What Is Low Testosterone (Low T)?

Low testosterone, often called "Low T", is a condition where the body doesn't produce enough of the hormone testosterone. Testosterone is important for things like sex drive, muscle growth, energy levels, and mood. While it’s more common as men get older, low testosterone can affect adults of any age.

What Does Testosterone Do in the Body?

Testosterone is a hormone mainly made in the testicles. It helps control:

Sex drive (libido)
Erections
Muscle strength and bone density
Body hair growth
Energy levels and mood
Fertility and sperm production

In short, testosterone plays a key role in many aspects of male health and wellbeing.

What Are the Signs of Low Testosterone?

Common symptoms of Low T include [1]:

Low sex drive or reduced interest in sex
Trouble getting or keeping an erection
Feeling tired all the time
Low mood or feeling down
Loss of muscle and strength
Increased body fat
Reduced beard or body hair growth
Problems with focus or memory

What Causes Low T?

Low testosterone levels can be caused by [2]:

Ageing (levels naturally fall from around age 30)
Injury or disease affecting the testicles
Problems with the pituitary gland (which helps control hormones)
Obesity or being very overweight
Certain medications, like steroids or cancer treatments
Chronic illnesses such as diabetes or liver disease

How Is Low Testosterone Diagnosed?

A doctor will usually check your symptoms and take a blood test to measure your testosterone levels. The test is usually done in the morning when hormone levels are highest. If levels are low, further tests may be needed to find out the cause.

Can Low Testosterone Be Treated?

Yes. If your testosterone is found to be low and causing problems, treatment may be offered. This is called testosterone replacement therapy (TRT). Options include:

Injections (weekly or longer-lasting)
Gels or creams applied to the skin
Patches worn on the skin
Implants under the skin

TRT can help improve mood, energy, sex drive, and strength. But it's not suitable for everyone, and it may affect fertility. Always speak to a healthcare professional before starting any hormone treatment.

Can Lifestyle Changes Help?

Yes. Even without medication, some changes can support testosterone levels:

Regular exercise, especially strength training
Healthy diet with plenty of protein and healthy fats
Getting enough sleep
Maintaining a healthy weight
Reducing stress and limiting alcohol

Key Takeaways

Low testosterone (Low T) happens when the body doesn’t make enough of the hormone.
It can affect mood, energy, sex drive, muscle strength, and overall wellbeing.
Common signs include tiredness, low libido, weight gain, and mood changes.
Blood tests can confirm Low T, and treatment options like testosterone therapy are available.
Healthy lifestyle habits can also support hormone balance naturally.

Note: If you think you have low testosterone, speak to your GP or a hormone specialist. Don’t self-diagnose or use supplements without medical advice.

Sources

[1] Sizar O, Leslie SW, Schwartz J. Male Hypogonadism. [Updated 2024 Feb 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532933/

[2] Halpern JA, Brannigan RE. Testosterone Deficiency. JAMA. 2019;322(11):1116. doi:10.1001/jama.2019.9290

Low testosterone (Low T)