How Intermittent Fasting Affects Testosterone Levels in Men

• June 19, 2025
• Dr Luke Wee

Last updated on June 19, 2025

Intermittent fasting has become one of the most widely discussed approaches to improving health and managing weight. Beyond its metabolic benefits, many men are now asking a key question: Does fasting increase testosterone?

Testosterone plays a vital role in male fertility, strength, mood and overall wellbeing, so it’s no surprise that interest in natural ways to support hormone levels continues to grow. In this blog, we explore how intermittent fasting may influence testosterone levels in men and what current research reveals about the connection.

Understanding Testosterone in Men

Testosterone is the primary male sex hormone responsible for regulating a wide range of functions. It affects:

• Muscle mass and strength
• Bone density
• Libido and sexual function
• Mood and mental clarity
• Sperm production and fertility

Testosterone levels in men naturally decline with age, but lifestyle factors such as diet, stress and body composition can also contribute. Maintaining hormonal balance is therefore important not only for reproductive health, but for overall physical and mental wellbeing.

What is Intermittent Fasting?

Intermittent fasting (IF) refers to a structured approach to eating that alternates between periods of eating and periods of fasting. Common patterns include:

• 16:8 — 16 hours fasting, 8 hours eating
• 5:2 — normal eating for five days, reduced intake for two non-consecutive days
• 24-hour fasts — once or twice a week

Rather than focusing on what you eat, intermittent fasting focuses on when you eat — and how that timing may influence metabolism, fat storage and hormone production.

Fasting and Testosterone: What the Science Says

Several studies have explored the relationship between fasting and hormone levels, particularly testosterone. While findings vary, some consistent patterns have emerged:

• Short-term fasting (up to 24 hours) may result in a temporary increase in luteinising hormone (LH) — a key hormone that signals the testes to produce testosterone.
• Some research suggests that intermittent fasting can help reduce insulin resistance and support metabolic health, which may indirectly support testosterone production.
• Other studies show improved body composition (including reduced body fat) following fasting, which is linked to healthier testosterone levels.

It’s important to note, however, that the effects of fasting can depend on several factors, including age, body composition and fasting duration. Long-term calorie restriction or excessive fasting may have the opposite effect if not properly managed.

How Fasting May Influence Testosterone

While intermittent fasting may not boost testosterone in every case, several mechanisms could explain its potential impact:

• Lower insulin levels: High insulin can suppress testosterone; fasting helps reduce circulating insulin.
• Fat loss: Excess body fat, particularly abdominal fat, is associated with lower testosterone. Fasting supports fat metabolism.
• Inflammation reduction: Chronic inflammation can negatively affect hormone balance. Fasting may help reduce inflammatory markers.
• Improved LH secretion: Short-term fasting may stimulate LH, which supports testosterone synthesis.

Reproductive Health and Hormonal Balance

Testosterone plays a key role in male reproductive health, including the production of sperm. While intermittent fasting testosterone studies don’t always directly measure fertility outcomes, improvements in hormonal balance, metabolic function and weight management may contribute to overall reproductive health.

For men considering or having undergone a vasectomy, testosterone levels are typically unaffected by the procedure itself. However, maintaining hormonal health remains important as part of a broader focus on wellbeing.

Risks and Considerations

While intermittent fasting for hormone health shows promise, it’s not suitable for everyone. Potential risks include:

• Increased stress hormones like cortisol during prolonged fasts
• Reduced energy availability if fasting windows lead to inadequate food intake
• Hormonal disruption in men with already low body fat or high training loads

It’s important to adopt fasting as part of a sustainable, balanced lifestyle rather than an extreme or short-term measure.

Supporting Testosterone While Fasting

Fasting alone isn’t a guaranteed solution for low testosterone. To support optimal hormone balance, consider the following:

• Eat a balanced diet rich in healthy fats, protein and micronutrients during eating windows
• Incorporate resistance training, which has been shown to naturally support testosterone
• Manage stress through relaxation techniques or regular sleep
• Avoid prolonged fasts unless under professional supervision

Final Thoughts

So, does fasting increase testosterone? The answer is: it might, especially when combined with healthy lifestyle habits. Intermittent fasting can support a more balanced hormonal environment, but results vary between individuals. For men seeking ways to optimise hormone levels or improve overall health, fasting could be a valuable tool when used correctly.

If you’re exploring options around reproductive health or long-term contraception, our team at The Cooper Clinic is here to help. Learn more about our vasectomy procedures and book a consultation to discuss what’s right for you.

How to book a vasectomy appointment

• Fill out our online booking form
• Call us: 0800 884 408
• Email us: info@thecooperclinic.co.nz

Frequently Asked Questions

Can intermittent fasting boost testosterone levels?

Intermittent fasting may support testosterone production indirectly by reducing body fat and improving insulin sensitivity. However, results vary between individuals.

How does fasting affect male hormones?

Fasting influences hormones such as insulin, cortisol and luteinising hormone (LH), which can collectively impact testosterone levels depending on fasting duration and energy intake.

Is intermittent fasting good for testosterone production?

It can be, especially in overweight men, as fat loss and better metabolic health are associated with healthier testosterone levels. Long-term fasting without adequate nutrition may have the opposite effect.

How long does it take for intermittent fasting to increase testosterone?

There’s no universal timeline. Some men may see hormonal changes within weeks if fasting improves weight and metabolic function, but individual responses vary.

Does skipping breakfast lower testosterone?

Skipping breakfast alone is unlikely to lower testosterone significantly. However, consistent under-eating or stress from fasting could negatively affect hormone balance over time.