How Gynecomastia Affects Men’s Chest Shape, looking like female breasts

Updated on Aug 19, 2026

Gynecomastia, enlargement of male breast tissue, informally called "man boobs", is a common medical condition. It affects up to 70% of adolescents boys during puberty, up to 70% of men aged 50 to 69, and 35 -40% of healthy men over their lifetime. It is caused primarily by a hormonal imbalance between testosterone and estrogen, and is classified using the Simon system into four grades (I–IV) based on severity, ranging from mild enlargement around the areola to significant, drooping, feminine-looking breast tissue. Gynecomastia is not just an aesthetic issue, and can cause significant emotional distress.

Key Takeaways

• Gynecomastia is a common condition affecting 60–70% of men at some point in their lives, resulting from a hormonal imbalance between testosterone and estrogen.
• It can occur in men of any fitness level, including bodybuilders using anabolic steroids.
• The condition is classified into four grades based on severity, from mild enlargement around the areola (Grade I) to severe enlargement with drooping nipples (Grade IV).
• Various factors contribute to gynecomastia, including certain medications, excessive alcohol use, aging, and underlying health conditions.
• It can lead to significant psychological distress, affecting self-esteem and social situations, highlighting the importance of addressing both the physical and emotional aspects of the condition.

Gynecomastia: The "Man Boobs" Condition

Gynecomastia is a common breast disorder in men, characterised by enlargement of male breast tissue. It affects an estimated up to 70% of adolescent boys during puberty and up to 70% of men aged 50 to 69, with an overall lifetime prevalence of 35–40% in healthy men. It causes physical discomfort including breast tenderness, swelling, and changes to chest shape and appearance.

Notably, gynecomastia can affect men regardless of overall fitness. Bodybuilders who abuse anabolic steroids can develop the condition, even with well-defined deltoids, biceps, triceps, and abdominal muscles, gynecomastia can give the chest a feminine-looking appearance.

This is part of why the condition has earned the nickname "man boobs."

Why and How Men Get Gynecomastia

Hormonal Imbalance

Gynecomastia is most commonly caused by an imbalance between testosterone and estrogen, the two hormones present in the male body.

Testosterone's key functions:

• Sexual development
• Sperm production
• Sex drive
• Muscle growth
• Red blood cell production
• Mood regulation

Estrogen's key functions in men: regulates bone density, cholesterol metabolism, and cognitive function.

When these hormones become imbalanced, effects can include sexual dysfunction, infertility, fatigue, muscle and bone loss, mood changes, sleep disturbances, increased body fat, and gynecomastia.

Gynecomastia typically develops when testosterone is low relative to estrogen. In some cases, however, higher-than-normal testosterone triggers aromatisation, a process where excess testosterone converts into estrogen, stimulating breast tissue growth.

Other Contributing Factors

• Anabolic steroid use
• Ageing
• Secondary hormonal causes
• Tumours (testicular, pituitary)
• Liver problems

Medications

Certain medications have been reported as possible causes of gynecomastia ^[1], including:

• Ketoconazole (antibiotic)
• Cimetidine, ranitidine, omeprazole (antiulcer medications)
• Growth hormones

Alcohol Intake

Excessive alcohol consumption can lead to alcoholism, which may cause liver cirrhosis, a known contributor to gynecomastia ^[2].

Underlying Health Conditions

In adult males, gynecomastia is commonly linked to another underlying condition ^[3], such as:

• Liver or lung cancer
• Cirrhosis of the liver
• Overactive thyroid
• Hormone-related conditions (cancer of the pituitary gland, adrenal glands, or testicles)

The Four Grades of Gynecomastia

Gynecomastia severity is classified into four grades ^[4], a system first identified by Simon et al. in 1973:

Gynecomastia Grade I

Gynecomastia Grade II

Gynecomastia Grade III

Gynecomastia Grade IV

More Than a Physical Issue: The Emotional Impact

Gynecomastia often causes significant emotional distress and embarrassment, particularly in situations requiring shirtlessness, at the beach, by the pool, or in changing rooms.

"Patients who consult me for gynecomastia generally are very distressed, and they have low self-esteem due to their 'feminine-looking breasts.' They often have difficulty finding clothes that fit and are wary of wearing light-coloured or fitted T-shirts.", Dr Ivan Puah, an MOH-accredited liposuction doctor specialising in male chest contouring and gynecomastia surgery and lead author of a study on Surgical Management of Gynecomastia in Asian Men.

Gynecomastia is a medical issue, not purely an aesthetic one, its impact extends across mental, physical, and emotional wellbeing.

FAQ

What percentage of men are affected by gynecomastia?

Gynecomastia affects up to 70% of adolescent boys during puberty, up to 70% of men aged 50 to 69, and 35–40% of healthy men over their lifetime.

Can bodybuilders get gynecomastia?

Yes. Bodybuilders who abuse anabolic steroids can develop gynecomastia even with an otherwise muscular, well-defined physique, since steroid use disrupts the testosterone-to-estrogen balance.

What causes gynecomastia?

Gynecomastia is primarily caused by a hormonal imbalance between testosterone and estrogen. Contributing factors include anabolic steroid use, ageing, certain medications (like ketoconazole or antiulcer drugs), excessive alcohol intake, and underlying health conditions such as liver disease, thyroid disorders, or tumours.

How is gynecomastia severity graded?

Gynecomastia is classified into four grades, from Grade I (mild enlargement around the areola) to Grade IV (severe enlargement with a distinctly feminine, drooping chest appearance).

Is gynecomastia just a cosmetic issue?

No. Gynecomastia is a medical condition that can cause physical discomfort, signal underlying health issues, and lead to significant emotional distress and low self-esteem.

Can medications cause gynecomastia?

Yes. Medications including ketoconazole, cimetidine, ranitidine, omeprazole, and growth hormones have been reported as possible causes.

Does alcohol consumption cause gynecomastia?

Excessive alcohol intake can lead to liver cirrhosis, which is a recognised contributor to gynecomastia.

Reference

1. Goldman RD. Drug-induced gynecomastia in children and adolescents. Can Fam Physician. 2010;56(4):344-345. PMID: 20393092; PMCID: PMC2860825.
2. MedicineNet. Male breast enlargement and alcohol. Available at: medicinenet.com.
3. Stanford Health Care. Gynecomastia: causes. Available at: stanfordhealthcare.org.
4. Simon BE, Hoffman S, Kahn S. Classification and surgical correction of gynecomastia. Plast Reconstr Surg. 1973;51(1):48-52.