Typically, an imbalance of the feminine hormone oestrogen and the male hormone testosterone results in breast growth among men. Both sorts of hormones are present in males' bodies. Males may develop larger breasts as a result of changes in the body's use or sensitivity to these hormones, as well as changes in their levels. Gynecomastia develops when oestrogen hormone levels rise and testosterone hormone levels fall for some reason.

Being obese or having excessive body weight is another common cause of gynecomastia. Extra weight can lead to increased levels of oestrogen in the male body and can cause breast tissue to grow. Also, overweight men are more likely to have extra fat, enlarging the breast tissue.

Sometimes newborn baby boys have enlarged breasts to a certain extent. Breast development in neonates is caused by exposure to the mother's oestrogen. Breast buds, which are enlarged breasts at birth, are present in about 50% of newborn boys. They can stay longer, but usually, disappear in two to six months.

At puberty, boys’ hormone levels vary and in case of a drop in testosterone, oestrogen can lead to the growth of breast tissue. This is why many teenage boys may have breast enlargement to some degree. Teenage gynecomastia wears off when one starts growing and the hormone levels stabilise.

When growing older, men start producing less testosterone and gain more body fat, resulting in enhanced production of oestrogen, thereby, gynecomastia.

• Hormonal imbalance from falling levels of testosterone and rising oestrogen levels

• Extra weight can lead to increased levels of oestrogen and cause breast tissue to grow

• Exposure to the mother's oestrogen can cause breast development in newborns

• Irregular variation in hormonal levels during puberty

• Decreased production of testosterone with growing age

• Side-effects of certain drugs