Best Approach to Loose Skin and Fat on Upper Arms?

Based on the information you've provided and your photo, you'll probably need an arm lift rather than liposuction. This is because if you remove a lot of fat in your upper arms with liposuction alone, you'll have loose skin that may not be able to retract to your leaner contour. This loose skin will make the results of your liposuction hard to see. An arm lift will remove the excess fat and skin to give you a better result.  

Congratulations on such a great weight reduction. You probably will not get enough benefit from lipoosuction alone, whether laser-assited liposuction or tumescent lipoosuction followed by Thermage external radiofrequency tightening After these procedures, your skin will not retract enough and you will end up seeking a plastic surgeon to do an arm lift, so I would suggest you see a board-certified plastic surgeon to discuss the type of scarring that is expected with the arm lift and other risks and consequences.
 

Judging by your photos I would recommend an arm lift.  Liposuction will produce a slight improvement but you already have laxity in the skin and excessive skin as well.  So liposuction will not address the loose skin that you have and will need the skin resected.  In some patients there is some benefit to staged surgery with liposuction and then a brachioplasty at the second stage.  It really depends what the patient expectations are.

But with brachioplasty alone, the excess skin will be removed while with liposuction if will only get more loose.

Based on the photograph that you posted, its difficult to assess how heavy your arms are. For patients with heavy arm tissues and loose skin, I recommend a staged arm liposuction followed by arm lift 2-3 months later. The scars appear to be better in this sequence.

Your photo shows both excess of fat and skin of the upper arm that will not be resolved satisfactorily with liposuction alone.  I recommend a combination of liposuction and surgical skin reduction that can be safely done in one setting.  Your elasticity at your current age may not be adequate to tuck the incisions into the axilla alone, you should consider a longitudinal ellipse to be excised that would carefully place the closure on the inside surface of the arm.