Some men believe that testosterone may assist in fat loss.
This hormone is responsible for some of the typical male characteristics. It also promotes muscle growth in both genders.
Most men are full of testosterone. However, a few suffer from a deficiency, a problem that seems to predispose them to excessive fat gain.
This article discusses the potential role of this hormone in weight loss and obesity.
What Is Testosterone?
Testosterone is the most important male sex hormone. It is mainly produced by the testicles in men and ovaries in women.
Hormones are messenger molecules that play a vital role in all body systems. They are released into the bloodstream, which carries them to their target cells.
When hormones come in contact with compatible cells, they bind to receptors on their surface and affect their function.
Testosterone’s main role is to promote male characteristics like a deeper voice, increased muscle mass, stronger bones and facial and body hair growth.
Adequate levels are also essential for the maturation of sperm cells and the maintenance of male fertility.
Unsurprisingly, testosterone levels are much higher in men than in women. Yet the hormone plays several vital roles in women, too (1).
One of its most important functions in both genders is to maintain muscle mass and promote muscle growth and bone strength. Your levels decline with age, partly explaining age-related muscle and bone loss.
Not only does deficiency suppress muscle growth and maintenance, but it may also promote weight gain.
Summary: Testosterone is the primary male sex hormone. It promotes muscle growth as well as other typical male characteristics, such as a deep voice and body hair growth.
Deficiency May Lead to Weight Gain
Testosterone promotes muscle growth. At the same time, it may suppress fat gain (2, 3, 4).
As a result, some testosterone-deficient men tend to gain fat more easily than their healthy peers (5, 6).
Muscles burn far more calories than fat tissue. Lack of muscle thus puts people at a higher risk of eating too much and storing the excess calories as fat (7).
In fact, some researchers believe that reduced muscle mass is the primary reason deficiency leads to weight gain in men (8).
Obesity itself may also suppress testosterone levels, as explained in the next chapter.
Summary: Low testosterone levels reduce muscle mass and calorie expenditure. For this reason, deficiency may promote weight gain over time.
Obesity Is Linked With Low Levels
On average, obese men have 30% lower testosterone levels than those who are normal-weight (9).
More than 70% of morbidly obese men suffer from male hypogonadism, or testosterone deficiency, a disorder characterized by abnormally low levels of this hormone. Male hypogonadism may reverse with weight loss (10).
Scientists are not entirely sure why levels are lower in obese men, but most studies point toward the following processes.
First, belly fat contains high levels of the enzyme aromatase, which converts testosterone into estrogen, the female sex hormone. This explains why obese men have higher estrogen levels than normal-weight men (11).
Second, high aromatase and estrogen activity reduces the production of gonadotropin-releasing hormone (GRH). Lack of GRH leads to lower levels of luteinizing hormone, which in turn reduces the production of testosterone (12, 13).
Put simply, excessive belly fat appears to suppress testosterone levels.
Summary: Obese men tend to have lower levels of this hormone than normal-weight men. Most research suggests that excessive belly fat reduces these levels.
Do Supplements Cause Weight Loss?
The term “testosterone supplement” can refer to three things: illicit anabolic steroids, testosterone replacement therapy and testosterone boosters.
Illicit Anabolic Steroids
Synthetic steroids related to testosterone are collectively known as anabolic steroids. The term may also refer to testosterone itself.
Some bodybuilders misuse anabolic steroids to increase testosterone beyond normal levels and boost muscle growth. Yet abusing anabolic steroids is illegal in many countries, including the US (14).
Healthy men with normal testosterone levels should not take anabolic steroids in any form, since long-term misuse can cause adverse side effects. These include sexual dysfunction, aggressive behavior, liver problems and heart disease (15, 16, 17).
Some researchers have pointed out that not all of these side effects apply to testosterone itself but rather to its synthetic derivatives. In fact, testosterone plays a valid role in the treatment of some medical conditions (18).
For instance, it is legally prescribed to normalize testosterone levels in deficient men, a treatment known as testosterone replacement therapy (19).
While valid testosterone replacement therapy may promote weight loss in obese men, anabolic steroid misuse is not a recommended weight loss strategy.
Excessive muscle mass may be difficult to maintain in the long term and unused muscles tend to turn into fat over time.
Summary: Some bodybuilders misuse testosterone or related synthetic forms. Long-term misuse may lead to serious health problems.
Testosterone Replacement Therapy
This hormone is often legally prescribed to treat testosterone deficiency (hypogonadism) or other medical conditions.
The treatment is known as testosterone replacement therapy and is performed under medical supervision. It can be administered as a supplement, skin patch, cream or injection.
There is some evidence that replacement therapy can lead to weight loss in obese patients with testosterone deficiency (20, 21, 22, 23).
One 56-week study in 100 obese men on a reduced-calorie diet found that injections improved weight loss by 6.4 pounds (2.9 kg) compared to those who didn’t receive any treatment.
While both groups lost muscle mass as well as fat mass on a low-calorie diet, testosterone caused significant muscle regain during the weight maintenance period (24).
It leads to weight loss by promoting muscle growth, which in turn increases the number of calories burned.
It may also reduce fatigue, enhance motivation and promote greater physical activity. All of these factors play a major role in weight loss (8, 25).
Keep in mind that these studies examined the effects of replacement therapy in deficient men under medical supervision.
There is no evidence that replacement therapy causes weight loss in healthy men with normal testosterone levels.
Summary: Testosterone replacement therapy promotes weight loss in obese, testosterone-deficient men.
Also known as “natural testosterone supplements,” testosterone boosters increase the natural production of this hormone within your body.
These supplements do not contain any testosterone and are usually plant-based.
Some boosters, such as ashwagandha, D-aspartic acid and fenugreek seed extract, may raise testosterone levels and improve muscle growth in men who have low levels, although the evidence is inconsistent (26, 27, 28).
However, many of the health claims associated with boosters are not supported by science. For instance, Tribulus terrestris, a supplement commonly sold as a booster, does not appear to raise levels (29).
Currently, no studies have shown significant weight loss with testosterone boosters, although some tend to reduce fat mass.
Summary: Testosterone boosters enhance the natural production of testosterone within the body. Studies suggest that certain boosters may benefit men who are deficient.
How Can You Increase Your Levels Naturally?
The main symptoms of testosterone deficiency include low libido, difficulty maintaining or developing an erection and less intense orgasms.
Other symptoms include fatigue, low mood and reduced muscle mass.
If you suspect you have low levels, a simple blood test can confirm deficiency.
Replacement therapy is the most effective treatment. However, it is controversial and has risks as well as benefits (30, 31, 32, 33).
Fortunately, there are several ways you can naturally improve low testosterone levels. A few methods are listed below:
- Strength train: Many studies show that strength training can increase your levels of this hormone (34, 35).
- Take vitamin D supplements: Vitamin D deficiency is associated with low levels. Supplements can bring levels back to normal (36, 37).
- Get adequate zinc: Deficiency in zinc may reduce levels. Eat plenty of zinc-rich foods, such as meat, nuts and seeds, to normalize your levels (38, 39).
- Get enough sleep: Poor sleep is associated with a drop in levels. In fact, getting enough sleep is one of the most important aspects of a healthy lifestyle (40, 41).
- Try ashwagandha: The medicinal herb ashwagandha, known scientifically as Withania somnifera, may improve levels and fertility (26).
- Relax and minimize stress: Chronic stress raises the levels of cortisol, a hormone that may suppress testosterone levels. A stress-free environment and relaxing pastime activities are a cornerstone of a healthy lifestyle (42).
In addition to raising your testosterone levels, the above strategies can improve your general health. Some may even help you lose weight, especially when combined with other weight loss methods.
Summary: Several strategies can improve the natural production of testosterone in the body and promote weight loss.
The Bottom Line
Adequate testosterone levels are a sign of good health.
Testosterone helps maintain muscle mass, increase the number of calories you burn and may keep you motivated to stay physically active — all of which are associated with a lower risk of weight gain and obesity.
If you suspect you may be deficient, consult your doctor for a simple blood test.
Your doctor can prescribe a testosterone replacement therapy, which is the most effective way to normalize your levels.
You can also try raising your levels naturally by losing belly fat, strength training, getting enough sleep or taking testosterone boosters like ashwagandha.