary fibre can impact cholesterol levels and oftentimes fat and fibre within diets are inversely proportional - as one goes up, the other drops. Studies in vegans, who tend to have higher fibre intakes, show that this doesn’t appear to cause issues with testosterone.
Impact on PCOS
PCOS is the most common hormone disorder in women, affecting 7-10% of women of childbearing age. The keto diet is a high fat, low carbohydrate diet that has shown promising effects in women with PCOS. We found an association between the ketogenic diet and an improvement in reproductive hormone levels, which influence fertility, in women with PCOS. They found women with PCOS who were on the keto diet for at least 45 days saw significant weight loss and an improvement in their reproductive hormone levels. Their follicle-stimulating hormone ratio was lower, which means they may have a better chance of ovulating.
Considerations and Caveats
While some studies suggest a positive correlation between KD and testosterone levels, it's crucial to consider potential confounding factors and limitations.
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Calorie Restriction and Body Fat Levels
For one, we know pretty conclusively that under severe calorie restrictions, hormone production starts to become suppressed. Essentially, the body goes into starvation mode and non-vital functions start to get shut down in favour of sheer survival. Along with severely low levels of body fat causing the body to effectively shut down, very low-fat intakes for extended periods can suppress hormone production as steroid hormones such as testosterone are based on the cholesterol molecule .
Glucose and Testosterone Production
Some evidence shows that glucose is required for testosterone production and increased carbs can increase testosterone when calories and fat content are controlled. Some of the evidence for higher carb intakes and testosterone levels comes from studies where training intensity was very high.
Atherosclerosis
The literature regarding the atherogenic effects induced by the KD. thus far has analyzed atheroma plaques in the context of a KD. levels of LDL for its atherogenic potential, i.e. type. cardiovascular protection even with high cholesterol intake.
Potential Risks and Recommendations
Would I recommend going keto just to boost testosterone? Keto has several potential benefits including hunger suppression, increased focus, and more stable energy levels. Some people love it, but it is a very restrictive diet and adherence can be an issue. Overall, to boost your testosterone levels, I recommend eating plenty of vegetables and limiting saturated fat (whether you are keto or not!).
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