It looks like we’ve run out of diskspace on the server that hosts the forum, and that is why the Forum went down today.
I am temporarily reducing the size of images or attachments in new posts from 4MB to 1MB for now to reduce space, until we can move the forum to a new hard drive.
Thanks to the patreons who support the forum [see: http://patreon.ketogenicforums.com/ to help] we have accumulated enough money to be able to upgrade the site to a pair of 1TB solid state drives, and a magnetic drive for backups which we will be doing in the next couple of weeks. That should improve both the available storage, as well as the speed of the forum. Once that is done I will release the image/attachment constraints back to 4MB.
Sorry for the outage.