“Depends”. This is a good tldr from NPR with the author of the book: https://www.npr.org/2026/04/11/nx-s1-5780065/gut-constipatio...

The primary study for kiwis notes: “Participants were instructed to consume the [green] kiwifruit without the skin.”

https://pmc.ncbi.nlm.nih.gov/articles/PMC10226473/

The skin does add both fiber and nutritional value (gold skin is more enjoyable then green IMO), but it may not be well tolerated by all.