Naa, I think I have the LRC record. Not that I'm "happy" that I was in that bad of shape.
I lost 110 pounds in one year, April 2008 to April 2009 (My birthday to be specific). I started at 284 pounds and was 174 a year later. (Male, age 34 to 35, height 5'11").
So yea, 50 in half the time should be "easy." In fact I was probably down about 60 in the first half of my year journey. I hit a plateau for about 6 weeks around Thanksgiving of 2008.