Here is an animation showing averaged male and female lips:
I am going to look at the differences between male and female lips them by dividing this page into 4 sections in which we will look at lip to nose distance, lip fullness, lip shape and the muscle moustache separately:
1. Lip to Nose Distance:
The distance between the top lip and the base of the nose tends to be longer in males and when a woman’s mouth is relaxed and slightly open she tends to show 2 – 4 mm of her upper teeth. This tooth exposure is considered attractive and can also lend a youthful appearance to the face. The lip to nose distance can be shortened with a lip lift. There are 3 types of lip lift procedure:
1. Bullhorn Lip Lift:
Also called the "subnasal lift". This is the most common lip lift type in FFS and involves making an incision at the base of the nose, a strip of skin is removed and the resulting gap is stitched shut lifting the lip. It leaves a small scar at the base of the nose. This procedure also rolls the top lip out a little exposing more of the lip and making it look fuller. The incision is only as wide as the nose so it can only lift about the middle third of the lip. This is not generally a problem unless you have very downward pointing corners to the mouth.
2. Gull Wing Lip Lift:
Also called a "vermilion advancement". This is where a strip of skin is removed from along the top edge of the lip and the gap is stitched shut lifting the lip. I personally do not recommend this procedure because it is a very noticeable place to have a scar and a particularly upsetting place to scar badly.
3. Corner Lift:
This is for people who have drooping corners to their mouths and involves taking out small sections of skin from above the corners of the top lip to lift them. There is a risk of noticeable scarring as there is with a gull wing lift but the corner lift scars are much shorter.
Apart from the scars I have mentioned and the usual risks of surgery, some people find that the lip drops to some extent after a while and it is possible that you will need a second lip lift to correct it. The main complication is scarring.
The Nolichi Rule:
It is important to bear in mind that the height of the chin needs to balance with the distance between the nose and mouth. In fact, on both males and females, the opening of the mouth is, on average, just under a third of the distance between the base of the nose and the base of the chin - the male may be taller overall in this area but the proportions between the lip nose and chin are the same in both sexes. I call this the "Nolichi rule" and you can read more about it in part 5 of my thesis.
The thing to bear in mind is that if you shorten a chin, you can make the lip to nose distance seem longer by comparison and conversely, if you shorten the lip to nose distance, you can make the the chin look proportionately taller so these features often need to be considered together. Rounding off the corners of a square chin often makes it seem shorter and in many cases that is all that is needed to make it work nicely with the mouth even though it might remain technically a little taller than average but in other cases, especially if the chin is very tall, you will need to consider shortening the height of the chin as well as rounding it.
2. Lip Fullness:
Female lips are, on average, a little fuller than male lips. You can't really see this from the front in photographs so if you look at averaged frontal views of faces (prototypes) like the one I have included above, the lips seem to be the same size for both sexes. This confused me at first as fuller lips do “seem” more feminine however, when I created prototypes by compiling profiles of faces rather than frontal shots, it became clear that female lips were indeed fuller because they bulge forwards more than male lips – in other words they are slightly more “pouty”. So female lips are not noticeably bigger when you see them from the front but they do bulge forwards more as seen from the side. When you see someone from the front in real life they are in 3D and you can see the lip fullness – it's only in 2D photos that the fullness is so difficult to see.
One thing to bear in mind with lip filling is that it is limited – you can't make thin lips full and luscious and trying to do so will make them look unnatural and can give you what is commonly called a “trout pout” or “duckbill” and there is always a risk that lip filling will not be completely symmetrical. There are 4 approaches to making the lips fuller:
1. Temporary Injectable Fillers:
These include hyaluronic acid which occurs naturally in the body and is marketed under names like “Restylane”, “Perlane” and “Juvaderm”. The length of time it lasts varies from person to person and from brand to brand but typically it lasts from 4 to 12 months (some brands are longer lasting because they contain more of the hyaluronic acid).
2. Permanent Injectable Fillers:
These include products like Aquamid gel and Artecoll. Some of them (including Artecoll) contain tiny plastic spheres and there is a risk that these can cause lumps to form (granulomas). They are not dangerous but they are difficult to remove. Permanent fillers tend to feel more solid in the lips
3. Patient's Own Tissue:
The advantage of using your own tissue is that there is no risk of rejection or allergic reaction. Fat can be taken from elsewhere in the body (often the belly) with liposuction and injected into the lips. The downside is that it tends not to be permanent. Some people do report permanent results after having it topped up a few times. Other options include using dermis (one of the deeper skin layers) or fascia (a tissue that covers muscle). These are removed as strips and threaded though the lips from one end to the other. They last very well but may thin a little with age. Using dermis or fascia will produce more swelling than injectable procedures and there is a risk of infection (as with all surgery) or that the graft won't take.
4. Artificial Implants:
Thin strips of a soft plastic material called Gore-Tex (Advanta is one brand) can be threaded through the lips from one end to the other. There are the usual surgery infection risks and patients can feel the implant under the skin to some degree though many say this is not a problem.
3. Lip Shape:
Apart from the fullness mentioned above female bottom lips appear to have a slightly different shape – they are a little more “V” shaped while male bottom lips have more of a “U” shape. I suspect this is not very significant in gender recognition. You could perhaps concentrate some lip filling towards the centre of the bottom lip to simulate or enhance this but I suspect it won't make much difference to your femininity.
4. The Muscle Moustache:
There are muscles that sit in the same area as a moustache (the obicularis oris and the triangularis). In some males these can be quite prominent and I call it the "muscle moustache". It is very much emphasised by hollow cheeks. Here’s a diagram of the muscles highlighted in brown:
This area is greatly improved by hormones and beard removal. The hormones reduce the muscle mass as well as filling the cheeks to bring them up to the level of the muscle moustache and hair removal simply reduces bulk in this area due to the large density of hairs removed.