Belly Fat Linked To Low Testosterone Levels
Although testosterone is often considered a muscle-building hormone,
it also plays an important role in helping you stay lean.
In fact,
researchers from the University of Washington have shown that men
with low testosterone levels appear to
be at greater risk of developing belly fat [1].
Belly fat and testosterone
More than 100 Japanese-American men took part in the research.
A number of measurements, including total body fat, belly fat and testosterone
levels, were taken at the start of the study. The same measurements
were taken again seven years later.
The research team found a link between testosterone levels at the
start of the study and changes in belly fat (also known as visceral fat). In other words,
belly fat increased to a greater extent in the men who started the
study with low testosterone levels.
There are two main types of fat in the stomach area.
- Visceral (pronounced viss-er-al) fat is stored deep inside your body. It surrounds and protects your internal organs. If you've ever seen someone who seems to have very "hard" belly fat, it's visceral fat that's mainly responsible.
- Subcutaneous (pronounced sub-cue-tain-ee-us) fat, on the other hand, is stored just under your skin. It's the stuff that wobbles when you jump up and down.
Not only does it look bad, visceral fat precedes the development of type II diabetes in Japanese Americans. It's also been linked to high blood pressure and heart disease.
Further evidence to show that low testosterone levels make it harder to burn belly fat comes from a group of researchers based at Canada's McMaster University [3].
A group of healthy men were given monthly injections of a drug that suppressed their natural production of testosterone. They were then given one of five doses (25, 50, 125, 300, or 600 milligrams per week) of testosterone enanthate for 20 weeks. This allowed the researchers to see what effect testosterone had on belly fat levels.
The study had a number of unique features, one of which was that they used magnetic resonance imaging (MRI) to examine changes in body composition. Previous studies of testosterone supplementation used DEXA scan alone, which is not as accurate as MRI.
The figure below shows the changes in abdominal fat with the five different doses of testosterone.
As you can see, the men given the lowest dose of testosterone (25 milligrams per week) actually gained belly fat. Those given the highest dose (600 milligrams per week) lost both subcutaneous AND visceral belly fat.
How does testosterone affect belly fat?
Just like a car, your fat cells have a series of brakes and accelerators. The
parts of a fat cell that accelerate the release of fat are called beta
receptors, while the parts of a fat cell that put the brakes on fat loss are
known as alpha receptors.
Beta receptors help fat loss because they increase the rate at which stored fat is broken down, as well as increasing blood flow in fat tissue. In contrast, alpha receptors hinder fat loss, slowing the flow of fat out of a fat cell.
The distribution of brakes and accelerators on each fat cell explains (in part anyway) why certain parts of your body lose fat faster than others.
If a fat cell has more beta receptors, it will release stored fat more quickly than one with fewer beta receptors. And that's where testosterone appears to help. By increasing the number of beta receptors, testosterone makes it easier to lose stored fat.
What's more, testosterone can also limit the storage of fat. When fat cells are exposed to testosterone in a test tube, the activity of lipoprotein lipase — an enzyme that promotes fat storage — is dramatically reduced.
About the Author
 Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.
If you want better, faster results from the time you spend in the gym, click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.
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Reference
1. Tsai, E.C., Boyko, E.J., Leonetti, D.L., & Fujimoto, W.Y.
(2000). Low serum testosterone level as a predictor of increased
visceral fat in Japanese-American men. International
Journal of Obesity and Related Metabolic Disorders, 24,
485-491
2. De Pergola, G. (2000). The adipose tissue metabolism: role of testosterone and
dehydroepiandrosterone. International Journal of Obesity and Related Metabolic Disorders, 24, S59-63
3. Woodhouse LJ, Gupta N, Bhasin M, Singh AB, Ross R, Phillips J, Bhasin S. (2004). Dose-dependent effects of testosterone on regional adipose tissue distribution in healthy young men. Journal of Clinical Endocrinology and Metabolism, 89, 718-726
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