It is difficult to get long term data on the ketogenic diet because relatively few people are willing to stay on it long term. What little data is available:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7480775/
suggests it’s good for weight loss for short periods (~6 mo or less) but most people show no statistically significant difference at 12 months. Whether that’s a compliance/motivational issue or the natural outcome of sustaining the ketogenic diet seems difficult to tease out.