Summary
Ben Azadi brings back Dr. Boz for a deep dive into hemoglobin A1C testing, the dawn effect, Ozempic side effects, and her sardine fasting protocol. Dr. Boz explains the full metabolic science behind A1C — how red blood cells carry hemoglobin, what glycation does to arterial linings, and why testing at home matters. She outlines three metabolic levers she pulls for patients on keto. The sardine fasting segment covers her 72-hour sardine challenge in detail: eat only sardines in oil, anytime you want, for 72 hours. She explains how mastication triggers cholecystokinin and bile production, and why the first day is the hardest as the body ramps up its ability to emulsify and absorb fat. By day three, the glucose-to-ketone ratio is dramatically improved. Dr. Boz uses this protocol within her 21-day intensive ketogenic program, particularly for patients who have stalled on weight loss. The Q&A section addresses whether herring can substitute for sardines (yes — any SMASH fish works).
Key Points
- Sardine fasting protocol: 72 hours of only sardines in oil, eat whenever hungry, no limits on quantity
- The challenge starts at the first bite and must include eating a can at the 72nd hour
- Day one is hardest — bile production is insufficient, causing burping and GI distress
- By day three, ketone-to-glucose ratio is dramatically improved as the body adapts
- Best ketone numbers come the day after the 72-hour challenge — 3-4 mmol as a group average
- Glucose drops 15-30 points in three days of the sardine challenge
- Mastication is key — chewing triggers cholecystokinin and proper bile production for fat absorption
- The protocol works as a metabolic reset for insulin-resistant patients who have plateaued
- SMASH fish (sardines, mackerel, anchovies, salmon, herring) can all be used
- Ozempic causes significant muscle loss relative to fat loss — sardine fasting preserves muscle
- Dr. Boz includes this in her 21-day intensive ketogenic program for cancer-level metabolic intervention
Key Moments
The 72-hour sardine challenge — protocol details and what to expect
Dr. Boz outlines her 72-hour sardine challenge in detail. The challenge starts at the first bite and you must eat a can at the 72nd hour. Eat whenever hungry with no limits, but only sardines in oil. Day one is the hardest because bile production hasn't ramped up yet, causing burping and GI distress.
"One of the challenges is this 72 hours of only sardines. The sardine challenge starts with the first bite of sardines. And on the 72nd hour, you need to eat the last can of sardines."
Best ketone numbers come the day after the sardine challenge
Dr. Boz shares clinical data from her 21-day program. By day three of the sardine challenge, glucose-to-ketone ratio is dramatically improved. The peak benefit actually comes the day after — ketones hit 3-4 mmol as a group average, and glucose drops 15-30 points. Ketones beget ketones.
"The best ketone numbers of the whole thing are on the day after the sardine challenge. Their ketones are high, like I'm talking three to fours as a group."
Mastication triggers bile production — why eating sardines beats supplements
Dr. Boz explains the physiological mechanism behind the sardine challenge. Chewing (mastication) triggers cholecystokinin release and signals the parotid glands, which in turn stimulates bile production from the gallbladder and liver. This is why eating whole sardines works better than just taking MCT or omega-3 supplements.
"I had diarrhea. And they'll chirpy, chirpy. And I said, keep going because when your body makes these hormones, it will take a signal from what it has done recently. So the choocystokinin you eat today will be signaled in your parotid glands and when you masticate, when you chew. And that signal is missing when you have either been fasting too much or you've been eating a lot of particleized food without a high fat content. No better way to fix that than to chew on some sarins."
SMASH fish — sardines, mackerel, anchovies, salmon, herring all work
In the Q&A, a listener asks if herring can substitute for sardines. Dr. Boz confirms any SMASH fish works — sardines, mackerel, anchovies, salmon, or herring. The smaller the fish, the lower the mercury and the more absorbable the omega-3s.
"It's an acronym of SMASH. It's sardines, mackerel, anchovies, salmon, herring."
