The autoimmune protocol (AIP) diet: a complete, evidence-based guide

By Yamila Acosta-Flamma, Stanford-trained Functional Nutrition Coach · 15 min · Medically-informed, not medical advice

What the AIP diet actually is

The autoimmune protocol — AIP — is a structured elimination-and-reintroduction diet built for people with autoimmune conditions. It grew out of the paleo diet, but it's stricter and, crucially, it's meant to be temporary. The idea is simple: for a set period you remove the foods most likely to provoke an immune response, give your body a chance to calm down, and then systematically add foods back to learn which ones your body actually reacts to.

That last part is what most people miss. AIP is not really about what you can't eat — it's a personalised experiment to find your individual triggers. The goal is never to stay on the elimination phase forever; it's to end up with the widest, most varied diet you can eat without symptoms.

The idea behind it: the gut–immune connection

Roughly 70% of your immune system lives in and around your gut. When the gut lining becomes more permeable than it should be — often called 'intestinal permeability' or 'leaky gut' — partially digested food proteins and bacterial fragments can cross into the bloodstream and keep the immune system on high alert. In someone with an autoimmune condition, that constant low-grade activation can feed the fire.

AIP targets this on two fronts: it removes foods thought to irritate the gut or provoke the immune system, and it loads the plate with nutrient-dense, gut-supportive foods — vegetables, quality protein, healthy fats, bone broth and fermented foods. Remove the triggers, nourish the repair.

Who it's for

AIP is designed for people living with a diagnosed autoimmune condition who still have symptoms despite standard care. I see it used most often for:

Hashimoto's thyroiditis and other thyroid autoimmunity
Rheumatoid arthritis and psoriatic arthritis
Inflammatory bowel disease (Crohn's and ulcerative colitis)
Psoriasis and other autoimmune skin conditions
Lupus, Sjögren's and mixed connective-tissue disease
Endometriosis and other inflammation-driven conditions

It is not appropriate for everyone. If you have a history of disordered eating, are underweight, pregnant or breastfeeding, or manage another medical condition, the elimination phase can do more harm than good without professional supervision.

The two phases (this is the whole method)

AIP has two phases, and skipping the second one is the single most common mistake:

Elimination — remove the trigger foods for 30–90 days, or until your symptoms clearly improve and stabilise.
Reintroduction — add foods back one at a time, slowly and methodically, watching for symptoms, to map your personal triggers and expand your diet again.

Think of it like resetting an overloaded circuit and then switching things back on one at a time to find the fault. Staying stuck in elimination forever isn't 'being disciplined' — it's leaving the job half-done, and it needlessly narrows your nutrition.

What to remove during elimination

During the elimination phase, AIP removes everything on a standard paleo diet plus several extra groups that are common immune provokers:

Removed	Examples	Why
Grains	Wheat, rice, oats, corn, quinoa	Gluten and other grain proteins can irritate the gut lining
Legumes	Beans, lentils, peanuts, soy	Lectins and saponins may increase gut permeability in some people
Dairy	Milk, cheese, butter, yoghurt	A common trigger; proteins like casein can drive inflammation
Eggs	Especially the whites	Egg-white proteins (e.g. lysozyme) can carry other proteins across the gut wall
Nightshades	Tomatoes, peppers, potatoes, aubergine, chilli	Contain alkaloids that may aggravate the gut and joints in sensitive people
Nuts & seeds	Including coffee and cocoa	Can be gut-irritating; reintroduced early as they're often well tolerated
Processed & additives	Refined sugar, seed oils, emulsifiers, alcohol	Pro-inflammatory and disruptive to the gut microbiome

What to eat instead

AIP is naturally focused on real, nutrient-dense food. The plate is far from empty:

Group	Best choices	Why it helps
Protein	Fish, shellfish, poultry, grass-fed meat, organ meats	Rebuilds tissue; oily fish is anti-inflammatory
Vegetables	All non-nightshade veg — leafy greens, broccoli, carrots, squash	Fibre and phytonutrients feed the gut and lower inflammation
Healthy fats	Olive oil, avocado, coconut, animal fats	Anti-inflammatory energy without provoking the gut
Gut support	Bone broth, fermented vegetables, sauerkraut, kombucha	Collagen and probiotics support the gut lining and microbiome
Fruit (moderate)	Berries, apple, citrus	Antioxidants — kept moderate to steady blood sugar

How long does the elimination phase last?

Most people run the elimination phase for 30 to 90 days. The honest answer is: until your symptoms clearly improve and hold steady, not a fixed number on the calendar. Many people notice changes — energy, digestion, joint pain, skin — within the first three to four weeks. Once you have a stable stretch of feeling better, you're ready to start reintroducing. If nothing at all has shifted after about six weeks of doing it properly, AIP may not be your lever, and it's worth reassessing with a practitioner rather than grinding on.

The reintroduction phase, step by step

This is where AIP earns its keep. Reintroduce one food at a time, so any reaction is unambiguous:

Pick one food (start with the ones most often tolerated — egg yolks, seeds, nut butters, ghee).
Eat a small amount, wait 15 minutes. No reaction? Eat a slightly larger amount.
Then stop eating that food for 3–5 days and watch — symptoms can be delayed. Track energy, digestion, skin, joints, mood and sleep.
No symptoms? The food is a 'yes' — add it back permanently.
Symptoms? Pull it back out, let things settle, and try again in a few months. Move on to the next food.

Does the AIP diet actually work? What the research shows

AIP is younger than the conditions it's used for, so the evidence is early and the studies are small — but what exists is genuinely encouraging:

In a 2017 study of inflammatory bowel disease, an 11-week AIP protocol helped a meaningful share of participants reach clinical remission — comparable to some medications, in a small group.
In a 2019 study of women with Hashimoto's thyroiditis, 10 weeks of AIP improved quality of life and lowered inflammation (hs-CRP), although thyroid antibodies and thyroid function themselves didn't change significantly.
Across studies, the most consistent wins are symptom relief, quality of life and markers of inflammation — not reversal of the disease itself.

So the honest read: AIP is promising for symptoms and quality of life, the trials are small, and it's best understood as a personalised tool rather than a proven cure. That's exactly why the reintroduction phase matters — you keep only the restrictions that earn their place for *you*.

AIP vs paleo — what's the difference?

Paleo removes grains, legumes, dairy and processed food. AIP starts from paleo and goes further — it also removes eggs, nuts, seeds, nightshades, coffee and alcohol during the elimination phase. The other big difference is intent: paleo is usually a long-term way of eating, while AIP is deliberately temporary, with reintroduction built in from the start.

Common mistakes

Never reintroducing — staying in elimination for months or years, needlessly restricting nutrition
Reintroducing several foods at once, so a reaction can't be traced to one food
Under-eating — AIP removes a lot, and people forget to replace those calories and carbs
Doing it with zero support for a complex condition, and missing nutrient gaps
Expecting overnight results, then quitting at week two before the reset has had time to work

Frequently asked questions

What foods can you eat on the autoimmune protocol?

Meat and poultry, fish and shellfish, all non-nightshade vegetables, moderate fruit, healthy fats (olive oil, avocado, coconut), plus gut-supportive foods like bone broth and fermented vegetables. You remove grains, legumes, dairy, eggs, nuts, seeds, nightshades, coffee, alcohol, refined sugar and processed food during the elimination phase.

Why can't you eat eggs on an autoimmune diet?

Egg whites contain proteins such as lysozyme that can help other proteins cross a permeable gut wall and reach the immune system, which may drive a reaction in sensitive people. Eggs are removed during elimination and then reintroduced early — many people tolerate them well and can add them back.

How long should you stay on the AIP diet?

The elimination phase usually lasts 30–90 days, or until your symptoms clearly improve and stay stable. After that you begin reintroducing foods one at a time. AIP is designed to be temporary — the aim is the widest diet you can eat without symptoms, not permanent restriction.

Is the autoimmune protocol diet legit?

It's a legitimate, structured elimination diet with early but encouraging research — small studies show improvements in symptoms, quality of life and inflammation for conditions like IBD and Hashimoto's. It's not a cure and the trials are small, so it's best used as a personalised tool alongside medical care, not as a replacement for treatment.

What is the best diet for autoimmune disease?

There's no single answer — it depends on your condition and your individual triggers. Many people do well on an anti-inflammatory, whole-food pattern (like the Mediterranean diet); AIP is a more structured way to find your specific triggers when standard advice hasn't been enough. The 'best' diet is the least restrictive one that keeps your symptoms quiet.

Can AIP help with Hashimoto's?

It may. A small 2019 study found 10 weeks of AIP improved quality of life and lowered inflammation in women with Hashimoto's, though thyroid antibodies and function didn't significantly change. If you take thyroid medication, work with your doctor — your dose may need review as inflammation settles.

Is AIP a forever diet?

No — and staying in the elimination phase forever is the most common mistake. AIP is a short-term experiment: eliminate, then reintroduce foods one at a time to learn your personal triggers, and rebuild the broadest diet you can tolerate.

Evidence & further reading

Evidence-based — but always confirm with your own clinician for your situation.