Unfortunately, the problem with losing weight or rather with gaining weight in the first place is sometimes the problems you suffer because of obesity don’t go away.  Generally speaking, when you lose weight, your cholesterol goes down, your blood pressure goes down, and moreover there have been many incidences of type 2 diabetes actually actively reversing itself, which obviously helps many to be motivated to actually get down and dirty and do the job, even if it takes surgery to properly discipline themselves and motivate themselves.  But unfortunately, sleep apnea, which is caused largely by obesity, is not one of these things. 

The most obvious thing would be that stretch marks and maybe loose skin would not necessarily go away just like that.  But sleep apnea is the same way.  It happens basically when you stop breathing in your sleep.  It may happen for just a few seconds, but in that few seconds, your brain is not actually getting the oxygen that it needs.  In some cases, unfortunately, they don’t start breathing again, and it’s scary every time it happens.  But either way, while you would expect most things to go away if they should choose to lose weight, that is one of those long term ones that you will suffer because you made that generalized mistake before.