u/andtitov

Hey folks! I shared how my blood biomarker categories changed over extended fasts in the past, and realized it might be a good idea to reshare them as there are some questions on this topic. Briefly, extended fasting is a huge stressor on the body, so it impacts many biomarkers.

I used InsideTracker’s biomarker categories, which combine 50+ markers into 10 health areas like Heart Health, Hormone Health, Inflammation and others. Each category gets a 0-100 score (100 = best) based on how close each marker is to its ideal range. For example, Heart Health includes ApoB, TSH, hsCRP, triglycerides, HDL, LDL, total cholesterol, and resting heart rate. So here are how my biomarkers changed over the 10 months - from Dec 2024 (before my 9- and 10-day water fasts) to Oct 2025 (after complete refeeding)

• Heart Health: 76 (pre-fast) -> 54 (fast) -> 92 (refeeding)
• Fitness: 87 -> 63 -> 85
• Metabolism: 78 -> 65 -> 90
• Inflammation: 84 -> 76 -> 95
• Sleep: 81 -> 75 -> 84
• Hormone Balance: 90 -> 81 -> 94
• Cognition: 87 -> 78 -> 90
• Gut Health: 93 -> 77 -> 94
• Endurance: 86 -> 84 -> 86
• Recovery: 94 -> 90 -> 98

And, in the chart, the black line shows Dec 2024, before my fasts, the red line marks the end of my last 10-day fast in Sep 2025, and the green line shows last month, after a month of refeeding. As you can see, the red line reflects how the body feels during extended fasting - not exactly thrilled, since fasting is a stressor.

Of course, this is N=1 data, and fasting (especially extended fasting) isn’t for everyone. But for me, it helped improve 8 out of 10 biomarker categories, so I just wanted to share my experience in case it’s helpful or interesting to others. If you did blood tests during extended fasts and after, please share your results.

Hey folks! To diversify the content here beyond peptides, I wanted to share my observations on visceral fat changes during my recent extended fasts (I shared these results in a fasting community, but I don’t believe I shared them here).

Visceral fat is the fat around your organs, and too much of it is linked to diabetes, heart disease, and inflammation. And extended fasting doesn’t just burn fat - it targets visceral fat first. So, here are my data (measured by Dexa scan)

7-day fast (Nov 2024):

• Total fat: 21.4 → 16.8 lbs (-4.6 lbs, 21% drop)
• Visceral fat: 0.62 → 0.21 lbs (-0.41 lbs, 66% drop)

9-day fast (Feb 2025):

• Total fat: 19.0 → 15.2 lbs (-3.8 lbs, 20% drop)
• Visceral fat: 0.61 → 0.24 lbs (-0.37 lbs, 61% drop)

10-day fast (Aug/Sep 2025):

• Total fat: 23.9 → 18.4 lbs (-5.5 lbs, 23% drop)
• Visceral fat: 0.62 → 0.37 lbs (-0.25 lbs, 40% drop)

While total fat consistently dropped around 20%, visceral fat fell 40-66% across these fasts - showing the body prioritizes the most harmful fat first. At the same time, the 10-day fast produced the smallest visceral fat drop, suggesting it may adapt over time and become more resistant to fasting. And if you’re wondering, yes - visceral fat comes back, as I stay in a calorie surplus to build muscle between fasts.

If you had a chance to measure your visceral fat, please share the results. Written by human, edited by AI.

Hey folks! I see some comments on autophagy, so I wanted to share my research findings - I think they might be interesting to the community. As you might know, autophagy is the body’s cleanup and recycling system for damaged cell parts. And it’s linked to longevity, metabolic health, lower inflammation, better brain function, and reduced chronic disease risk. And one of the most effective ways to activate it is fasting. Most numbers on the tables come from animal and cell studies, so treat them as rough estimates, not precise human data.

Basically, even when fully fed, we have basal autophagy. Cells typically recycle about 1-2% of their cytoplasm per hour, roughly 25-50% per day. That includes old mitochondria, misfolded proteins, and other cellular junk. It’s small per hour, but it never stops.

Fasting significantly boosts this process. Extending a normal 12-hour overnight fast to 16 hours - 16:8 intermittent fasting - can roughly double or triple autophagy compared to baseline. With short-term and extended fasts, autophagy may increase 5-10 times depending on tissue, meaning a large fraction of cellular material can be recycled within a day or two. Basically, longer fasts progressively ramp up autophagy.

These are my findings, and I hope it helps! As usual, thoughts and ideas are welcome.

Hi folks! A common comment I hear from people who’ve tried extended fasts is poor sleep. It shouldn’t be surprising - extended fasting is a stressor. During extended fasts, the body raises cortisol because it needs it to break down stored energy (increasing lipolysis and protein breakdown).

For example, here are my results from the last 10-day fast

• May 27, 2025 - 8.5 μg/dL
• Sep 4, 2025 (10-day fast) - 18.5
• Oct 14, 2025 - 10.8

So basically, cortisol more than doubled during my fast. And when cortisol is elevated, your body is more alert - not good for sleep. So, during your fasts, protect your sleep as much as possible - keep your room dark, minimize screens, maintain a consistent schedule, get enough electrolytes, don’t overtrain, use heat (hot showers or baths), and stay mentally calm.

I hope this helps. If you’ve measured your cortisol during extended fasts, please share your results.