Where Are The Low-Carb Studies?

Looking at the research, you can see a surge of low-carb studies that have been done over the past few years.  Still, I am wondering: where are the long-term studies that show low-carb is effective for weight loss?  Most of the studies I read show outcomes after 6 or 12 weeks.  Almost any diet can show weight loss in this short time span, before the rebound effect usually begins.

As far as I know, there are only two long-term low-carb weight loss studies (I'm defining long-term as 18 months or more).  Both show minimal weight loss for Atkins/low-carb.  You would think that since Atkins' diet book was originally published in the early 70s, thirty years would be enough time to produce some legitimate long-term studies.

All this isn't to say low-carb does or doesn't work for long-term weight loss.  Instead I'm just asking, where is the proof (beyond personal stories)?  People jumped on the low-fat bandwagon in the 80s because of short-term studies.  If low-carb is going to be more than this decade's bandwagon, there needs to be better studies done.