Endometriosis, a condition in which the tissues that normally line your uterus also grow in other parts of the reproductive system, is one of the most common gynecological diseases — and almost 11 percent of women suffer from undiagnosed endometriosis. 
Could your unexplained weight gain be caused by endometriosis?
A Quick Look At Endometriosis
Endometriosis and infertility often go hand in hand, as 30 to 50 percent of women are unable to conceive naturally, but physical pain is often the most debilitating feature of this disease. Pain levels change with your menstrual cycle, which tends to be highly irregular, and sex can also be painful. [2, 3]
The pain endometriosis causes can impact your professional life, social life, and relationships . Hence, endometriosis has a negative impact on most aspects of your life.
Different medical and surgical options are available for the treatment of endometriosis:
- Medications used to manage endometriosis include painkillers and hormonal therapies.
- Surgery for endometriosis includes conservative and non-conservative procedures. Conservative procedures are mostly performed laparoscopically and they aim to preserve fertility. Such methods are chosen for younger women and for the ones who have not completed their families yet. 
- Alternative treatment options for endometriosis involve the use of herbs and essential oils. Some pain relief methods, like acupuncture, are also adopted to make your quality of life better. 
What Causes Endometriosis?
The exact causes of endometriosis are still unclear. However, the disease occurs when the innermost lining of the womb, called the endometrium, grows outside the uterus. This tissue has the ability to grow and regress under the hormonal influence of estrogen and progesterone during the menstrual cycle .
Unlike the endometrial tissue present in your uterus, the ectopic endometrial tissues seen in women with endometriosis are not shed during your period. This is what leads to pain and cramping that is cyclic in nature.
Can Endometriosis Make You Gain Weight?
While there is no research to conclusively prove that endometriosis directly causes weight gain, women who suffer from this disease do, frequently, find themselves gaining weight. The causes of this weight gain are indirectly related to endometriosis.
What Causes Weight Gain In Endometriosis Suffering Women?
While endometriosis has not been proven to be a direct cause of weight gain, some women with endometriosis do experience abdominal bloating. This abdominal bloating occurs when endometrial tissues attach themselves to the gastrointestinal tract, and it can give the appearance of slight weight gain in some women. Hand swelling is also noticed in some patients, again giving the appearance of weight gain. 
Can The Treatment Of Endometriosis Cause Weight Gain?
It may not be endometriosis itself that has led you to gain a few extra pounds, but rather the treatment of it. Some medical and surgical treatment options for endometriosis are associated with weight gain.
How Do Hormonal Pills Cause Weight Gain?
Hormonal birth control pills have estrogen and progesterone in them. Out of these two hormones, estrogen can trigger you to gain weight.  The mechanism behind this weight gain is twofold — estrogen can lead you to retain fluid (edema) and also increases your appetite, which may lead you to eat more.
Does Hysterectomy Cause Weight Gain?
Hysterectomy is a surgical treatment option for endometriosis. It involves the removal of the womb and sometimes the ovaries as well. Those women who have completed their families or who don’t want to have children often choose this option, as do those whose endometriosis symptoms did not respond to other treatment options. If you are looking into how to get pregnant with endometriosis, hysterectomy is not an option for you, however.
After a hysterectomy, women often report weight gain. This occurs due to hormonal changes following hysterectomy. 
How Can You Avoid Weight Gain?
As you have seen, endometriosis can indirectly cause you to gain weight. In order to avoid weight gain after a hysterectomy, you should commit to lifestyle changes like a balanced diet and an active lifestyle. Alternative treatment options can be adopted to avoid weight gain associated with the use of contraceptive pills. These include alternative hormonal treatment like GnRH analogues or surgeries like laparoscopy. Talk to your doctor to decide on the best course of action for you.