Updated: Apr 27
Let’s discuss some commonly asked questions about Testosterone and Weight Loss.
· Testosterone use for weight loss, does it work?
· Can Testosterone help me lose weight?
· Can TRT motivate me to lose weight?
· Can TRT improve and treat obesity?
· Is Low-T associated with obesity and being overweight?
(TRT) Testosterone Replacement Therapy
· Long term testosterone therapy in men with testosterone deficiency improves body composition and quality of life
· Long term testosterone therapy in obese men with testosterone deficiency improves all metabolic syndrome components.
· Long term testosterone therapy in men with testosterone deficiency, with or without lifestyle modification may prove effective in the treatment of obesity. (1)
Testosterone is very important metabolic and androgenic hormone. Testosterone regulates carbohydrates, lipids and protein metabolism, muscle mass, adipose tissue, inflammation, insulin sensitivity and body composition. Low testosterone (Low-T) levels, contributes to a decrease in muscle size, weight gain, increased fat mass, insulin resistance and metabolic syndrome. It is a well-known fact that obese and overweight men have lower testosterone levels compared to lean men. Men who utilize TRT can improve weight loss, waist circumference and muscle size.
In some clinical studies testosterone replacement therapy (TRT) can increase lean muscle size and mass and decrease fast mass in as little as 3 months.
A number of well published interventional studies have confirmed that when testosterone is given to obese men, testosterone can ameliorate metabolic syndrome components, reduce waist circumference, improve quality of life, and improve body composition. Some studies have suggested that testosterone therapy be considered an adjunct to the treatment of obese men.
The potential mechanisms relating Low-T to weight gain include increased levels of sex hormone binding globulin (SHBG), low levels of luteinizing hormone (LH), adipocyte (fat cell) dysfunction, androgen resistance, and insulin resistance.
Sex Hormone Binding Globulin (SHBG)
Also known as testosterone-binding globulin, sex-steroid binding protein (SBP), testosterone-oestradiol- binding globulin (TeBG)
The action of testosterone depends upon bioavailable testosterone in the body. Bioavailable testosterone is also known as free testosterone. A man’s total testosterone is combination of free testosterone and testosterone bound to proteins. One of these proteins that bind reversibility with high affinity and inactivates testosterone is SHBG. Approximately 60-80% of testosterone in the body is bound to SHGB, 20-40% bound to albumin and only 2-3% is free and active. SHBG levels are increased in conditions where estrogen levels increase such as liver disease (cirrhosis), hyperthyroidism, prolonged calorie restriction, and medications. Low-T promotes elevated levels of SHBG and contributes to low testosterone levels and weight gain.
Luteinizing Hormone (LH)
LH is a signaling hormone released by the pituitary gland. When LH is released into the body, it travels to the testicles and binds to a receptor on the Leydig Cells. The Leydig Cells are located in the testicles and synthesize testosterone. More specially Leydig Cells convert cholesterol to testosterone. Men who are overweight or obese have a low levels of LH secretion and therefore less testosterone synthesis.
In prospective study Saad F et. al 423 men with Low-T were given injections of testosterone undecanoate in 12-week intervals for up to 10 years. Body weight decreased from 97.3 to 84.6 kg. Waist circumference decreased from 107 to 92cm and BMI decreased 31 to 27kg/m2.. Results supported that TRT increased lean body mass and decrease fast mass. Testosterone acts directly on adipose tissue, decreasing fat mass and reducing visceral (around the abdomen) fat.
Fat acts differently to testosterone therapy depending on its location in the body. The effect of testosterone on fat distribution is becoming more well known. Adipocytes (fat cells) differ in their histological and biochemical characteristics depending on their location in the body. For instance, abdominal fat is made up mostly of large adipocytes that aromatize testosterone to estrogen more than other fat cells. Lipoprotein lipase an enzyme found in fat cells that breaks down triglycerides to energy for the body to utilize has higher activity in fat cells predominately located in femoral fat (thighs and legs). As a general rule, adipose tissue anywhere in the body, will in some degree metabolize testosterone. There is a direct correlation between body weight and the clearance rate of androgens. Clinical studies have found that men and women with higher body weight and obesity have higher metabolic clearance rates of testosterone than age-matched controls with normal body weight. Obesity increases the breakdown of testosterone and increases estrogen in the body that can lead to further insulin resistance and further weight gain.
The mechanism by which testosterone reduces fat cell loss is hypothesized to be from inhibiting adipogenesis (the formation of new adipocytes/fat cells) and up regulating myogenesis (muscle building). Testosterone is believed to cause nitrogen retention which may signal protein synthesis, promoting muscle and lean mass growth. An Increase in lean muscle mass will increase metabolism propagating the fat cell loss cycle.
For men with Low-T desiring to lose weight and reduced waist circumference testosterone supplementation is a viable alternative when combined with an exercise routine and a healthy diet. Testosterone therapy can be a great motivator as well to weight loss. TRT has been shown in clinical studies in men with Low-T to improve mood, reduce fatigue, enhance energy thereby motivating a man be more active.
1) Traish et. al, Testosterone and Weight Loss: The evidence. Curr Opin Endrocinol Diabets Obes. 2014 Oct; 21(5) 313-322, 2014 Aug 28.