Having a high body fat percentage is bad news for men. As your body fat increases past normal ranges, your risk for disease of the heart, brain, and bones all increase dramatically.

But what does the research say about the relationship between how much fat you have and your testosterone levels?

What Is Body Fat?

Before we get started I think that it’s important to make it clear how dietary fat is different than body fat. 

Body fat or “adipose tissue” is how the body stores energy over time. An excess of calories (energy) over time, whether it be from carbs, protein, or fat, leads to an increased storage in adipose fat tissue.

Two key types of fat are:

• Visceral fat (around organs)
• Subcutaneous fat (under the skin)

There are other types of fat such as ectopic fat (in the liver, heart, pancreas, and skeletal muscle), marrow fat, white and brown adipose tissue, etc…

To keep things simple however, visceral fat (what you can’t see) and subcutaneous fat (the stuff you hate to pinch) are the two types you’ll probably ever need to care about.

Does Having More Body Fat Actually Decrease Testosterone?

The research is conclusive that men with more body fat have less testosterone (study, study, study).

In fact, one study found a 40% increase in the frequency of low testosterone in obese men when compared to their lean counterparts. The more fat you have, the more aromatase enzyme you have. Aromatase enzyme converts testosterone into estrogens.

In a nutshell, more fat = more estrogen and less testosterone. 

More Body Fat Increases Leptin

Leptin is a satiety hormone, which is released from fat cells to signal to the hypothalamus in the brain that the body has enough energy coming in. Since leptin is released from fat cells, it makes sense that the fatter you get, the more leptin you produce.

Research has shown that there is a strong association between biologically active leptin and testosterone. Low leptin levels signal to your Leydig cells in your testicles to produce less testosterone.

A randomized controlled trial concluded that for hypogonadal men (those with low testosterone), taking exogenous testosterone decreased leptin.

More Belly Fat Neutralizes DHT

Dihydrotestosterone (DHT) is the most potent androgen in men. Approximately 5% of total testosterone converts into DHT through 5α-reductase.

Some men try to lower their DHT levels (usually for hair loss), but the truth is that DHT isn’t something you want to reduce.

DHT is responsible for: 

• Body hair and facial hair growth
• Sex drive and erection quality
• Mood
• Lower chance of Alzheimer’s disease
• Body fat
• And much more…

Researchers in Canada looking at subcutaneous fat and abdominal fat concluded that in subcutaneous fat, a high conversion of DHT into 3β-Androstanediol (3β-diol) occurs.

Simply put, the more fat you have, the more DHT turns into the less potent 3β-diol.

The Problem With Visceral Fat

Fat around your organs (also known as visceral fat) is dangerous and is correlated with a number of diseases. The more fat you have, the more fat around your organs (visceral fat) you will most likely also have.

We know that increasing testosterone (even by as little as 30%) can significantly decrease visceral fat (study, study). In one study of Japanese-American men, low serum testosterone levels were a predictor of more visceral fat.

You can reduce visceral fat by: 

• Decreasing your body fat percentage
• Keeping stress (cortisol) levels low
• Exercising (preferably HIIT and strength training)
• Limiting alcohol and just drinking it in moderation
• Sleeping well (between 7-9 hours)
• Cutting out trans fats

A Very Low Body Fat Decreases Testosterone Levels

Yes, it does, but a caloric deficit (consuming less energy that you need) is necessary if you’re trying to lose body fat.

Research shows that a caloric deficit increases cortisol and decreases testosterone, especially when endured long-term.

A deficit in energy is essentially a stress on the body, and so the increase in cortisol is expected.

It’s important to understand how your body reacts to small or large caloric deficits.

An aggressive fat loss tends to be defined as anything over a 25% deficit. Contrary to most advice, the research supports the effectiveness of aggressive fat loss (study, study, study).

What’s the goal when losing fat? 

The goal is to drop your calories as low as possible while retaining as much muscle as possible and not feel like crap in the process.

If you’re under 15% body fat, then a more gradual approach may be better. Your chance of losing muscle mass in a caloric deficit when you’re lean increases.

It’s worth noting that a small caloric deficit of 15% seems to have no effect on testosterone levels.

To keeps things simple:

• If you’re fat, then do an aggressive cut (20-30% caloric deficit).
• If you’re lean, then take your time and do it more gradually (5-15% caloric deficit).

Yes, if you have a lot of body fat, you can do gradual fat loss and vice versa. The above is simply what works well for most.

Conclusion 

Overall, the research is pretty clear that excessive body fat not only increases your risk of dying young, but also decreases testosterone levels. It’s not looking good for the fat activists out there…

There are some potential advantages to having more body fat (like having better leverages for certain exercises like the bench press), but in terms of testosterone, the cons outweigh the…well, there aren’t any pros.

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