BuddyPress.org

@Gpo1

Since groups are currently “owned” by a single user–that means that every group is started by one user who is the admin–it is not possible to create groups without any members.

Although a plugin could be written that automatically creates a group using the Site Admin’s ID for the creator_id in the groups table. Thus, the Site Admin would be the initial group admin and its only member–until other members were automatically added to it based on the datum in a given profile field.