Yes, hypo does mean 'under' - and when I searched out hypothyroidism, I came across myxedema. It seems to occur in very severe cases of hypothyroidism.

People with untreated hypo - or treated hyper - have weight gain as a side effect.

As her lawyer says:
Valdez has said Mayra Rosales, 27, suffers from myxedema, a thyroid disease that caused her to swell from about 220 pounds to her current bedridden state in only a few years.
I was trying to find out more about it...there is a tibular (sp?) and a pituitary kind...Google Images was a bit more helpful on this. I got the impression that the edema plus the slower metabolism work together to make the person HUGE. And - it's not always treatable.

RICHARD, maybe you would have the info I was looking for. Average weight gain of someone with this condition?