Three variants. One food.
The Sardine Protocol is the same metabolic event run at three doses. The 3-Day Reset is the on-ramp. The 5-Day is the standing monthly baseline for engaged practitioners — the cycle the protocol is actually designed around. The 7-Day Extended is the advanced cycle, run once or twice a year by the small subset of the cohort that runs it at all.
Which variant fits you?
Two questions. Pick the answer that describes you and follow the link.
Step 1
Have you ever done a sardine fast before?
No, this would be my first
Start with the 3-Day Reset. It is the on-ramp variant — long enough to drive the metabolic event, short enough to recover from cleanly, and the cycle that calibrates everything you need to know about how the protocol fits your physiology.
Read the protocol
Yes, I have done at least one cycle
Continue to the next question below.
↓ Continue
Step 2
How many clean 5-day cycles have you completed?
Fewer than three
The 5-Day Sardine Fast is your standing cadence. It is the cycle the protocol is actually designed around — engaged practitioners run one per month, indefinitely, and the gains compound across cycles.
Read the protocol
Three or more
You can run the 7-Day cycle, but most practitioners do not — the standing monthly 5-day continues to compound, and the 7-day is layered in once or twice a year at most. Read the 7-day page for the full picture before scheduling one.
Read the protocol
The three variants
Each protocol is a complete, citation-backed walkthrough — what it is, who it’s for, the mechanism in five minutes, the hour-by-hour, the refeed, and the common mistakes.
The on-ramp
BeginnerThe gateway cycle. Fully sufficient as a public guide: complete walkthrough, full safety detail, and the calibration cycle for everything that follows.
Read the 3-day protocol
The standing baseline
PractitionerThe cycle the protocol is designed around. Engaged practitioners run one per month, indefinitely. Public overview; optimization detail in Inner Circle.
Read the 5-day protocol
The advanced cycle
AdvancedOnce or twice a year. Stricter exclusions, more careful refeed, biomarker tracking. Most practitioners never need it. Public overview; protocol detail gated.
Read the 7-day protocol
At a glance
| 3-Day | 5-Day | 7-Day | |
|---|---|---|---|
| Duration | 3 days | 5 days | 7 days |
| Cadence | On-ramp / occasional | Monthly (standing baseline) | Once or twice / year |
| Who it's for | First-timers, gateway practitioners | Engaged practitioners with prior 3-day cycles | Advanced practitioners with prior clean 5-day cycles |
| Biomarker tracking | Optional | Recommended | Required |
| Physician oversight | Not required (healthy adults) | Recommended if any medical history | Required for any medical complexity |
| Refeed length | 3 days | 5 days | 7 days (structured) |
| Public guidance covers | Everything (no gating) | Full overview; optimization gated | Full overview; advanced detail gated |
Read this first.
Every variant has hard exclusion criteria — Type 1 diabetes, T2D on insulin or sulfonylureas, eating disorder history, pregnancy, BMI under 18.5, and several others. The Safety page has the complete list with the medical rationale for each. Read it before you start.
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A free 4-page PDF with the protocol overview, brand shopping list, day-by-day at a glance, refeed quick rules, and the warning signs that tell you to stop.
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Looking for the brand-by-brand sardine comparison? The buying guide is here.