There are two things that I have experienced since going keto in October of 2017:
I have not had a cold or flu since going keto. This is really remarkable since I ride the crowded NYC subway and work in an enclosed air office space everyday.
My tolerance for sun has changed dramatically. Before going keto, a five minutes in the sun would result in blotchy redness and itchy skin. Now I can go for much longer periods of time in the sun without the redness and itchiness and without any sunscreen. I used to jokingly say I was "allergic’ to the sun. That is no longer the case. I was never sure what about keto prompted this change but I had read something about Vitamin D as a possible factor. I love being able to have some short amounts of time in the sun without having to slather up in sunscreen.