Does Losing Weight Increase Testosterone? What Studies Show

Key takeaways

• Across 44 studies, total testosterone rose by about 2.5 nanomoles per liter after a low-calorie diet and by about 7.2 nanomoles per liter after bariatric surgery.⁸
• In moderate obesity, lower SHBG is the main reason total testosterone is low.⁶⁹
• The amount of weight lost was the strongest predictor of how much testosterone rose.³
• Up to 30 percent of low results come back normal on a repeat test.⁹
• In randomized trials, testosterone treatment did not reduce body weight.⁶

Does losing weight increase testosterone?

Yes. In men with obesity, losing weight raises testosterone, and more weight lost goes with a bigger rise. Across 44 studies, total testosterone rose by about 2.5 nanomoles per liter, about 70 nanograms per deciliter, after weight loss from a low-calorie diet and by about 7.2 nanomoles per liter, about 210 nanograms per deciliter, after bariatric surgery.⁸

Why does obesity lower testosterone?

Obesity is the condition most strongly linked to lower testosterone in men. Researchers describe two main routes.⁶

Lower SHBG. Most testosterone in the blood travels bound to a carrier protein called sex hormone binding globulin, or SHBG. Obesity lowers SHBG, so a standard total testosterone test reads lower. In moderate obesity, this is the main reason total testosterone is low. The Endocrine Society names obesity among the conditions that alter SHBG and recommends measuring free testosterone in those cases.⁶⁹²

Signals from the brain. In more severe obesity, the brain's signal to the testes can be genuinely turned down. This is likely driven by inflammation and changes in leptin signaling, and made worse by related conditions.⁶

You may read that fat tissue converts testosterone into estrogen and that this is the main cause. The evidence for that is less settled. One review says the role of estrogen feedback, in its words, requires further study, and another says estrogen and inflammation show only modest links to testosterone and no convincing causal effect.⁶⁹

Related conditions matter too. Men with type 2 diabetes have total testosterone about 57 to 86 nanograms per deciliter lower on average than men without it.⁹

Does low testosterone cause weight gain?

The link runs both ways, but not equally. Obesity has a larger effect on testosterone than testosterone has on body fat. Low testosterone is tied to diabetes through a two-way relationship with belly fat and muscle.⁶⁴

How much does testosterone go up when you lose weight?

The size of the rise tracks how much weight is lost.⁸³

A 2013 meta-analysis of 24 studies found the same pattern. Both diet and surgery raised total and unbound, or free, testosterone. Surgery raised it more, and the amount of weight lost was the strongest predictor of the rise. Weight loss also lowered estradiol and raised the pituitary hormones that drive the testes. The 2024 analysis found larger gains in men who started with a higher BMI or lower SHBG and testosterone.³⁸

Gains from lifestyle changes alone are usually modest. After weight loss from a very low calorie diet, the improvements held long term as long as the weight was not substantially regained.⁶⁵⁹

Should you test testosterone while you're losing weight?

Timing matters. An expert review in the Journal of Clinical Endocrinology and Metabolism says testosterone should not be retested during the active phase of cutting calories. Levels may dip for a while and tend to improve for good once eating is more balanced and weight loss has leveled off.⁹

That fits other research. Eating less energy than you use, over days or months, can lower testosterone through the brain's control of the testes. This effect is functional and generally reverses once energy balance is restored.⁷

A single low reading also isn't a diagnosis. Up to 30 percent of low results come back normal on a repeat test. Both major US guidelines call for repeat morning tests and symptoms before a diagnosis.⁹²¹⁰¹

If you are in the middle of losing weight and a test comes back low, it is worth telling your doctor about the timing.

Is low testosterone from obesity real hypogonadism?

Experts disagree on how to label it.⁹⁶⁵

Whether any treatment fits a particular man is a decision for him and his doctor.

• One group uses the term pseudo-hypogonadism of obesity. When testosterone and SHBG are low together and the pituitary hormones LH and FSH are normal, they consider the hormone system to be working normally, and they say testosterone treatment is not indicated.⁹
• Another review says more severe obesity can cause genuine suppression of the system. It still says testosterone treatment cannot be routinely recommended for men with obesity-related low testosterone, and that weight loss and treating related conditions come first.⁶
• A third review says treatment may be considered for men with significant symptoms and clearly low levels, alongside or after a trial of lifestyle changes.⁵

Does testosterone treatment cause weight loss?

In randomized trials, testosterone treatment did not reduce body weight. It modestly reduced fat mass and increased muscle mass.⁶

How to track it

If you are working on your weight and also watching your hormone results, a steady record helps you and your doctor read the numbers.

Logging meals in TrueCal and weighing in regularly gives you that record.

• Log your food most days. Together with your weight trend, a consistent log shows whether you are eating below, at or above maintenance.
• Track your weight trend, not single weigh-ins. Daily weight moves with water and food, so the trend over weeks is the useful number.¹¹
• Note where you are when blood is drawn. Whether you were actively losing or had been steady for a while changes how a testosterone result should be read.⁹
• Bring the trend to your appointment. Weight change over the months between tests gives context a single lab value can't.

Common myths

• Myth, one low test means I have low T. Guidelines require repeat morning tests and symptoms, and up to 30 percent of low results are normal on retest.²⁹
• Myth, I can't lose weight until my testosterone is fixed. Obesity affects testosterone more than testosterone affects body fat, and testosterone treatment did not reduce body weight in trials.⁶
• Myth, fat turning testosterone into estrogen is the whole story. Lower SHBG explains most of the drop in moderate obesity, and the estrogen role is still unsettled.⁶
• Myth, diet gives the same rise as surgery. Average gains after bariatric surgery were about three times larger than after diet alone.⁸

A note on medical advice

This article is for general information and isn't medical advice. Talk with your clinician about your own situation.

Worked example

Take the 2024 averages. Total testosterone rose by about 7.2 nanomoles per liter after bariatric surgery and about 2.5 after a low-calorie diet. Dividing 7.2 by 2.5 gives about 2.9. In the other unit, about 210 nanograms per deciliter divided by about 70 gives 3. That is why the surgery gain is described as about three times larger than the diet gain.⁸

A closer look

Timing of the test matters. An expert review in the Journal of Clinical Endocrinology and Metabolism says testosterone should not be retested during the active phase of cutting calories, because levels may dip for a while and tend to improve for good once eating is more balanced and weight loss has leveled off.⁹

Questions and answers

Related guides

• TDEE calculator
• Weight loss plateaus and metabolic adaptation
• How big a calorie deficit is safe

Sources

1. Testosterone Deficiency Guideline. AUA. 2018.
2. J Clin Endocrinol Metab. Bhasin. 2018.
3. Eur J Endocrinol. Corona. 2013.
4. J Clin Endocrinol Metab. Grossmann. 2011.
5. J Clin Endocrinol Metab. Grossmann. 2017.
6. Clin Endocrinol (Oxf). Grossmann. 2018.
7. J Clin Endocrinol Metab. Grossmann. 2021.
8. Andrology. Ken-Dror. 2024.
9. J Clin Endocrinol Metab. Muir. 2025.
10. J Urol. Mulhall. 2018.
11. Physiological Reports. Bhutani. 2017.