https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716748/

A study I found from 2004 conducted on obese patients (higher than 35 bmi) who were placed on a ketogenic diet for 24 weeks with blood tests taken at intervals during the study. This was one of the only long-term studies I could find while researching.

All participants saw significant weight loss, loss of body fat, reduction in LDL cholesterol, and increase in HDL cholesterol. Blood glucose was also seen to improve.

DISCLAIMER: It should be pointed out that this study seems to have been conducted without the use of a control group and the sample size is relatively small, but it is one of the only studies I could find with results that span multiple months. Still, While the conclusions are very promising and sportive of the ketogenic diet, they should still be eyed with healthy scientific skepticism until replicated and with more rigor.