Should You Eat More Fat to Raise Your Testosterone?

Today we’re diving into a hotly debated topic in fitness—high-fat versus low-fat diets and their impacts on testosterone levels. While nutrition trends come and go, this topic consistently resurfaces because of the potential connection between dietary fat and hormone health. Testosterone, in particular, plays a crucial role in muscle growth, body composition, and overall well-being, making it an essential subject for anyone looking to optimise their fitness.

But does altering fat intake really have the power to impact your testosterone levels enough to influence your gains in the gym? The answer, as always, is more nuanced than a simple yes or no, as explained by Dr Layne Norton in a recent video.

Dr Layne Norton is a scientist, pro natural bodybuilder, raw elite powerlifter, and physique coach, among other things. He received his BS in Biochemistry, and his PhD in Nutritional Sciences. Besides being a coach, he also commands his YouTube channel in which he talks about science and fitness intertwined, sometimes breaking down scientific studies that come out so people can make better-informed decisions in their fitness journey.

Based on his expertise, who provides excellent evidence-based insights, we’ll explore some key findings from a meta-analysis comparing high-fat (over 40% of daily caloric intake) and low-fat (around 20%) diets. The research examines the effects of these diets on testosterone, free testosterone, and other markers such as sex hormone-binding globulin and DHT over periods ranging from two to ten weeks. While it may seem intuitive that a diet higher in fat would lead to a significant boost in testosterone, the real question is: does this actually translate into better body composition or muscle growth? That’s what we’re here to find out.

In this article, we’ll break down the science behind how different fat intakes impact testosterone, explore the mechanisms that matter most for muscle growth, and give you actionable advice on how to manage your diet for optimal outcomes. Remember, it’s not just about the mechanisms behind testosterone—it’s about the actual results they deliver when it comes to your health and fitness.

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High-Fat Versus Low-Fat Diets and Testosterone: The Science

Recent research has shown that a higher-fat diet can indeed lead to a slight increase in testosterone levels compared to a low-fat diet. On average, we’re talking about an increase of 5-15%. While that might sound significant, the reality is more complex. Testosterone is just one part of a vast biochemical system that influences muscle hypertrophy and body composition. It is far from the only factor that drives muscle growth.

For example, insulin, a hormone influenced by carbohydrate intake, plays a crucial role in muscle protein synthesis. It stimulates muscle growth by preventing muscle protein breakdown, a key factor often overlooked in favour of testosterone’s role in hypertrophy. Therefore, if you’re consuming a higher-fat diet and reducing carbohydrates, you’re also limiting insulin production, which could, in turn, slow muscle protein synthesis. This factor alone suggests that despite small increases in testosterone, higher-fat diets may not lead to superior gains in muscle mass.

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The Impact of Testosterone on Muscle Growth

So, why doesn’t a 5-15% rise in testosterone translate into significant changes in body composition? The simple answer is that the increase isn’t large enough to create noticeable differences. In the context of resistance training and controlled caloric intake, studies have shown minimal differences in body composition outcomes between individuals following high-fat versus low-fat diets.

Testosterone does contribute to muscle growth, but its influence operates alongside numerous other hormones and processes. Just because one hormone rises doesn’t mean the entire muscle-building system gets an immediate boost. The body is much more complex than that. For instance, a higher carbohydrate intake will increase insulin levels, which aids in muscle growth by promoting protein synthesis and inhibiting muscle protein breakdown.

Moreover, testosterone levels naturally fluctuate throughout the day and can be influenced by many factors beyond diet, including sleep, stress levels, and training intensity. The relatively small changes in testosterone seen in response to dietary fat intake are often too minor to outpace these other influences.

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Outcomes Over Mechanisms: The Big Picture

One of the biggest takeaways from this discussion should be the focus on outcomes rather than mechanisms. When evaluating diet and its influence on performance, body composition, or general health, it’s important to remember that outcomes are driven by a multitude of factors working together, not just a single hormone or process. A great example of this is aspirin, which, despite activating both procoagulant and anticoagulant pathways, still works effectively as a blood thinner. The sum of the processes determines the overall effect.

Similarly, when it comes to diet, a small increase in testosterone isn’t the only factor that should dictate your choices. Whether you prefer a high-fat or low-fat diet, the most critical considerations are overall caloric intake, protein consumption, and fibre intake. These factors have a far more significant impact on muscle growth, fat loss, and health outcomes than modest shifts in testosterone.

Additionally, personal preference and sustainability play massive roles in dietary adherence. If a higher-fat diet helps you stick to your nutrition plan, that’s great. But if you find that lower-fat, higher-carb meals fuel your workouts better and improve your recovery, that’s the approach you should prioritise.

High-Fat Versus Low-Fat Diet: The Verdict

So, what’s the bottom line on high-fat versus low-fat diets and their effects on testosterone and muscle growth? Yes, high-fat diets can lead to modest increases in testosterone, but the impact on body composition is negligible. The most important factors for muscle growth remain consistent—caloric control, sufficient protein intake, and adequate carbohydrate levels to support performance and recovery.

The key is to focus on the big picture: your total caloric intake, macronutrient distribution, and how well you can stick to your diet in the long term. If you enjoy higher-fat foods, that’s perfectly fine as long as you hit your macronutrient targets and control your overall calories. If you prefer lower-fat, higher-carb diets because they fuel your workouts better, that’s equally valid.

Conclusion: Prioritise What Matters

At the end of the day, your diet should be structured around what works best for you, your goals, and your lifestyle. While small changes in testosterone levels may seem important, the actual outcomes—how you perform in the gym, your ability to maintain muscle mass, and your overall health—are what truly matter. Focus on what will help you stay consistent with your diet and training, and the results will follow. Whether you’re a high-fat or low-fat advocate, the most crucial elements are adherence, balance, and optimising for the outcomes that count.

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