I agree it is a good thing to lose weight but I don't put too much hope it will lower my pressure. My Dr. told me 'you have the throat of somebody with sleep apnea'. So, I know that's one of the reason I have sleep apnea.
Second, I see my AHI goes higher (the pressure needed too) if I stop using the cortisone spray for my sinuses for several days. My allergic rhinitis starts showing up.
Third, if I eat before going to bed or if I eat for dinner food I know difficult to digest guess what? the AHI goes high so the pressure too. Why? Because I make acid reflux, the throat closes to protect from the acid going into the lungs. This is perceived as an apnea, the pressure goes up etc etc, all this was explained to me by my Dr. I tested it and I can say he is right. If I check what I eat and when my AHI is lower.
Fourth: somebody here at the forum made a comment and add a link about an American hospital where a study was made with obese people whom had gastric surgeries to reduce weight. They said those people after having lost the weight still needed their CPAPs.
Conclusion: losing weight doesn't guarantee anything about OSA.
Something I have noticed after 2 years on APAP and one year walking more than 3km around 4 to 5 times a week is that my high blood pressure problem is improving. My medication has been cut at half. I have heard that losing weight aids with high blood pressure.,
Once I lost a lot of weight and the blood pressure stayed high but in that time I'm sure I had already OSA and was not treated that's maybe the reason why I had no improvement. I will let you know what happens.