Low-FODMAP vs the GASP Score: what's the difference?

If you've gone looking for help with a sensitive gut, you've probably met two ideas: the low-FODMAP diet and — here on Toots & Trots — the GASP Score. They overlap, but they're not the same tool. Here's the plain version.

What low-FODMAP is

FODMAPs are a group of short-chain carbs (the letters stand for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) that pull water into the gut and get fermented by bacteria — which can mean wind, bloating and looser output for some people. The low-FODMAP approach, developed and lab-tested at Monash University, is a structured three-step process: cut high-FODMAP foods right back for a few weeks, then reintroduce them one group at a time to find your own thresholds, then settle into a long-term pattern built around the foods you tolerate.

Its strength is rigour. Foods are measured in a lab for their FODMAP content at set serving sizes, and it's usually done alongside a dietitian. If wind and bloating are your main problem, it's the most evidence-backed place to start.

What the GASP Score is

The GASP Score is broader. It's a modelled estimate — our opinion, drawn from the research — of how gentle a food is likely to be across five things at once: Gas, Agitation (irritation and urgency), Stool-loosening, Particle load (coarse residue like skins and seeds), minus Binding (the foods that help firm output up). FODMAPs feed into the Gas axis, but they're only one part of the picture.

That matters, because a low-FODMAP food isn't automatically gentle on every front. Popcorn is low-FODMAP, but it's high on particle load. A big glass of orange juice can be fine in a small amount yet loosening in a full serve. The GASP Score tries to capture that whole-food, whole-serving reality — especially for people whose gut has been surgically changed, like a J-pouch or an ostomy, where roughage and output speed can matter as much as wind.

Where they agree

Quite a lot, actually. Onion and garlic, wheat in big amounts, some beans and stone fruits tend to land harshly on both. If a food is high-FODMAP, it'll usually carry a higher Gas score from us too. Think of low-FODMAP as a well-measured slice of what GASP is trying to estimate across the board.

Where they differ

• Scope. Low-FODMAP looks at fermentable carbs. GASP also weighs irritation, looseness, roughage and binding.
• Method. Low-FODMAP is lab-measured. GASP is a modelled estimate — genuinely useful, but not a clinical measurement, and we're upfront about that.
• Preparation. GASP scores the same food differently depending on how it's prepared — boiled and drained, powdered, infused in oil, or raw with the skin on. Low-FODMAP testing uses set forms.
• Who it's built for. Low-FODMAP is aimed mainly at IBS. GASP is built first for J-pouch, ostomy and IBD output, then IBS and low-FODMAP eating.

So which should you use?

They're not rivals. If wind and bloating are your headline issue, a proper low-FODMAP process with a dietitian is a great, evidence-based path. If you also wrestle with urgent or loose output, coarse residue, or you've had surgery, the GASP Score adds the axes low-FODMAP doesn't cover — and you can layer the two. Plenty of people use low-FODMAP to find their carb thresholds, then lean on the GASP Score for everyday "what do I cook tonight" calls.

Whatever you use, the same rule holds: these are starting points, not verdicts. Tolerance is personal and it shifts over time, so reintroduce slowly and trust your own gut over any number — ours included.

The GASP Score is a modelled estimate, not medical advice, and low-FODMAP reintroductions are best done with a dietitian.