Gynecomastia, also known as "man boobs" or "moobs," is the over enlargement of the male breast in response to too much estrogen or too little testosterone.

According to Dr. Lulu Marquez on DZMM's "Private Nights with Dr. Lulu Marquez," men with gynecomastia have "big and rubbery" chests.

She also explained the causes of this breast enlargement in every age group.

For newborns: Gynecomastia is caused by estrogen from their mothers. Breast buds are common in baby boys, but it tends to go away gradually by 6 months.

For preteen boys: Gynecomastia can also be caused by an estrogen-producing tumor. Breast buds are common during puberty, and it may last up to 2 years. For some preteens, they tend to go away within the first year.

For teen boys: Gynecomastia is caused by the hormonal changes of puberty. It may occur in many boys during early puberty to middle puberty. Within 6 months to 2 years of puberty, breast buds usually go away.

For adult males: Gynecomastia is usually caused by another health condition, such as liver or lung cancer. Smoking cigarettes or drinking alcohol may also produce breast buds.

Marquez added that using of certain medications, such as steroids, medicines to treat ulcers and epilepsy, heart medicines, chemotherapy drugs, antiandrogen drugs, antianxiety and antidepressant medicines may also caused gynecomastia.

Gynecomastia can be diagnosed from a physical exam and medical history. If the breast lump is unusually large, a biopsy may be done.

Lack of exercise and being overweight may also result in excess body fat tissue being accumulated all over the body, including the area of the chest.

"Fats can produce estrogen which makes the breast buds or gynecomastia," she said.

Having a healthy lifestyle, proper diet and exercise may help prevent the development of gynecomastia.