In short
Extra fat lowers testosterone, and low testosterone makes it easier to gain fat. Losing weight raises testosterone again.
On this page
Weight and testosterone push each other in the wrong direction. Carrying extra fat, especially around the middle, lowers testosterone. Lower testosterone makes it easier to gain fat and lose muscle. Losing weight raises testosterone again.
How extra weight lowers testosterone
- Fat tissue converts testosterone to oestrogen. More fat means more conversion.
- The brain’s signal drops. Obesity dampens the hormones from the pituitary gland that tell the testes to make testosterone.
- The carrier protein falls. SHBG, which carries testosterone in the blood, is lower in men with obesity and insulin resistance, so the total testosterone on a blood test reads lower.
- Sleep apnoea adds to it. Broken sleep lowers testosterone on its own.
How much difference does weight loss make?
A meaningful one. When studies are pooled, men who lose weight through diet raise their testosterone by around 3 nmol/L on average, and men who lose more through surgery raise it by considerably more. The more weight lost, the bigger the rise.
Want a plan that fits your health?
An Australian GP can check the basics and work out a realistic plan with you, by phone or video.
Why this matters for diagnosis
A low testosterone result in a man with obesity is often a consequence of the weight, not a disease of the testes or pituitary. Australian endocrinology guidance treats these differently. For the first, the priority is weight, sleep and metabolic health. For the second, testosterone treatment is clearly indicated. A GP sorts out which applies with two morning blood tests and the pituitary hormones LH and FSH.
Does testosterone treatment cause weight loss?
In men with confirmed low testosterone, treatment tends to reduce fat and increase muscle modestly. It isn’t a weight loss treatment, it isn’t appropriate for men with normal levels, and it switches off sperm production while you’re on it.
What to do first
- Measure your waist. See waist circumference for men.
- Ask about sleep apnoea if you snore and wake tired.
- Get the basics checked. Blood pressure, blood sugar and cholesterol.
- Test testosterone properly if you have symptoms. See testosterone test in Australia.
Next step: talk to a GP
Request an appointment and we’ll be in touch to arrange a time. A consultation doesn’t guarantee a prescription.
References
- Corona G, et al. Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: a systematic review and meta-analysis. European Journal of Endocrinology. 2013.
- Yeap BB, et al. Endocrine Society of Australia position statement on male hypogonadism. Medical Journal of Australia. 2016.
- Healthy Male: Androgen deficiency
This guide is general information, not medical advice. It doesn’t replace a consultation with a doctor who knows your history. In an emergency, call 000.