When I went to university just after high school, I met a very nice young woman who had a very rounded abdomen that looked like a near-term pregnancy. I lost touch for a while, but a couple years later, I saw her, and her belly was nearly flat. Still young, and not yet introduced to FA, I asked her about her weight loss. She told me that a volleyball-sized ovarian cyst had been removed from her body.
I was absolutely stunned. It was the first I'd heard of such a thing, and it horrified me to know that her cyst had gone undetected for so long--that she had spent so much time and effort trying to lose weight, when it wasn't weight that could be lost without surgical intervention.
Of course, not to be spared any of life's most wonderful experiences, four years ago, my own body decided to produce several cysts, one of them quite large, necessitating the removal of an entire ovary, the fallopian tube next to it, and a chunk of uterus, all of which had been engulfed in the cysts and could not be salvaged. It was an emergency surgery, due to the cysts being previously undiagnosed, and growing to a point where they suddenly caused acute, unceasing abdominal pain that landed me in the ER.
Ovarian cysts often go undetected because the women who have them are blown off as lazy overeaters. Instructed by doctors to "diet and exercise", patients can become frustrated and stop bothering to get medical care. The cysts continue to inflate--they fill with fluid, and can reach some mind-boggling proportions. A Texas woman had a 156-lb cyst removed in 1994. That pales in comparison to the world record, a 328-lb cyst removed from yet another Texas woman (what's in the water there?!) in the early 1900s, but a 156-lb cyst, as well as a 93-pounder and 66-pounder, are still problematic.
A woman carrying around a large ovarian cyst may experience disabling pain, and she may have her activity levels severely curtailed. With a reduction in activity, her metabolism may slow down, causing her to gain weight on top of having the weight of the cyst. By the time she finds a doctor willing to treat her actual problem (instead of berating her for being fat), she may have developed additional health problems related to being sedentary.
No amount of diet and exercise is going to make the cyst disappear. The rest of the body may lose mass, but the cyst will not shrink. There are generally only a couple of options for treatment; one is surgical removal of the cysts, and the other is hormone treatment in the form of birth control pills. Generally, most cysts will go away on their own once a woman starts taking birth control pills. Of course, weight gain is also a symptom of taking oral contraceptives; it would be great if fatophobes would understand that sometimes gaining weight on a medication is better than not having the therapeutic effects of the medication.
So the next time you see a woman that you think is OMGFAT, and you think it's somehow your business to get upset about that, consider the fact that the above is just one of many medical conditions that can make a person appear to be fat, and it is often one that goes untreated far too long because too much attention is paid to making people thin instead of making them healthy. You might also consider that she is on a medication that is keeping her healthy, and being fat is a side effect of that medication. Asking a woman about the status of her reproductive system, though a favorite hobby of aunts and mothers-in-law, is generally considered to be a gauche thing to do, so the best thing to do is assume that her health and reproductive system are private matters between her, her physician, and possibly her significant other, no matter how badly your screwed-up, bigoted aesthetic sense is upset by the sight of her.