I'll tell you the truth: yes, you could certainly lose the weight without surgery.
For many of us, losing it wasn't the problem. In fact, I've revealed previously that I've lost 200+ pounds over the years prior to resorting to bariatric surgery. Yep...I'd lose 30, regain 50, lose 50, regain 60, lose 60, regain 100, then rinse and repeat the miserable yo-yo process.
Keeping the weight off is the problematic issue here.
Personally, bariatric surgery has been my last hope for keeping the weight off. So far, since entering maintenance a year ago, my weight has been the most stable it's been in my entire adult life.
A clever physician who specializes in obesity medicine stated, "If you disliked what you did to lose the weight, you'll dislike what you've gotta do to maintain the weight. Therefore, you'll regain the weight."
The pre-op diet is good for short-term weight loss, but it ain't sustainable in the long run. If we are true to ourselves, we'd know deep down that we really wouldn't adhere to two shakes a day and a 'sensible' protein dinner for the rest of our lives.
Good luck to you.