I'm keeping this post short because I'd like you to actually go and read this article. The entire site is great, and while you can see at a glance that it is well researched and much-awarded, if you engage your critical thinking skills you will appreciate their links and research even more.
Basically, all of the common place accusations made by knowledgeable medical staff on the adverse and even deadly consequences of obesity are all based on a couple of studies with deeply, flagrantly flawed methodologies, sample groups, and statistical analysis. Really. All the media heads constantly harping on how being fat is a killer character flaw, all the oh-so-trendy legal initiatives aimed at ameliorating America's obesity epidemic, all the billions of dollars spent on diet products is all based on quack science.
I know what you're thinking, I didn't believe it at first either. It flies in the face of everything we think we know about health. But do like I did - go, and read, and think critically. I bet you'll be surprised.
Many thanks to Fat Jamin and Fat Kira for pointing this site out to me years ago :-)