There are few side effects with fat transfer since your doctor will be injecting your own fat into the treatment area. Therefore, there is no chance for rejection or allergic reaction. The risks are very slight, but the biggest concern is the body reabsorbing the injected fat or the development of noticeable irregularities in the fat that is transferred. The longevity of the results sometimes can depend on your age and how rapidly you body metabolizes fat. Since you are a younger patient, the fat injections can last years with little touch up listed. For older patients, the results are more temporary as the body is absorbing a lot of fat at that age
Fat grafting is one option for a thinning face. You might want to consider reservable fillers initially to see if you like the results.
the trouble with fat grafting in young people is that the fat takes more efficiently and it may grow as you age.
it is not unusual for people to gain weight as they get older than 23 and the grafted fat grows with the weight gain. It rarely looks good, just blobby. It is also very difficult to remove. I have been doing fat for 25 or so years and you have to have the perspective of time to see these changes happen.
in my 23 year old face I would do HA fillers.
Fat grafts work very well in young patients. Our results are noticeably better in your age group then in older age (sixties) where this procedure is more frequently employed. In your age it is considered permanent; volume improvement 5-6 months after fat grafting is going to stay for years in patient of your age. In older group, due to continuous fat atrophy, duration of fat grafts is 2-4 years depending of the patient and area treated. Good luck.