How testosterone affects fat loss

Written by:

Wesley Lo

Wesley Lo

Wesley is a health and fitness coach in Hong Kong, with a passion for finding ways to improve health, longevity and athletic performances.


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We hear lots of talk about testosterone, but how many of us understand what work it does for our bodies? Especially during the fat loss process? How many of you have tried to go for a calorie deficit diet, training often, but still not able to lose the last layer of lower belly fat?

Here is why.

Testosterone is primarily a male sex hormone – although, women also produce small amounts of testosterone in the ovaries. Also known as the “anti-aging hormone”, testosterone affects the brain, bones and muscle masses, fat distributions, genital tissues, and sexual behaviours. Testosterone deficiency is found to be a predisposing factor for premature death. Conversely, a higher testosterone level links to a longer lifespan in men.

The reference range for a highly sensitive testosterone level in men aged 16–60 should be 10–38 nmol/L. The most reliable way for men to determine testosterone levels is to take a sample blood test between 7 am and 12 noon, as the levels are lower in the afternoon and evening. The optimal testosterone level for men should lie on the top half of the reference range – the closer to the upper limit, the better. Levels below 15 could be indicative of subclinical hypogonadism, which may require treatments.

Besides testosterone, there is another hormone called estrogen. The two work together in a yin yang process to make body functions balance. When the testosterone level is high, estrogenic levels will go down and vice versa.

In the scenario of muscle gain and fat loss, these two hormones are important. When we have a higher range of testosterone, we naturally will increase the muscle mass and reduce fat storage even if we don’t train. When oestrogen levels are high, we decrease muscle mass and store body fat even if we train a lot. It is important to know our testosterone level if we want to gain muscle and lose fat effectively. It is optimal to have a higher testosterone level, of say 36, than a lower level of for example 12.

There are many natural ways to optimise testosterone levels without using drugs. For example, healthy food intakes, effective exercise protocols, supplements, quality sleeps and stress management. Unfortunately, some people still take a risk and use anabolic steroids to boost testosterone without a doctor’s prescription or supervision. This may increase the risk of cancer, hair loss, damaged liver function, rough skin condition, acnes, heart stroke and depression.

If you observe your diet, training and lifestyle are adequate but still are not able to reach the result you want, it could be a time for you to conduct a blood test to find out the testosterone level and consult a professional.