Can gaining muscle mass help lower Sex Hormone-Binding Globulin (SHBG) levels and improve hormone balance?

Can Gaining Muscle Mass Lower SHBG and Improve Hormone Balance?

The claim that gaining muscle mass lowers SHBG is not supported by current medical evidence; in fact, resistance training and muscle gain typically increase SHBG levels, particularly in older adults, though this occurs alongside beneficial increases in testosterone and improved hormone ratios.

Understanding SHBG and Its Regulation

SHBG is produced in the liver and its synthesis is stimulated by estrogens 1. The relationship between muscle mass, exercise, and SHBG is more complex than the original claim suggests:

• In chronic liver disease, SHBG levels rise due to altered estrogen metabolism, though they ultimately decline with progression to decompensated cirrhosis 1
• In diabetes and obesity, SHBG levels are often low, which is associated with lower bioavailable testosterone 1
• Enzyme-inducing medications (like certain antiepileptic drugs) increase SHBG production, reducing biologically active sex hormone concentrations 1

Effects of Resistance Training on SHBG

Acute and Chronic Training Responses

Contrary to the claim that muscle gain lowers SHBG, research demonstrates:

• Resistance training increases SHBG levels in older adults (ages 60-75), alongside increases in testosterone, growth hormone, and DHEA 2, 3
• After 24 weeks of heavy resistance/power training, both older men and women showed increased SHBG concentrations 3
• A systematic review of exercise training in adults over 40 years found consistent increases in SHBG regardless of training mode, duration, or intensity (effect sizes: 0.19 to 3.37) 2

Hormonal Adaptations

The hormonal response to resistance training includes:

• No change in resting testosterone or SHBG after 12 weeks of high-volume resistance training in young men, though cortisol decreased by 17% 4
• Acute exercise-induced increases in growth hormone and cortisol during training sessions 4, 5
• Improved testosterone-to-cortisol ratios that correlate with strength gains, particularly in older women (r = 0.63) 3

The Real Mechanism: Improved Hormone Balance Despite Higher SHBG

The paradox is that while SHBG increases with resistance training, hormone balance actually improves through:

• Increased total testosterone production that outpaces the rise in SHBG, maintaining or improving free testosterone levels 2, 3
• Enhanced insulin sensitivity from increased muscle mass, which indirectly affects sex hormone metabolism 1
• Reduced visceral adiposity, which is associated with metabolic syndrome and hormonal dysfunction 1

Clinical Context: When SHBG Changes Matter

In Men with Diabetes and Hypogonadism

• Men with diabetes have lower testosterone levels and often decreased SHBG compared to age-matched controls, with obesity as a major confounder 1
• When total testosterone is near the lower limit, measuring SHBG is reasonable since it is often low in diabetes and associated with lower testosterone levels 1
• Resistance training improves muscle mass and strength, which are beneficial outcomes in symptomatic hypogonadism, independent of SHBG changes 1

In Athletes and Energy Deficiency

• Energy deficiency (not muscle mass per se) causes hormonal suppression including hypogonadism in both male and female athletes 1
• Adequate energy availability is critical for maintaining normal hormone function, with bioenergetic hormones (T3, IGF-1) showing significant declines with energy deficiency 1

Evidence-Based Recommendations

For improving hormone balance through muscle gain:

• Resistance training 2-3 times per week for at least 12-24 weeks increases muscle mass, strength, and favorable hormonal adaptations including testosterone, growth hormone, IGF-1, and DHEA 2, 3
• Adequate energy and protein intake (≥1.2 g/kg/h carbohydrate post-exercise, sufficient protein) is essential to support muscle protein synthesis and hormonal function 1, 6
• Weight management through resistance training reduces visceral fat and improves metabolic parameters more effectively than SHBG reduction alone 1

Critical Caveat

The original claim conflates SHBG reduction with improved hormone balance. Lower SHBG is not inherently beneficial—it is often a marker of metabolic dysfunction (obesity, insulin resistance, diabetes) 1. The goal should be optimizing the testosterone-to-SHBG ratio and overall anabolic-to-catabolic hormone balance, which resistance training achieves despite increasing SHBG 2, 3.