What’s the best lip filler for natural results? Is micro fat transfer reliable?

I would highly recommend getting a formal evaluation with and treatment from a board-certified cosmetic dermatologist and expert in facial sculpting. Technique is the key to a successful lip augmentation with fillers, so you'll want to see someone meticulous. An experienced physician will be able to determine which filler, how much filler, and which technique will give you the subtle result you're looking for. See an expert. Best, Dr. Emer

Dear Michelle Vasquez,
I perform a lot of lip injections with fillers such as juvederm and it works great. Many times I need to put more in one side than the other to attempt to even out the vermillion border (The red line of the lip). This helps provide more symmetry at times.For patients looking for a more long lasting result, I recommend fat grafting. That is, using your own bodies fat to make your lips naturally look more shapely. The bonus is that the results last many many years.
In general, I avoid using permanent prosthesis because I find that the lips are such dynamic and sensitive structures, the end result is not natural.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Natural results depend mainly on technique, however, the appropriate type of filler is also important. For a soft, mild volumizing and enhancing result it is important to use a filler with a low G prime and high cohesivity. These terms relate to the cross-linking technology i.e. compressibility and spread. For lips it is best to use something soft and spreadable. Hyaluronic acid HA, a naturally occurring substance found in the connective tissues that cushions and lubricates. Because HAs are hydrophilic, they attract water from surrounding tissues, further augmenting soft tissue volume beyond what is expected from product implantation alone. For this reason, HA fillers are often excellent choices for enhancing lip volume. My favourites include Kiss, Saypha soft and Stylage S for the most natural results.
For tear trough or undereye filler, I prefer platelet rich plasma or an HA that does not pull as much water to prevent swelling. It has to haave the right balance of stiffness, cohesivity, duration of effect (about a year under the eyes), and relatively low swelling. Most importantly, injection technique is crucial.