Can Testosterone Therapy Help with Weight Loss in Men?

Testosterone deficiency (hypogonadism) is common in older men and men with obesity. Weight gain and obesity affect testosterone levels, and testosterone levels affect weight gain and obesity. This is often seen as a “vicious cycle,” and low testosterone may contribute to weight gain by:

• Reducing lean (fat-free) mass. Less lean mass can slow metabolism.
• Increasing belly fat. Hormonal imbalances can cause fat to distribute around the abdomen.
• Lowering energy levels. This can make physical activity feel more difficult.
• Changing insulin sensitivity and increasing hunger hormones. This may lead to insulin-related fat storage and excess hunger.

Weight gain may contribute to testosterone deficiency by:

• Lowering sex hormone-binding globulin (SHBG), which carries testosterone through the bloodstream. Lower SHBG means lower amounts of testosterone in the bloodstream.
• Suppressing the brain pathway that controls testosterone production.
• Converting testosterone to estradiol through the aromatase enzyme. Aromatase lives in fat cells, so increased fat cells can lead to low testosterone and higher estrogen levels.

Weight loss may help testosterone regulation in men. However, losing weight through diet and exercise may also reduce lean mass. While fat is most of the weight lost, at least a quarter of the weight loss may be lean mass. Not to worry, some loss of lean mass is expected during weight loss. Regular protein intake and resistance exercise can help preserve muscle. This would lead to more fat loss than lean mass loss.

TRT Helps Maintain Weight Loss and Lean Mass

Testosterone replacement therapy (TRT) is typically prescribed to testosterone-deficient men. TRT can bring men's testosterone levels closer to normal and help with symptoms. For testosterone-deficient men who are also trying to lose weight, TRT could complement lifestyle changes such as diet and exercise.

Some studies have found that TRT may support weight loss efforts. With diet changes, men may lose weight and reduce their BMI and abdominal circumference. However, weight loss may also include the loss of lean mass. After returning to their regular diet, men not on TRT may lose lean mass, while men on TRT may continue to lose weight and regain lean mass.

Patients Taking GLP-1s May Benefit from Concurrent TRT

Men with obesity may also have testosterone deficiency. Depending on other factors, some may be candidates for both glucagon-like peptide-1 (GLP-1) receptor agonists and TRT. GLP-1s can cause rapid weight loss by:

• Suppressing the “food noise” that hunger hormones contribute to.
• Slowing digestion so the stomach feels fuller for longer.
• Controlling insulin release to reduce spikes and crashes.

Because of how rapidly weight can be lost on GLP-1s, men may lose a large portion of lean mass as well. Lean mass is important because it helps burn calories (metabolism) and maintain bone and joint strength. Through these results, heart health, physical function, and overall quality of life may also improve.

While taking GLP-1s, it is important to keep up with strength training and protein intake. Regardless of testosterone levels, this practice can help preserve muscle with drastic weight loss. For men with testosterone deficiency, adding TRT may help maintain lean mass and manage metabolic issues. However, there is not enough research on the subject to confirm that this is true.

Key Takeaways

• TRT is not a weight loss method. Men who are both testosterone-deficient and obese may benefit from TRT alongside traditional weight-loss efforts.
• Testosterone and obesity have a “vicious cycle” relationship. Low testosterone may contribute to weight gain, and obesity may contribute to low testosterone.
• TRT combined with weight-loss efforts may help maintain lean mass. This could improve quality of life and some physical symptoms of testosterone deficiency.
• If weight gain or low testosterone is affecting your quality of life, it may help to speak with a sexual healthcare provider.

Resources

Canal de Velasco, L., González Flores, J. E., Kraus Fischer, G., Morales Arteaga, J. L., Olivares Casas, M., Álvarez Nava, K. N., & Morales Morales, F. M. (2026). Testosterone replacement therapy as a potential strategy to preserve lean mass in men with persistently low serum testosterone receiving GLP-1 receptor agonists: A narrative review. Cureus, 18(3). https://doi.org/10.7759/cureus.105734

Ng Tang Fui, M., Prendergast, L. A., Dupuis, P., Raval, M., Strauss, B. J., Zajac, J. D., & Grossmann, M. (2016). Effects of testosterone treatment on body fat and lean mass in obese men on a hypocaloric diet: A randomised controlled trial. BMC Medicine, 14(1). https://doi.org/10.1186/s12916-016-0700-9