9-Day Water Fast - February 2025
Complete data from my 9-day water fast (Feb 3-12, 2025) and 5 days of refeeding: daily weight, ketones, glucose, sleep, heart rate, HRV and blood work. Part of my fasting results series - see all my fasts and cross-fast comparisons on the Results page. N=1 data, a reference point, not a prescription.
Weight (scale)
Ketones (Keto-Mojo glucose-ketone meter)
RHR and HRV (Oura ring)
Sleep and Readiness (Oura ring)
Glucose (Keto-Mojo glucose-ketone meter)
Respiratory Rate (Oura ring)
These are my bloodwork results from the final hour of my 9-day water fast. I tested 52 biomarkers — sometime before my 9-day water fast in February, and then just 30 minutes before breaking the fast. The chart below highlights changes in some key markers (focus on Feb ’25 data; I retested a few in May)
12 biomarkers shifted out of their “optimized” range after the fast — including potassium, vitamin B12, TIBC, ferritin, testosterone, free testosterone, SHBG, white blood cells, total cholesterol, LDL cholesterol, triglycerides, and ApoB
Blood results
Glucose, insulin, and HbA1c all went down exactly as expected
The other 37 biomarkers showed no significant changes from my pre-fast levels, and almost all stayed in the “optimized” range — see examples below