You're bloated after every meal, your skin is staging a rebellion, and you're tired of hearing "it might be something you're eating" without anyone telling you what. So you drop $300-400 on an IgG food sensitivity panel that comes back flagging 37 foods, and suddenly you're eating nothing but rice and sadness.

Here's the thing those test companies won't tell you: the American Academy of Allergy, Asthma, and Immunology (AAAAI) explicitly states that IgG food panels are not validated for diagnosing food sensitivities. Elevated IgG to a food indicates exposure, not intolerance. You'd test positive for foods you eat regularly and tolerate perfectly.

The actual gold standard for identifying food sensitivities hasn't changed in decades, costs nothing, and works: the elimination diet with systematic reintroduction.

The Difference Between Allergy, Intolerance, and Sensitivity

These terms get used interchangeably on the internet, but they're distinct:

Food allergy (IgE-mediated): True immune reaction. Symptoms appear within minutes to 2 hours (hives, swelling, anaphylaxis, vomiting). Diagnosed via skin prick testing or serum IgE. This is NOT what elimination diets are for -- if you suspect a true allergy, see an allergist immediately.

Food intolerance (enzymatic): Missing or insufficient enzymes. Classic example: lactose intolerance from inadequate lactase. Symptoms are dose-dependent and GI-focused (bloating, diarrhea, gas). Generally reproducible and predictable.

Food sensitivity (non-IgE, non-enzymatic): The murky middle. Symptoms can be GI (bloating, pain, altered bowel habits) or extra-GI (headaches, fatigue, joint pain, skin issues). Onset is delayed (hours to days), making cause-and-effect hard to identify. No validated lab test exists. This is elimination diet territory.

The Three Phases: Eliminate, Challenge, Personalize

Phase 1: Elimination (2-4 weeks)

Remove the most common trigger foods simultaneously. The standard elimination includes:

  • Gluten (wheat, barley, rye, and related grains)
  • Dairy (all milk products, casein, whey)
  • Eggs
  • Soy
  • Corn
  • Peanuts and tree nuts
  • Shellfish and fish (optional -- more relevant for allergy than sensitivity)
  • Nightshades (tomatoes, peppers, eggplant, potatoes) -- include if joint pain or inflammation is a concern
  • Refined sugar and artificial sweeteners
  • Alcohol and caffeine (both are GI irritants that confound results)

Yes, this is restrictive. That's the point. Two to four weeks is enough time for existing inflammation to subside and symptoms to establish a new baseline. If you feel notably better during elimination, at least one eliminated food is likely a trigger.

If you feel no different after 4 weeks of strict compliance, food sensitivity is unlikely your primary issue. This is valuable information that saves you from years of unnecessary restriction.

A 2004 randomized crossover study in Gut (Atkinson et al., PMID: 14684564) found that elimination diets guided by food-specific IgG antibodies reduced IBS symptoms -- but notably, the elimination diet itself was the intervention. The IgG testing added minimal value over standard elimination protocol.

Phase 2: Reintroduction (6-8 weeks)

This is where the real detective work happens -- and where most people mess it up by reintroducing too many foods too quickly.

The protocol:

  1. Choose one food group to test (e.g., dairy)
  2. Eat a moderate serving on Day 1 (e.g., a glass of milk)
  3. Increase to a larger serving on Day 2 (e.g., yogurt and cheese)
  4. Eat normally (without the test food) on Days 3-4 and monitor for delayed reactions
  5. If no reaction by Day 5, that food is cleared. Move to the next food group.
  6. If symptoms return, remove that food and wait until symptoms fully resolve before testing the next group.

Keep a detailed food and symptom journal. Rate symptoms daily on a 0-10 scale for: bloating, abdominal pain, bowel habit changes, fatigue, headache, skin issues, and mood.

Why the waiting period matters: Non-IgE food reactions can take 24-72 hours to manifest. Testing a new food every day makes it impossible to attribute symptoms to the correct trigger. Patience during reintroduction is the difference between useful data and useless confusion.

Phase 3: Personalization (Ongoing)

Once you've identified your specific triggers, build a long-term diet that avoids those foods while maintaining the widest possible nutritional variety. This is NOT permanent maximum restriction -- it's targeted avoidance of identified triggers while freely enjoying everything else.

Retest trigger foods every 6-12 months. Sensitivities can change over time, especially if gut health improves through other interventions (probiotics, stress management, healing of underlying conditions).

Common Pitfalls That Ruin Results

Going too long on elimination: Extended restriction beyond 4-6 weeks risks nutritional deficiencies and can paradoxically increase food sensitivity by reducing immune tolerance. Elimination is diagnostic, not therapeutic.

Incomplete elimination: One "cheat" with gluten during the elimination phase can sustain an immune response for weeks, making the entire phase useless. Strict compliance for the full elimination period is non-negotiable.

Reintroducing multiple foods at once: "I had pizza, felt terrible, so I must be gluten-sensitive" -- but pizza contains gluten, dairy, tomato, and often soy. Which was the trigger? Test components individually.

Ignoring non-food variables: Stress, sleep deprivation, menstrual cycle, and exercise intensity all affect GI symptoms. If you reintroduce dairy during the most stressful week of the year, the resulting bloating might be stress, not lactose.

Confirmation bias: If you expect a food to cause problems, you'll perceive symptoms that aren't there. Ideally, have someone else prepare test foods so you don't know exactly when you're being challenged. In clinical settings, double-blind food challenges are the definitive test.

The FODMAP Variation

For people whose primary symptoms are IBS-related (bloating, gas, altered bowel habits), the low-FODMAP elimination diet developed at Monash University is a more targeted approach. Rather than eliminating all common allergens, it specifically removes fermentable carbohydrates that trigger GI symptoms through bacterial fermentation.

The FODMAP approach follows the same three-phase structure but tests specific carbohydrate subgroups (fructose, lactose, fructans, galactans, mannitol, sorbitol) rather than whole food categories. It's particularly well-suited for IBS patients and has stronger RCT evidence than general elimination diets.

A 2014 Gastroenterology study (Halmos et al., PMID: 24076059) showed a low-FODMAP diet reduced IBS symptoms in 76% of participants.

Working With a Professional

A registered dietitian (RD) experienced in elimination diets is strongly recommended, especially if:

  • You have a history of disordered eating (restriction-based diets can trigger relapse)
  • You need to maintain adequate nutrition while eliminating multiple food groups
  • You're unsure how to structure the reintroduction phase
  • You want to do a FODMAP elimination (Monash-trained dietitians follow standardized protocols)
  • You need help distinguishing between food sensitivity and other conditions (SIBO, enzyme deficiency, IBD)

When to Talk to a Pro

Consult a gastroenterologist or allergist if:

  • You suspect a true IgE-mediated food allergy (immediate reactions, hives, throat swelling)
  • Elimination diet reveals multiple trigger foods (this may indicate an underlying gut condition rather than multiple food sensitivities)
  • Symptoms persist despite comprehensive elimination (the issue may not be dietary)
  • You're losing weight or developing nutritional deficiencies during the process
  • You've developed food anxiety or orthorexia around "safe" versus "unsafe" foods

Frequently Asked Questions

How is an elimination diet different from just cutting out gluten or dairy? Cutting out one food is a guess. A proper elimination diet removes all common triggers simultaneously, then systematically tests each one individually. This controlled approach identifies triggers you might never have suspected while clearing foods you were unnecessarily avoiding.

Can children do elimination diets? Yes, but only under pediatric dietitian supervision. Children have higher nutritional demands per unit body weight, and poorly planned restriction can impair growth. Pediatric elimination protocols are typically shorter and more conservative.

Are food sensitivity tests completely worthless? IgG panels are not validated for food sensitivity diagnosis -- that's the official position of AAAAI, EAACI, and CSACI. However, some newer approaches (mediator release testing, ALCAT) are being researched, though none have achieved consensus validation yet. The elimination diet remains the reference standard.

Will my food sensitivities last forever? Not necessarily. Non-IgE food sensitivities can resolve, especially if the underlying trigger (gut inflammation, dysbiosis, stress) is addressed. Many people who react to a food during initial testing tolerate it after 3-12 months of gut healing. Periodic retesting is worthwhile.

A note from Living & Health: We're a lifestyle and wellness magazine, not a doctor's office. The information here is for general education and entertainment — not medical advice. Always talk to a qualified healthcare professional before making changes to your health routine, especially if you have existing conditions or take medications.