Does Intermittent Fasting Increase Testosterone?

Key takeaways:

• Intermittent fasting (IF) is an eating pattern involving alternating periods of fasting and feeding.
• Available scientific evidence suggests intermittent fasting may lower testosterone levels.
• Potential benefits of intermittent fasting include weight loss, improved insulin sensitivity, and reduced inflammation, whereas some disadvantages include nutrient deficiencies and hormonal imbalances, such as decreased testosterone levels.
• Individual variation exists in response to IF, and consulting a healthcare provider is essential before starting any new diet regimen.

Intermittent fasting (IF) is a dietary approach that alternates between periods of eating and fasting. It has gained significant attention for its potential health benefits, from weight loss to improved metabolic health.  

Popular intermittent fasting methods include the time-restricted feeding (TRF)—16/8 (fast for 16 hours, eat during an 8-hour window) and the 5:2 (eat normally for 5 days, restrict calories for 2 days) protocols. There is also the 12/12 method (fast for 12 hours and eat within a 12-hour window).

Testosterone is the main male hormone. It regulates male sex differentiation, the development of male sex traits, sperm production, libido, and fertility. Additionally, this hormone plays a key role in building muscle by stimulating the production of muscle proteins.

Does fasting increase testosterone?

Study results on the effects of fasting on testosterone are mixed, but several available studies suggest that intermittent fasting does not increase testosterone levels. Instead, the studies indicate that fasting may lower testosterone levels.

A 2016 study demonstrated that testosterone levels were notably lower in individuals following eight weeks of time-restricted feeding (TRF) diet.

Another study by Stratton et al. in 2020 highlighted no increase in testosterone levels in 26 active males after 4 weeks of TRF. There were significant decreases in their testosterone levels.

Moro et al. also reported that testosterone levels decreased in 16 under-23 cyclists who were randomly assigned to a TRF group. Additionally, TRF reduced body weight and fat mass without affecting lean mass. A recent study in 2021 reported that after 12 months of the TRE diet, testosterone was significantly lower compared with a normal diet.

Multiple studies have shown a decrease in testosterone levels following intermittent fasting using the TRF method. However, this is not conclusive, and more studies may be needed.

Can you fast while on testosterone replacement therapy?

There are pieces of evidence that demonstrate that intermittent fasting decreases testosterone levels. So, while testosterone replacement therapy (TRT) aims to supplement testosterone levels, keep in mind that intermittent fasting may temporarily suppress natural testosterone production.

The method of testosterone administration is also worth considering. Injections, patches, and gels deliver testosterone directly into the bloodstream and do not rely on digestion. Therefore, they do not interfere with fasting.

It is essential to consult with your healthcare provider before starting any new diet or fasting regimen, especially if you are on TRT. They can provide personalized advice based on your specific health condition and treatment plan.

Other hormones that may be affected by intermittent fasting

Intermittent fasting can influence several other hormones, which play vital roles in various bodily functions. These hormones include:

• Insulin: Fasting lowers insulin hormone levels, which may improve insulin sensitivity and help with weight management and metabolic health. Lower insulin levels mean that the body is more efficient at using stored fat for energy, which can aid in weight loss and reduce the risk of type 2 diabetes.
• Cortisol: Fasting, including short-term and prolonged protocols, increases cortisol levels. This stress hormone exhibits altered secretion patterns during fasting, with peak levels shifting from morning to afternoon in some cases.
• Thyroid hormones: Despite a significant drop in triiodothyronine (T3) levels during fasting, thyroid stimulating hormone (TSH) levels generally remain stable. This suggests that the body's primary thyroid control mechanism remains unaffected by short-term nutrient deprivation.
• Growth Hormone: Fasting has been shown to increase levels of growth hormone, which plays a role in fat metabolism and muscle growth. Higher levels of growth hormone can enhance the body’s ability to burn fat and build muscle, contributing to improved body composition and physical performance.

Benefits of intermittent fasting

Intermittent fasting offers various health benefits beyond potential hormonal changes. Some of the key benefits include:

• Improved insulin sensitivity: Intermittent fasting can help regulate blood sugar levels, making it a promising approach for individuals with diabetes or prediabetes. Improved insulin sensitivity means that the body can manage blood sugar levels, reducing the risk of insulin resistance and metabolic syndrome.
• Weight loss: By reducing overall calorie intake, intermittent fasting can contribute to weight loss. This is done by creating a calorie deficit and enhancing the body’s ability to burn fat for energy.
• Reduced inflammation: IF can help minimize chronic inflammation associated with obesity by promoting cellular cleanup (autophagy) and supporting immune function. This may also reduce the risk of heart disease.
• Enhanced emotional well-being: Generally, IF may improve mood and reduce symptoms of depression.
• Brain health and longevity: IF may promote brain health by enhancing cognitive function and protecting against neurodegenerative diseases. Additionally, IF can extend lifespan and promote healthy aging by reducing oxidative damage and improving cellular repair mechanisms.

While intermittent fasting has several benefits, it’s not without risk of adverse effects. Some potential side effects of IF include low bone density, compromised immune system, hypoglycemia in patients with diabetes, and insufficient nutrients in pregnant and breastfeeding women.

Best practices for fasting

If you are planning on fasting, here are some best practices to keep in mind:

• Stay hydrated by drinking lots of water, herbal teas, and coffee, but avoid sugary drinks and excessive caffeine.
• Eat a balanced diet rich in vitamins, minerals, and macronutrients.
• Listen to your body and stop fasting if you feel unwell.
• Start gradually so that your body can adapt to the new eating pattern.
• Try as much as possible to get adequate sleep—at least 8 hours of quality sleep.
• Do not overeat or consume excessive amounts of unhealthy foods during your eating windows.
• Most importantly, consult your healthcare providers before starting IF, especially if you have underlying health conditions, such as diabetes, heart disease, or eating disorders.

Final words

While intermittent fasting offers potential benefits like weight loss, improved insulin sensitivity, and reduced inflammation, it also has drawbacks such as potential nutrient deficiencies and hormonal imbalances. 

Testosterone levels can decrease during intermittent fasting, and while TRT can offset this, careful monitoring is essential. 

Other hormones affected by intermittent fasting include insulin, cortisol, and thyroid hormones. Each hormone plays a crucial role in overall health, and their fluctuations during IF should be considered. 

It is important to approach IF with caution, considering individual health conditions and consulting a healthcare provider before starting any new dietary regimen.