I’m 40 Hours Into a Water-Only Fast. What Should I Expect?

If I’m on day 2 (now 40 hours) of a water-only fast, what should I expect of my Insulin and Polypeptide levels (as detected by my MRAN Device)? Should they be rising or falling?

During a water-only fast at 40 hours, both insulin and pancreatic polypeptide (PP) levels are expected to change in response to fasting physiology.

1. Insulin (Expected to Decrease)

• Insulin levels should be falling significantly by this point.

• Why?

  • Without food intake, glucose levels drop, reducing the need for insulin.

  • The body shifts to fat metabolism and ketone production, further lowering insulin.

  • By 40 hours, insulin levels may be at the lower end or below your baseline range.

2. Pancreatic Polypeptide (Expected to Increase Slightly)

• Pancreatic polypeptide (PP) may increase in response to prolonged fasting.

• Why?

  • PP is released in response to fasting, stress, and vagal stimulation (which occurs when the digestive system is empty).

  • It helps regulate digestive enzyme secretion and slows gastric emptying.

  • Studies suggest PP rises during fasting and peaks around 48 hours, likely due to its role in energy balance.

What to Expect Next?

• Insulin will likely remain low as long as fasting continues.

• Pancreatic Polypeptide may peak around 48 hours, then stabilize.

• By 72 hours, you may enter deep ketosis, with insulin at a low steady state and PP possibly declining.

What should I expect of my Blood Sugar Coefficient and my Urine Sugar Coefficient at this time also?

During a 40-hour water-only fast, here’s what you can expect for your Blood Sugar Coefficient and Urine Sugar Coefficient based on fasting physiology:

1. Blood Sugar Coefficient (Expected to Decrease)

• This coefficient is likely dropping as blood glucose levels fall due to the absence of food intake.

• Why?

  • Initially (~first 12–24 hours), the body relies on glycogen stores for glucose.

  • By 24–48 hours, glycogen is mostly depleted, and blood sugar stabilizes at a lower level as the body shifts to fat metabolism and ketone production.

  • If insulin levels are also low, blood sugar may still be within a stable fasting range but lower than your fed-state baseline.

2. Urine Sugar Coefficient (Expected to Remain Low or Near Zero)

• Urine sugar should remain low or at zero unless there was a prior glucose spike.

• Why?

  • Under normal conditions, the kidneys reabsorb glucose, preventing it from spilling into urine.

  • During fasting, blood sugar is generally lower, so there’s little to no excess glucose to excrete in urine.

  • If urine sugar is present, it could indicate delayed glucose clearance or metabolic dysregulation.

What to Expect Next?

• Blood Sugar Coefficient: Likely to reach its lowest steady state between 48–72 hours as ketones become the dominant fuel.

• Urine Sugar Coefficient: Should remain very low or zero, unless there’s an unusual glucose release (e.g., stress response or underlying metabolic issue).

Also at this stage (40 hours) of the water-only fast, all my low trace element levels (zinc, phosphorous, copper and cobalt) have increased, but calcium and selenium have decreased. Is this also in the realm of the expected?

Yes, your observed shifts in trace elements at 40 hours of fasting are largely within the realm of expected metabolic adaptations. However, the specific increases in zinc, phosphorus, copper, and cobalt, alongside decreases in calcium and selenium, provide important clues about your body’s physiological adjustments during fasting.

Why Have Zinc, Phosphorus, Copper, and Cobalt Increased?

1. Mobilization from Tissues (Bone, Liver, and Muscle)

• Zinc & Copper:

  • Fasting triggers catabolism of stored proteins (muscle, liver proteins like metallothionein, and enzymes), releasing bound trace elements into circulation.

  • The liver stores both zinc and copper, and fasting-induced autophagy (cellular cleanup) may liberate them.

  • Copper may also be freed from ceruloplasmin, leading to temporary elevations.

• Phosphorus:

  • Phosphorus is stored in bones, ATP, and cellular membranes (phospholipids).

  • Glycogen depletion during fasting results in phosphorus release because as glycogen is broken down, phosphate groups are also freed.

  • Increased fat metabolism may also release phosphorus from cell breakdown.

• Cobalt:

  • A component of vitamin B12, cobalt levels may increase as stored B12 is metabolized.

  • Some increases in gut bacterial activity could also contribute.

Why Have Calcium and Selenium Decreased?

1. Reduced Dietary Intake & Immediate Plasma Utilization

• Unlike trace elements that are easily mobilized, calcium and selenium are more tightly regulated and may decrease due to:

  • Lack of dietary intake (no new calcium or selenium entering circulation).

  • Renal handling changes during fasting, where calcium excretion may increase slightly due to diuresis.

  • Selenium, primarily stored in the liver, may be actively used for antioxidant defense (e.g., glutathione peroxidase activity) during fasting-induced detoxification.

2. Calcium Shift into Cells & Bones

• Parathyroid hormone (PTH) rises slightly in fasting, signaling calcium to shift into bones and intracellular compartments rather than remain in the bloodstream.

• This could explain lower circulating calcium levels.

Conclusion:

✅ Expected Changes:

• Increases: Zinc, phosphorus, copper, cobalt → Released from tissues and cellular breakdown.

• Decreases: Calcium, selenium → Redistribution, excretion, or increased utilization.

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