Does HIFU dissolve fat?

Hi,
Yes it does. Therefore if you have an aging face where the subQ fat is getting thinner, a procedure which reduces this fat will make you look older.
Ali Rıza Öreroğlu, MD, FEBOPRASDouble Board Certified Plastic Reconstructive and Aesthetic SurgeonIstanbul - TURKEY

High-intensity focused ultrasound (HIFU) is a fat loss procedure that noninvasively reduces fat in the targeted area. The goal of the procedure is to reduce fat using thermal energy delivered via ultrasound. If you are worried about losing fat in your face, then HIFU may not be the right procedure for you.The effects of HIFU treatments are localized to the targeted area, so you may still be a goodcandidate for the procedure in other areas where you would like to lose fat. If you areinterested in noninvasive methods to tighten your facial skin, then schedule an appointmentwith a board-certified doctor in your area to learn more about the options available to you.Hope this helps!

Far more important than the technique is the skill and experience of your plastic surgeon. Choose your surgeon rather than the technique and let them explain why one technique may be better than another.  See the below link on some suggestions on finding the most qualified Plastic Surgeon for you.  Always insist on a board certified plastic surgeon.

Yes unfortunately this will reduce that in your face. He can make areas more sunken which are very difficult to repair and usually make a person look older. It’s best to stay away from that modality.