Back Liposuction for Wedding Dress Fit

There is no way to definitiively answer that.
Liposuction can and will reduce the upper back fat. I have found that ultrasonic assisted lipoplasty is useful in removing fat in this area.
However, the behavior of the skin is unpredictable and this garment may still gather loose skin in the upper back creating a crease. Overall, I would expect that the garment would not feel as tight.
There is no doubt that other techniques such as microcannula, traditional, power assisted, or laser assisted liposuction technques can be used and will be recommeded by other practitioners.
Clearly, on your workout regime, I would advise you to avoid any excercises that would build up your latissimus dorsi ("lats") because this will only make your garment feel tighter. Many personal trainers advise this because they want to build up your muscle tone without regard for how you clothes fit.

Liposuction of the back can give excellent results, and I have seen people who needed to fit into their wedding dress do just that!

It’s not unusual for patients to be concerned about
fat collections in the area beneath the bra strap. Unfortunately, the fat in
this area is extremely fibrous and for this reason, liposuction of the upper
back is difficult and unpredictable. This problem is further complicated when
excess skin is present as well. Under these circumstances, improvement can be
anticipated, but the majority of patients aren’t totally happy with their
result.

In some cases, alternate strategies have been
utilized. Recently, coolsculpting has shown promise as a method that freezes
fat cells in the upper back area.

Most of these approaches result in improvement, but
don’t totally correct the problem. They’re associated with pain, discomfort,
inconvenience, and expense. Under these circumstances, it
might be appropriate to alter your dress rather than expose yourself to the
downsides of liposuction for what might be a limited benefit.

However, I don't think the fat on your back is an issue.  Based on the photo that you have shown it appears that it is the dress that should be altered.   You can easily have liposuction of your arms with great results but the upper back is more challenging and not necessary in your situation.

Hello dear!
Thanks for the pictures and provided information as well.
Based on your photos, you are a great candidate for liposuction in the troubled area, and I think you'll get very good results. 
In general, you need to be physically healthy and at a stable weight, have realistic expectations, be a non-smoker and your BMI needs to be 30 or less.
l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

Liposuction of the back bra roll and upper back is challenging, but possible.  The most challenging part is managing expectations.  While patients and surgeons both want the rolls in this area completely gone, this is typically not possible.  Generally, you can expect a 60% improvement in this area, but most likely you will still have some residual roll - especially if you have excess skin in this area.  Fat in this area is typically denser and more fibrous than fat in other areas and the back skin is firmly stuck to the tissues underneath.  The other tricky issue with liposuction of the upper back is scar placement.  I typically do not use incisions directly on the upper back because they would be visible when you wear backless tops, swimwear, etc.  Patients with heavy back bra rolls with redundant skin may require excision of these rolls - generally this puts a visible scar in the middle of the back near the bra line.  These are some of the options for you and your plastic surgeon to discuss.

Liposuction of the back works well. A non surgical alternative now offered is Coolsculping or fat freezing.  This is a non invasive, non surgical treatment option that works well for the upper back and bra line.  It is less expensive than liposuction and there is NO DOWN TIME!!!

I would have two primary concerns about liposuction in your upper back. First of all, liposuction results aren’t always predictable. With the fat in the area removed, you may still have some looseness in your skin following the procedure that ends up causing the same problem with the dress fitting as before the lipo.

Secondly, liposuction in this area can be very challenging from a technical standpoint. There are a lot of dense, fibrous muscles in the upper back and shoulder area that make removal of fat cells more difficult. That being said, I think a surgeon who is very skillful and experienced could make a difference.

Liposuction of the upper back region is more difficult and less reliable than liposuction of other areas such as the tummy. Most likely this is because the skin of the upper back is densly adherant to the underlying muscles. Laser liposuction can be done, but any liposuction procedure will have a better result after weight loss first.
The size of your chest, muscles and breasts are the main determinant of whether you can zip the dress in the photo and I do not think liposuction will make a difference in the ability to zip the dress. Weight loss will help and is the best option.