In the summer, the season of exposure, if you can't lose weight no matter how hard you try, you should visit a doctor if you have a form of obesity that concentrates fat on your face, neck, chest, or stomach. This is because there is a high possibility that you have Cushing's syndrome, a rare disease that causes hormonal abnormalities.

Dr. Jang Han-na, a professor in the Department of Endocrinology and Metabolism at Kangbuk Samsung Hospital, explained on the hospital’s YouTube channel that, in the case of general obesity, fat accumulates in the body as a whole, causing weight gain in most areas, including the arms and legs. 

In Cushing's syndrome, the distribution of fat is mainly concentrated around the face, neck, chest, and stomach, and the arms and legs become thinner, showing centralized obesity, she said.

"If you have symptoms of weight gain in only certain areas, unlike general obesity, it is necessary to consider obesity caused by Cushing's syndrome and visit a hospital."

Cushing's syndrome occurs when the body is exposed to higher than necessary amounts of glucocorticoids, a type of steroid hormone, for a prolonged period. 

The most common cause is iatrogenic Cushing's syndrome, which occurs when large amounts of steroids are introduced into the body externally to treat other conditions.

There is also endogenous Cushing's disease, in which a tumor in the pituitary gland causes the adrenal glands to overproduce adrenocorticotropic hormone, regulating cortisol secretion, and adrenal Cushing's syndrome, in which a tumor in the adrenal glands causes them to overproduce cortisol.

"There are patients who come to the hospital suspecting obesity caused by Cushing's syndrome because they can't lose weight no matter how much they diet," Dr. Jang said.

The most common symptom of Cushing's syndrome is weight gain. "The weight gain is mainly in the center of the body, such as the face, neck, chest, and stomach area, while the arms and legs become thinner," said Dr. Jang. "Fat accumulation on the face causes the face to be rounded like a moon, and there is excessive fat accumulation on the back of the neck and shoulders."

In Cushing's syndrome, there is also increased body hair on the face and body, and reddish-purple striae appear on the stomach, thighs, and arms. There are other characteristic symptoms as well.

"Facial flushing, thinning of the skin, and easy bruising," explains Dr. Jang. "The loss of protein in the body can also lead to muscle weakness, osteoporosis, and fractures," says Dr. Jang. "It can also cause high blood pressure, diabetes, recurrent infections, and sexual dysfunction."

Cushing's syndrome doesn't just cause a host of illnesses. If left untreated, complications such as cardiovascular disease and infections can lead to a 50 percent mortality rate within five years, making early detection and treatment crucial. 

The treatment depends on the cause of Cushing's syndrome.

"Iatrogenic Cushing's syndrome caused by an overdose of steroid medications can be treated by gradually stopping the medication," explains Dr. Jang. "However, abrupt discontinuation of the medication may cause hypoadrenocorticism, so caution is required."

The primary treatment for Cushing's disease caused by a pituitary tumor is surgical removal of the pituitary tumor.

"If surgery fails to completely remove the tumor or if it recurs, reoperation, radiotherapy, or medication may be considered," says Dr. Jang. "For adrenal Cushing's syndrome, it is treated by surgically removing the adrenal tumor. Surgical treatment is more effective than radiation or medication. Surgery is the first-line treatment for Cushing's syndrome unless there is a specific case where radiation or medication is not an option due to its many side effects."

Surgery as a treatment for Cushing's syndrome requires a period of time taking steroids, which ironically are the cause of the disease.

"After pituitary tumor removal, the remaining pituitary gland is less able to produce adrenocorticotropic hormone, which stimulates the adrenal glands to secrete cortisol. Additionally, during surgery for Cushing's syndrome, one adrenal gland, which is the cause of Cushing's syndrome, is removed, and the remaining adrenal gland that remains after removal is atrophied due to chronic over-secretion of cortisol and does not produce cortisol well."

"Steroid supplementation is necessary until the suppressed pituitary and adrenal gland functions are restored after surgery for Cushing's syndrome," said Dr. Jang.

After surgery, the dose of steroids is gradually reduced to match the body's ability to produce cortisol.

"Over time, once the pituitary gland and adrenal glands have recovered and the body is able to secrete cortisol normally, steroids can be discontinued," says Dr. Jang. "This process usually takes more than six months, so it is necessary to take steroids for at least six months after surgery for Cushing's syndrome."

In addition, even if Cushing's syndrome is well-treated with surgery, patients need long-term follow-up in the hospital.

"Obesity, myopathy, osteoporosis, hypertension, diabetes, sexual dysfunction, etc., which occur in Cushing's syndrome, do not improve immediately after surgery, so it is necessary to visit the hospital regularly even after surgery," Dr. Jang emphasized.