Since it sounds like you have already done quite a bit of digging, you have seen most of everything there is to see. If this has not been enough to convince you, I'm afraid no one can help you. Whatever you may mean by 'conclusive evidence' clearly does not exist. 

As for what has convinced me in particular, my own changes and the similarities of the changes I have seen in the faces of others who have tried to capture theirs.

There is hardly evidence that diet affects facial development in any large amount. Just look at any before and after picture of kids treated under orthotropic principles or anyone treated under Dr. Mew. I challenge you to find one before and after of a young kid who's face changed through diet.

In the same way your brain grow and therefore places pressure on your skill to grow and your eyes grow and places pressure on your orbitals to grow, your tongue sits on the roof of the mouth allowing the maxilla to grow forwards. Through what mechanism does diet play a part in any of this? How does your diet give you a wider maxilla/palate, a more upward and forward maxilla, if there are no forces keeping the maxilla wide, up, and forwards? The only factor I see that diet plays is how much you grow, it's a known fact that undernourishment/malnourishment stunts growth as in height. So maybe a lackluster diet can lead to a undeveloped face in terms of how much bone you actually have, but I doubt that it plays any significant role in facial form in terms of how upwards, forwards, and wide the maxilla is.

/community/community/main-forum/hey-guys-mewing-doesnt-work-sarcasm-age-15-21-before-after-itt/

Here is possibly the best result achieved through mewing, and he started at 18, basically done growing for the most part and in the final development stage. How does diet achieve this if there is no mechanism or force to push the maxilla up and forward?

Developing a midline diastema after mewing for 3 weeks is what made me decide to keep going, since Mew said it was a sign of expansion (although it took me 3 years to get measurable and noticeable expansion).

Posted by: sinned

There is hardly evidence that diet affects facial development in any large amount. Just look at any before and after picture of kids treated under orthotropic principles or anyone treated under Dr. Mew. I challenge you to find one before and after of a young kid who's face changed through diet.

In the same way your brain grow and therefore places pressure on your skill to grow and your eyes grow and places pressure on your orbitals to grow, your tongue sits on the roof of the mouth allowing the maxilla to grow forwards. Through what mechanism does diet play a part in any of this? How does your diet give you a wider maxilla/palate, a more upward and forward maxilla, if there are no forces keeping the maxilla wide, up, and forwards? The only factor I see that diet plays is how much you grow, it's a known fact that undernourishment/malnourishment stunts growth as in height. So maybe a lackluster diet can lead to a undeveloped face in terms of how much bone you actually have, but I doubt that it plays any significant role in facial form in terms of how upwards, forwards, and wide the maxilla is.

/community/community/main-forum/hey-guys-mewing-doesnt-work-sarcasm-age-15-21-before-after-itt/

Here is possibly the best result achieved through mewing, and he started at 18, basically done growing for the most part and in the final development stage. How does diet achieve this if there is no mechanism or force to push the maxilla up and forward?

A softer diet means more people leave their mouth hanging open which means their face is more affected by gravity causing it to grown down and backwards. If a child is breastfed sufficiently so that it develops tongue strength as well as eats a sufficiently tough diet it will naturally develop proper oral posture with the entire tongue resting on the palate. This forces the jaws to grow up and forwards which creates a healthier (perfect airways and occlusion) and more attractive facial appearance.

Posted by: Camus

If you've seen convincing evidence that mewing is legitimate, please post it here. It would be helpful to have one place where people can go for reassurance that this stuff works, instead of having to sift through 1000+ random posts. I'm pretty sure nothing like that exists yet.

I made a blog just for this reason and in few posts I will be covering this exact topic. 

Personally, I have yet to see any conclusive evidence that mewing/upwards tongue posture helps facial development. In fact, there are some valid concerns that this type of upwards pressure would be bad for facial development. I also haven't found good evidence that chewing gum is actually healthy, or even helps in facial aesthetics (could lead to TMJ, ulcers, puffy cheeks, grinding, etc). This website is chock full of dubious anecdotal evidence and grainy before/after pictures where it's hard to tell if anything actually happened.

There is allot incorrect information floating around that is being falsely attributed to mewing. Dr. Mew never recommends applying pressure. Everything he talks about relates to gentle subconscious forces. And by the way chewing gum is part of the official orthotropic treatment and does give results. Again some people have taken it to extreme from 1 hour daily to 5 hours.

More and more, the scientific evidence I'm seeing shows that the real key to functional genetics (e.g. straight teeth) is in your diet and your ancestor's diets. If anyone's interested in this school of thought, I recommend the book "Deep Nutrition." Of course, this isn't at all mutually exclusive to posture. I'd really like to believe that Dr. Mew is on the right track and knows what the correct tongue posture is, but it doesn't seem like he has a good body of evidence to support his claims yet.

I am going to look at this, I think another reason the Mews do not cover is that there allot of people living today with poor immunity/health and I think illness in general effect growth negatively, but you got to wonder why especially in the face, right? This is where Dr. John Mew's research is very handy in answering this question.

That being said... just because I haven't seen enough evidence doesn't mean it doesn't exist. If you guys are convinced, let me know what convinced you! It would be immensely helpful if we could try to consolidate evidence in one place.

Please visit my blog if you are interested in reading more about this topic. I try my best to cover all the information out there in a comprehensive manner.

http://www.aljabri.com/blog/

Posted by: sinned

There is hardly evidence that diet affects facial development in any large amount. Just look at any before and after picture of kids treated under orthotropic principles or anyone treated under Dr. Mew. I challenge you to find one before and after of a young kid who's face changed through diet.

Of course there is, Dr. Weston Price has allot of research on this where he documented the change in diet on the faces of the Inuit people. As for the work of Dr. John Mew I am researching it as we speak and it is amazing. He is growing jaws forward and making faces shorter in kids with simple techniques such as tongue posturing, nasal breathing, gum chewing, proper swallowing, and keeping mouths shut. 

In the same way your brain grow and therefore places pressure on your skill to grow and your eyes grow and places pressure on your orbitals to grow, your tongue sits on the roof of the mouth allowing the maxilla to grow forwards. Through what mechanism does diet play a part in any of this? How does your diet give you a wider maxilla/palate, a more upward and forward maxilla, if there are no forces keeping the maxilla wide, up, and forwards? The only factor I see that diet plays is how much you grow, it's a known fact that undernourishment/malnourishment stunts growth as in height. So maybe a lackluster diet can lead to a undeveloped face in terms of how much bone you actually have, but I doubt that it plays any significant role in facial form in terms of how upwards, forwards, and wide the maxilla is.

Chewing hard foods gives you stronger muscles and that helps in two ways. It insures that the lower jaw grows to its optimal size through muscle stimulation and that it stays closed so it dose not drop and drag the tongue down with it removing any support for the upper jaw. I explain this process in this topic:

http://www.aljabri.com/blog/what-is-improper-facial-growth-or-craniofacial-dystrophy/

I'm also sceptical, but I decided to try mewing as an experiment for a year. I'm positive that some changes to the face might be possible, but I don't expect any miracles like some people here do. 

My problems are just my jaw pain and my slightly receding chin, whereas anything else is in the normal range (Average maxilla, intermolar width of 41mm, broad face, good straigth teeth even though I never had braces) If mewing can help with these two problems... good. If not then mewing is either not for me or really might just not work at all. 

@abdulrahman and @pame I wrote a long response and then it got flushed down the toilet because of an error, so I'll give a brief run down of what was in the response.

- I attribute diet theory to Weston Price, who as far as I know didn't talk about how hard the diet was, correct me if I'm wrong. He was more about how nutritionally dense the food was, not necessarily it's toughness and that affect on the jaws. Who I relate to mewing theory as the op addressed is Dr. Mike Mew, who is the one that popularized chewing and mewing.

- I'm aware chewing affects the jaws significantly, here's even a post I made about it  /community/community/main-forum/masseter-affects-length-not-just-width/

- Weston Price's research is hardly conclusive as it makes a lot of assumptions from observations that lacked the things we know today. He made correlations between diet and primitive people's developed faces, but doesn't consider all the other factors that go into facial development. Primitive people are for example likely to breastfeed longer, be exposed to less allergens, have stronger immune systems, less allergies, etc. Observing and comparing a population of Inuit being westernized with their primitive relatives is not as conclusive as an individual before and after, being westernized means that your diet is not only being changed, but so is your whole upbringing and environment.

-We need to distinguish what diet does and does not affect, lackluster (nutritionally and calorically, not toughness) diet can lead to stunted growth, usually do to being underweight or starving. In the same way, diet can probably stunt one's maxillary and mandibular growth.

- So here's the distinction, your maxillary placement ie how forwards and upwards it is, is for the most part affected by the tongue. The tongue holds up the maxilla so no matter what diet you have if your tongue has been on the roof of your mouth all your life and you've got perfect (tongue/oral) posture, no amount of bad diet can give you downwards growth or crowded teeth. However a bad diet I think affects how much bone you actually have, in other words a bad diet leads to shorter stature which usually means smaller/shorter bones of course. In a similar way a bad diet can probably lead to a smaller maxilla or mandible, essentially you are stunted and more juvenile/neotenous. This is just my assumption, I'm sure genetics play a role as well but I feel like diet can stunt your facial development in this specific manner.

edit: How much bone you have in the mandible is probably also affected by how strong and big your masseters are. Also good article : ) @abdulrahman

Posted by: sinned

@abdulrahman and @pame I wrote a long response and then it got flushed down the toilet because of an error, so I'll give a brief run down of what was in the response.

- I attribute diet theory to Weston Price, who as far as I know didn't talk about how hard the diet was, correct me if I'm wrong. He was more about how nutritionally dense the food was, not necessarily it's toughness and that affect on the jaws. Who I relate to mewing theory as the op addressed is Dr. Mike Mew, who is the one that popularized chewing and mewing.

........

@sinned Yes Dr. Price documented the changes well, but he was off on the cause, I mention this in the second post I made about this topic:

At the time Dr. Price theorized, that the new local diet they started consuming after resettlement was deficient in minerals and nutrition and caused their condition. While his observations were very important his conclusions were incorrect. Their new diet was nutritionally richer; it just was too soft, leading them to develop CFD.

http://www.aljabri.com/blog/what-is-the-proof-that-craniofacial-dystrophy-is-real/

I also go into some of the points you make in a third post about why is the body growing larger when the jaws are growing smaller.

http://www.aljabri.com/blog/why-are-jaws-growing-smaller-if-humans-are-growing-larger/

Also good article : ) @abdulrahman

Thanks

Posted by: sinned

Through what mechanism does diet play a part in any of this? How does your diet give you a wider maxilla/palate, a more upward and forward maxilla, if there are no forces keeping the maxilla wide, up, and forwards? The only factor I see that diet plays is how much you grow, it's a known fact that undernourishment/malnourishment stunts growth as in height. So maybe a lackluster diet can lead to a undeveloped face in terms of how much bone you actually have, but I doubt that it plays any significant role in facial form in terms of how upwards, forwards, and wide the maxilla is.

/community/community/main-forum/hey-guys-mewing-doesnt-work-sarcasm-age-15-21-before-after-itt/

Here is possibly the best result achieved through mewing, and he started at 18, basically done growing for the most part and in the final development stage. How does diet achieve this if there is no mechanism or force to push the maxilla up and forward?

If your diet is full of seed oils (read: Deep Nutrition) your cells will not get nutrients the way they are supposed to. Sugar and too much carbs make the effect even worse. It can inhibit K2 vitamin for example. And when that happens you can even grow bone cells in parts of the body where they shouldn't be. Now contrast that with drinking bone broth often and never consuming seed oils + limiting sugars.

The difference is massive.