Which areas of the face respond well to fat loss via diet and exercise?

You ask a very good question!  The bottom line is that weight loss has different effects on the fat distribution on everyone.  The area you show typically does not change much after buccal fat reduction. In your case, you may want to consider liposuction of the jaw line/neck.  I'd recommend an in person examination to get a better idea of what options are available to you.  It is important that you seek the advice of a surgeon who is certified by the American Board of Plastic Surgery and who has extensive experience with buccal fat reduction surgery.  
I wish you the best! 
Dr. Gabbay.

It's hard to predict how the face will thin with diet and exercise. This area may be improved with a combination of facial liposuction and/or buccal fat removal.  Please visit a board-certified facial plastic surgeon for a consultation to see what options would be best for you and to formulate a treatment plan. I hope this helps.

Thanks for your question

The buccal fat pad is a rounded mass of fat in the middle of your cheek. It’s located between facial muscles, in the hollow area beneath your cheekbone.
The size of your buccal fat pads affects your face shape. Everyone has buccal fat pads. However, the size of buccal fat pads can vary greatly. If you have larger buccal fat pads, you might feel like your face is too round or full. You can be a candidate for a Buccal Pad removal surgery.

Best of Luck