You cannot assume this is an NIH study just because the website hosting the PDF is from the NIH. The NCBI is somewhat of an online repository of papers and citations, nothing more.

The study was published in the journal BMC Complementary and Alternative Medicine, and none of its authors are affiliated with the NIH, judging from their affiliation statement in the paper itself:

Author details

1 AOMA Graduate School of Integrative Medicine, Austin, TX 78745, USA.

2 NoviSci, Durham, NC, USA.

3 TrueNorth Health Center, Santa Rosa, CA 95404, USA.

4 TrueNorth Health Foundation, 1501 Pacific Avenue, Santa Rosa, CA 95404, USA.

The report appears rigorous, but it notes in several places that the data is not acquired in a rigorous way as it was not intended to be used to make such assessments.

As to controls:

>"the relative safety of water-only fasting is necessarily descriptive in nature as we did not identify a comparison group(s)"

It's a good paper.

I was left wondering why people attended the facility. A 9 day water only fast, with limited activity, sounds pretty extreme for a 70+ yo.

Bmc on the nih website nowadays basically hosting nih-founded research papers. Not just papers published from nih