National Guard after WLS?
WLS is a surgery that excludes you from the armed services. I looked into it (the navy) as a chaplain and it's an exclusion period. But, I am not certain about the National and state guards. I would encourage you to call a recruitment office and tell them you just would like to know about medical exclusions.
When I found the documents, it was stated that they couldn't predict all food availability and water availability for someone with such specific needs.
Good luck