Weight loss and testosterone

What the research found

In 2013, an Italian research group published a systematic review and meta-analysis in the European Journal of Endocrinology. They pooled 24 studies of men who lost weight through a low-calorie diet or bariatric surgery.

• Both approaches were associated with a statistically significant rise in total testosterone, and in free (unbound) testosterone.
• With diet, total testosterone rose by about 2.9 nmol/L on average, roughly 80 ng/dL.
• With bariatric surgery, which produces much larger weight loss, the rise was about 8.7 nmol/L, roughly 250 ng/dL.
• The rise was greater in men who lost more weight, and in younger men without diabetes who had greater obesity at the start.

Why it likely works

Body fat and testosterone influence each other. Excess fat, especially around the abdomen, is associated with lower testosterone, and low testosterone is associated with gaining fat. Losing fat appears to help break that cycle.

Limits to keep in mind

• Many included studies compared before and after without a control group, which makes the estimates less certain.
• It applies to men with obesity. It does not show that men at a healthy weight can raise testosterone by losing more.
• Bariatric surgery is a medical decision, not a lifestyle tip. It is included here because it shows the dose-response pattern.

What to do with this

• If you carry excess body fat, a sustained, moderate calorie deficit is the best-supported lifestyle step.
• Strength training and enough protein help preserve muscle while you lose fat. See exercise and testosterone for why training alone is not a testosterone fix.
• Talk to a doctor if you have obesity, diabetes, or other conditions before starting an aggressive diet.