FODMAP Elimination Phase: Step-by-Step

Before You Start

The elimination phase is the first of three phases in the low-FODMAP diet. Its purpose is to reduce your overall FODMAP intake to a level that allows your symptoms to settle, establishing a clear baseline. Before starting, it is worth getting a confirmed IBS diagnosis from your doctor and, ideally, a referral to a FODMAP-trained dietitian.

Stock your kitchen with low-FODMAP staples before day one. This includes proteins like chicken, fish, eggs, and firm tofu; grains such as rice, oats, and quinoa; low-FODMAP vegetables like carrots, zucchini, capsicum (bell pepper), spinach, and potato; fruits such as strawberries, blueberries, oranges, and unripe bananas; and lactose-free dairy or plant-based alternatives.

What to Eliminate

During the elimination phase, you remove foods high in any of the five FODMAP subgroups. Fructans are found in wheat, rye, onion, garlic, and many processed foods. GOS (galacto-oligosaccharides) are concentrated in legumes and pulses. Lactose is present in milk, soft cheeses, and ice cream. Excess fructose occurs in honey, apples, pears, mangoes, and high-fructose corn syrup. Polyols include sorbitol (stone fruits, some sweeteners) and mannitol (mushrooms, cauliflower).

Reading ingredient labels becomes important. Common hidden sources of FODMAPs include inulin and chicory root fibre (fructans), fruit juice concentrates (excess fructose), and sugar-free products containing sorbitol, xylitol, or isomalt (polyols).

Meal Planning and Practical Tips

Plan your meals for at least the first week before starting. Batch cooking is highly effective — prepare large portions of low-FODMAP soups, stews, or grain bowls and freeze individual servings. This prevents the decision fatigue that often leads to abandoning the diet.

Use garlic-infused olive oil to replace the flavour of raw garlic (fructans are water-soluble but not oil-soluble). The green tops of spring onions (scallions) can replace onion in many recipes. Maple syrup is a low-FODMAP sweetener that can replace honey.

Keep a daily symptom diary from day one. Rate bloating, pain, and stool consistency each day so you can objectively track whether symptoms improve over the 2–6 week elimination window.

How Long Should Elimination Last?

The recommended duration is 2–6 weeks. Most people notice meaningful symptom improvement within 2–3 weeks. If you see no improvement after 4–6 weeks of strict adherence, FODMAPs may not be the primary driver of your symptoms, and you should consult your dietitian or gastroenterologist about alternative approaches.

Extending the elimination phase beyond 6 weeks is discouraged. Prolonged restriction reduces prebiotic fibre intake, which can decrease beneficial Bifidobacteria populations and narrow the diversity of your gut microbiome. The elimination phase is a diagnostic tool, not a permanent diet.