Fasting Results & Data
Personal fasting data (N=1) from my own extended fasts — plus shared results from others around the world. Use this as a reference point, not a prescription. Everyone’s fasting response is unique 😄
My 10-Day Fast (Aug-Sep 2025)
Ketones and glucose data during the fast
Changes in weight (measured by my Withings floor weight sclae) and body composition (by Dexa scans)
These are my bloodwork results from the final hour of my 10-day water fast (Sep 4) on the left and another full panel after refeeding on the right (Oct 14)
Blood Results
Heart Health: 76 (pre-fast) -> 54 (fast) -> 92 (refeeding)
Fitness: 87 (pre-fast) -> 63 (fast) -> 85 (refeeding)
Metabolism: 78 (pre-fast) -> 65 (fast) -> 90 (refeeding)
Inflammation: 84 (pre-fast) -> 76 (fast) -> 95 (refeeding)
Sleep: 81 (pre-fast) -> 75 (fast) -> 84 (refeeding)
Hormone Balance: 90 (pre-fast) -> 81 (fast) -> 94 (refeeding)
Cognition: 87 (pre-fast) -> 78 (fast) -> 90 (refeeding)
Gut Health: 93 (pre-fast) -> 77 (fast) -> 94 (refeeding)
Endurance: 86 (pre-fast) -> 84 (fast) -> 86 (after refeeding)
Recovery: 94 (pre-fast) -> 90 (fast) -> 98 (refeeding)
Summary of All 10 Biomarker Categories: Pre-fast (Dec 2024) vs Fast (Sep 2025) vs Refeed (Oct 2025)
Biomaker Categories
Sleep: 81 (pre-fast) -> 75 (fast) -> 84 (refeed)
Fitness: 87 -> 63 -> 85
Endurance: 86 -> 84 -> 86
Cognition: 87 -> 78 -> 90
Metabolism: 78 -> 65 -> 90
Heart Health: 76 -> 54 -> 92
Gut Health: 93 -> 77 -> 94
Hormone Health: 90 -> 81 -> 94
Inflammation: 84 -> 76 -> 95
Recovery: 94 -> 90 -> 98
Total Testosterone
Total Testosterone
Feb 2010: 825 ng/dL (not on the graph)
Jan 2023: 1,036 ng/dL (not on the graph)
Jun 2023: 821 ng/dL (not on the graph)
Dec 2024: 969 ng/dL
Feb 2025, at the end of my previous 9-day fast: 131 ng/dL
May 2025: 564 ng/dL
Aug 2025, before this 10-day fast: 671 ng/dL
Sep 2025, at the end of last 10-day fast: 495 ng/dL
Oct 2025, after refeeding: 882 ng/dL
My typical daily electrolyte intake during extended fasts - water with pink salt, Ultima electrolytes (2-3 packets) and a bottle of San Pellegrino mineral water
Electrolytes, at the end of the fast
My 7-day (Nov 2024) and 9-Day (Feb 2025) Fasts
Body Weight: 7-Day Fast and Refeeding
Weight Changes: During My 7-Day Fast and Refeeding
Glucose: 7-Day Fast and Then Refeeding
RHR and HRV: 7-Day Fast and Then Refeeding
Body Weight: 9-Day Fast and Refeeding
Ketones: 7-Day Fast and Then Refeeding
GKI: 7-Day Fast and Then Refeeding
Respiratory Rate: 7-Day Fast and Then Refeeding
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
Cross-fast data
Ketones
Fat Loss: Dexa vs Withings Weight Scale
Collected Fasting Data from Others
Curated from publicly shared results and updated as new data becomes available