Calorie Restriction and Testosterone: Is There A Connection?

This post is going to investigate the link between calorie restriction and testosterone levels.

When most people think of testosterone, they often think about athletes using testosterone injections or men undergoing testosterone therapy.

However, testosterone is a hormone that your body can produce all by itself without the use of injections.

And this hormone is not just responsible for muscle building, but also plays a role in sexual libido, mental well-being, and bone strength.

With optimal levels of testosterone being linked to many physical and mental benefits, it makes a lot of sense to avoid anything that can lower your testosterone levels.

So with that being said let’s look at how calorie restriction affects testosterone levels.

Calorie Intake and Testosterone Levels

One of the best ways for men to keep their testosterone levels optimal is to lose some weight – or more specifically lose body fat.

This will help to lower the enzyme aromatase in the body, which is an enzyme that converts testosterone into estrogen.

Many studies have collectively proven that a high body fat percentage in men does lead to lower testosterone levels in the body. (study, study, study)

But here’s the problem:

To lower body fat levels we have to restrict calories and create a calorie deficit otherwise we will not burn body fat.

However, long-term calorie restriction can lead to testosterone levels plummeting, sometimes even as low as a castrated man.

All the research shows that extra body fat reduces testosterone levels – reducing body fat can increase testosterone levels – but calorie restriction can lower testosterone levels. 

So with all this information, it might seem as though there’s no way to reduce calories and lose weight without lowering testosterone levels in the process.

But here’s the deal:

Most of the research has shown that the calorie restriction has to be very extreme to significantly lower testosterone levels.

In fact, there are even studies which show that when there is a 15% reduction in overall calories consumed there is no reduction in testosterone levels.

So this research shows us that mild dieting does not have a major impact on testosterone levels.

However, when men diet hard over a long period of time, along with intense training in the gym the results are not so pretty.

The military even did some research on soldiers that looked at the effects of 8 weeks of extreme stressors such as – a low-calorie diet, hard training, and lack of sleep.

At the end of the 8 week period, the soldier’s testosterone levels had dropped to near castrate levels.

One of the reasons that this happens is because when the body does not get enough calories it begins to produce high amounts of stress hormones.

And when stress becomes excessive and begins to rise in the body for a prolonged amount of time, it can alter and lower testosterone levels.

Another reason that T levels can begin to decline is that when the body does not get adequate calories, it can hold back certain processes of the body that are not critical for survival.

One of the processes that can be put on hold is testosterone production and this is the reason why testosterone levels can decline over a long period of time.

But the thing to remember about this military research is that the soldiers in the study experienced very severe stressors and over a long period of 8 weeks.

This is not what the average person will have to experience but nevertheless, it does highlight the need to look at how hard we are training and how much sleep we are getting while we are dieting and trying to lose weight.

Another interesting thing to remember is that after a long period of hard dieting a short re-feed is enough to bring testosterone levels back to normal.

In fact, there was even a study involving men who did not eat any food for 10 days. What the researchers discovered was that while the levels of testosterone did slowly begin to lower, it was only on the 9th day of the fast that testosterone levels began to lower significantly.

When the fast was over the subjects were allowed to eat 1500 calories each day. As expected testosterone levels began to rise.

But what surprised the researchers the most, was that after this re-feed the men’s testosterone levels were higher than before they started the fast.

The reason that this happens is because after fasting the body becomes more sensitive to testosterone. This was proven in a study which showed how fasting for 12-56 hours increases the body’s sensitivity to testosterone.

The good news is that we can get this increase in sensitivity without having to fast for long periods of time. This is because studies have shown that short-term fasts can trigger this same increase in androgen sensitivity.

Bottom Line: These findings show that fasting for (56 hours and beyond) can slowly begin to lower testosterone. However, short-term fasting “IF style” will not affect testosterone levels but can, in fact, increase testosterone sensitivity while also helping lower body fat.

This is the reason why Intermittent fasting for short periods is the best way to get lean and also get the testosterone boosting benefits of short-term calorie restriction.

Brad Pilon is well known as one of the leading experts on Intermittent Fasting – I highly recommend anyone wanting to know about his approach to intermittent fasting to take a look at his book Eat Stop Eat.

I hope this article has given you some information about the link between calorie restriction and testosterone levels.

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