As you can see by my sig I've lost quite a bit, but not very rapidly. I am over that age that comes after 39, on medication so all of those things slow down your losses.
One thing about losing slowly is your skin also has a better chance of snapping back, so to speak. Of course, genetics, age and other factors play a role in this as well.
Since this is a change for the rest of your life, I really recommend you not be in a specific hurry to lose X amount of weight in X amount of time. I mean, in 8 months it's not like you aren't going to be around anymore.
50 pounds in 6 months can be a very fast rate, deepending upon your size. If you have a lot of weight to lose it IS possible, but if you only have 50.. in my opinion its not likely to happen. I am sure there have been exceptions, but this is just my opinion based upon what I have observed in the real world. So what if you only lose 25 pounds in six months? That won't make you a failure AND you'll be 25 pounds thinner.
This way of eating is about more than just weight loss. This way of eating is about improving your health, first and foremost. Weight loss is a nice side effect.
I cannot stress enough the importance of exercise because your first goal is to be healthy and we ALL need exercise for our health. Even if I never lose another pound, I will keep exercising because that is what we must do to be healthy. I don't particularly like going to the GYN every year, getting mammograms, flossing.. etc. but these are all things we do for health. Exercise is a non negotiable part of my day.. period.
What ever plan you chose, it's the same rule.. calories in calories out. Good Luck with whatever you choose.