Thinking About A Low-FODMAP Diet? Here's Exactly What You Need To Know

Thinking About A Low-FODMAP Diet? Here's Exactly What You Need To Know Hero Image
Photo: © Brooke Lark

"My doctor diagnosed me with irritable bowel syndrome (IBS) but then had no idea how to treat it other than to tell me to reduce my intake of gassy foods" my 34-year-old patient Maria said during her initial visit. "When he reached for his prescription pad, I knew I needed a second opinion." Post-meal bloating, gas, abdominal pain, and sometimes diarrhea made social occasions unbearable for Maria. "I'd freak out if there wasn't a bathroom nearby," she confessed, "and avoided several parties for fear something embarrassing would happen."

And as a medical doctor who specializes in gut health, I've had numerous patients like Maria. Fortunately, there is a tried-and-true way to treat IBS and other gut conditions without drugs or other invasive procedures: a low-FODMAP diet. And while the low-FODMAP diet isn't exactly a newcomer to the wellness world, it can still seem very complicated and be pretty difficult to execute. Here's the information you need to know to get started, plus seven expert tips on how to make your new diet a success.

How do I know if a low-FODMAP diet is right for me?

FODMAPS is an acronym for the unwieldy phrase: fermentable oligo-, di-, and monosaccharides and polyols (sugar alcohols). That's a mouthful, but the common thread is these short-chain carbohydrates attract water and don't absorb well in your small intestine, instead heading to your colon, where bacteria have a field day quickly fermenting them. Symptoms of FODMAP intolerance include burping, bloating, constipation, diarrhea, and flatulence: very similar to what occurs with IBS and other gastrointestinal (GI) disorders. A research team in Monash University in Melbourne, Australia, created the low-FODMAP diet, which eliminates frequent food offenders that contribute to or exacerbate IBS and other gut problems. The results were impressive: One study found a low-FODMAP diet improved symptoms in about 68 to 76 percent of IBS patients—results I've seen in my own practice.

IBS aside, a low-FODMAP diet helps a variety of gut conditions including Crohn's disease, celiac disease, inflammatory bowel disease, and even small intestinal bacterial overgrowth (SIBO: another problem that causes bloating, abdominal pain, constipation, and diarrhea).

What are high-FODMAP goods and why are they a problem?

Patients get great results because a low-FODMAP diet treats the underlying causes, not just the symptoms. Let's briefly look at high-FODMAP foods and why they can become a problem.

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  • Lactose: About two-thirds of the world's population is deficient in lactase, the enzyme that breaks down the milk sugar lactose. Undigested lactose pulls water into your intestines, causing diarrhea, gas, bloating, and pain.
  • Fructose: Of course high-fructose corn syrup (HFCS) contains this bad-news sugar, but so does fruit, honey, maple syrup, agave syrup, and certain fruits including red apples, pears, and mangos.
  • Fructans: Also called fructooligosaccharides (FOS), this common prebiotic is found in artichokes, leeks, garlic, onions, and jicama. The highest fructans intake, however, comes from wheat. We lack enzymes to break down fructans, leading to bloating, gas, and pain.
  • Galactans: High-galactan foods include legumes. You guessed it: We lack the enzyme to break down galactans.
  • Sugar alcohols: Polyols naturally occur in some fruits and vegetables but more often as added sweeteners in sugar-free gums, mints, cough drops, and medications. Anything ending in –ol (like erythritol and xylitol) is a polyol.

Why is the low-FODMAP diet so challenging?

All of these categories aren't necessarily bad unless you struggle with FODMAP intolerances. While I recommend most patients eliminate dairy and wheat, others like sugar alcohols (especially xylitol) and fructans (as prebiotics) can be perfectly healthy. With a low-FODMAP diet you'll completely eliminate these high-FODMAP foods for four to six weeks. If you let even a little creep in, you'll find it harder to identify your food culprits. Many patients like Maria notice a difference almost immediately. After about a month, we test high-FODMAP foods by reintroducing them one at a time. Maria learned that while she could occasionally tolerate some high-FODMAP fruits, a few foods like dairy and wheat were permanently off the table.

Here's how to succeed on your low-FODMAP diet:

"Initially sticking with a low-FODMAP diet felt a little challenging," Maria told me during our third consultation, "but not having those OMG I've got to run to the bathroom NOW and other post-meal woes made it worth sticking to." For her and other patients, I recommend these seven tips that make managing gut conditions like IBS and sticking to a new eating plan a little bit easier:

1. Keep a journal.

Tracking your food intake becomes an excellent way to pinpoint where high-FODMAP foods and other food intolerances might creep in and target major offenders.

2. Keep a list nearby.

Know what you can eat. Low-FODMAP foods include:

  • Fruits: bananas, blueberries, lemons, oranges, and tomatoes
  • Vegetables: spinach, Swiss chard, cucumber, carrot, and zucchini
  • Meat: eggs, poultry, fish, red meat, and tofu
  • Grains: gluten-free grains (buckwheat, quinoa, brown rice, oatmeal, popcorn)
  • Dairy alternatives: nut milks (except cashews)

3. Remember, eating FODMAPs has a cumulative effect.

The more high-FODMAP ingredients you eat at a single meal, the stronger your symptoms will likely be. But unfortunately, that does not give you permission to let a "little" high-FODMAP food slip in during your elimination phase.

4. Scrutinize labels.

FODMAPs sneak into processed foods, even healthy ones. Maria learned her chewing gum had xylitol as its sweetener, and the protein powder she used every morning had inulin, a high-fructan FODMAP.

5. Get the app when you're on the go.

The Monash University Low-FODMAP Diet App makes selecting low-FODMAP foods easy when you're at a restaurant, a social occasion, and the grocery store.

6. Work with a trained nutritionist or physician.

Patients tell me how easy complying with the diet can be when I supervise their progress, create an individualized diet plan, and tweak as necessary. This especially becomes important during the elimination phase, whereas Maria learned that sneaky high-FODMAP ingredients can derail your best efforts. Find a health practitioner in your area who can help you optimize a low-FODMAP diet.

7. Don't surrender hope.

If your symptoms are so pervasive that you don't notice differences immediately with dietary changes, a diagnostic breath test can help determine what causes your underlying symptoms.

I'd love to share more strategies to reverse IBS and other gut conditions to lose weight and feel great with my free Quick Start Guide to a Happy Gut.


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