Mike,
I believe that general estimates claim that for every 30-35 lbs lost, a man can expect to see an additional inch added to length. This is because of the fat pad that is just above and surrounds the penis. I believe that this number is an average and may not hold true for everyone. Everyone has their fat distributed around their body differently. I can say that in one of my previous attempts at weight loss, I dropped 50 lbs and I noticed a very big difference. I totally understand your desire to know what might happen. I can tell you that this can be a really good motivationer. I am scheduled for sleeve surgery in September and I can tell you that this is one thing that I am definitely looking foward to.