A 3 day sardine fast, sometimes spelled saedine, is a short mono-food reset where you eat only sardines, drink water, and keep flavors simple. People use it to simplify choices, test satiety, and get a high omega-3, high protein break from ultra-processed foods. This is not medical advice. If you have kidney disease, gout, fish allergy, a history of eating disorders, are pregnant or breastfeeding, or take medications that interact with high sodium, speak to a clinician first.

Why sardines

• Protein dense for strong satiety and stable energy
• Rich in omega-3 fats that support normal inflammation control
• Bones in the can provide calcium
• Good sources of B12, vitamin D, selenium, iodine
• Small forage fish are typically low in mercury and widely available

What you will need

• 12 to 18 tins of sardines with bones and skin, packed in water, brine, or olive oil
• Sea salt or iodized salt
• Lemon juice, mustard, vinegar, or hot sauce for minimal seasoning
• Still or sparkling water
• Optional plain black coffee or unsweetened tea
• Optional zero calorie electrolyte mix without sugar or caffeine

Ground rules

• Eat only sardines for food during the 3 days
• Season lightly with the items listed above
• No sweeteners, no sauces with sugar or flour, no dairy, no grains, no vegetables, no fruit
• Hydrate to thirst, then a bit more
• Stop when comfortably full at each meal

How much to eat

Aim for roughly 1.2 to 1.8 grams of protein per kilogram of body weight per day for these 3 days. Most 100 gram servings of sardines provide about 20 to 25 grams of protein. For many adults this works out to 4 to 6 small tins across the day. Choose water packed if you prefer lower calories, olive oil packed if you need more calories to feel satisfied.

Sample schedule

Day 1

• Breakfast: 1 to 2 tins, drained if in oil. Add lemon and salt.
• Midday: 1 to 2 tins with a splash of vinegar or mustard.
• Evening: 1 to 2 tins, keep seasoning minimal.
• Fluids: Water throughout the day. Optional black coffee or tea in the morning.

Day 2

• Repeat pattern. If hungry between meals, have half a tin instead of reaching for drinks with additives.
• If you feel heavy, switch to water packed tins and drain well.

Day 3

• Keep the same meal rhythm.
• If you experience palate fatigue, rotate pack styles. Example: one meal in water, one in olive oil, one in brine with lemon.

Electrolytes and salt

Sardines already contain sodium. Most people do well salting to taste and drinking water. If you feel lightheaded or crampy, add a pinch of salt to a glass of water once or twice in the day. Avoid high dose potassium supplements unless advised by a clinician.

Choosing the can

• Bones and skin intact provide more calcium and micronutrients
• Check labels for simple ingredients
• If histamine sensitivity is a concern, choose brands with shorter supply chains and the freshest date codes you can find

What you may feel

• Day 1: Strong satiety, reduced food noise, possible coffee-like breath from protein metabolism
• Day 2: Clearer hunger signals, steady energy, or mild fatigue if calories are too low
• Day 3: Palate boredom, which is part of the reset. Many notice easier portion control by now

If you feel unwell, dizzy, or have persistent headaches, stop and return to normal eating with simple foods.

Common questions

Can I work out
Yes, but favor light training. Walking, mobility, and easy strength work are fine. Hard intervals are better saved for after the reset.

What about supplements
If you take prescribed medications or essential supplements, continue as directed by your clinician. Avoid adding new fat-soluble vitamins during the fast.

Is mercury a concern
Sardines are among the lower mercury fish. This plan is only three days, which further limits exposure.

What about fiber
Three days without fiber is usually tolerable for healthy adults. If constipation occurs, increase water, walk after meals, and consider switching to water packed tins if you relied on oil packed.

Refeed on Day 4

Reintroduce foods gently to avoid digestive upset.

• Breakfast: Eggs and fruit, or yogurt and berries
• Lunch: Sardines with cooked potatoes or rice and some cooked vegetables
• Dinner: Lean protein of choice with vegetables and olive oil
• Continue to hydrate. Keep sauces simple for one more day.

Troubleshooting

I am too hungry
Add a tin at the next meal, choose olive oil packed for more calories, or shorten the fast to two days.

I feel queasy from the oil
Drain the can, switch to water packed, and chill the tins before eating.

Fishy breath
Rinse with water and lemon, drink more water, and consider parsley tea or plain green tea.

Salt feels high
Use water packed tins, drain brine, and season only with lemon or vinegar.

Who should not do this

• History of eating disorders
• Kidney disease, gout, or known purine sensitivity
• Fish or shellfish allergy
• Pregnancy or breastfeeding
• Anyone advised by a clinician to avoid high sodium foods

A simple shopping list

• 12 to 18 sardine tins
• Lemons
• Sea salt or iodized salt
• Mustard or vinegar
• Still and sparkling water
• Optional plain coffee and tea

Why three days is enough

Three days is long enough to simplify choices, feel satiety from a protein rich food, and notice how much routine eating you do out of habit rather than hunger. It is short enough to avoid social disruption and micronutrient gaps that appear with longer mono-food plans.

The takeaway

The 3 day sardine fast is a structured, temporary reset that trades variety for simplicity. If you try it, keep rules tight, listen to your body, and refeed with care. The goal is not perfection. The goal is to learn how much less noise you can have when food is simple, protein is adequate, and decisions are few.