The 5 Worst Foods For Your Stomach

While researching my new book, 21-Day Tummy, I learned so much about an emerging field of fascinating science: that both weight loss and digestive health are tied to eating specific foods that balance your gut bacteria and lower inflammation (and skipping foods that do the opposite).

As I embarked on the plan myself—I lost 10 pounds in just three weeks!—one thing that surprised me the most was how many seemingly healthy foods may be aggravating your stomach without your even realizing it. These "belly bullies" throw your gut bacteria out of whack, cause inflammation, and may pack on the pounds. Here are some of the top offenders.

Milk and High-Lactose Dairy Foods

One of the most cutting-edge components of the 21-Day Tummy is the avoidance of FODMAPs, or rapidly fermentable carbohydrates that can aggravate your gut. Some people aren’t sensitive to any FODMAPs, some experience symptoms after eating only certain ones, and other people develop gradually worsening effects with each exposure. Lactose, found in all animal milks, is the best-known FODMAP. Lactose is broken down in the small intestine by an enzyme called lactase. Our bodies produce less lactase as we get older (since its main purpose is to help babies digest breast milk), which means dairy foods that contain lactose can torment our tummies over time even if they didn’t before. If you think your tummy doesn’t respond well to milk, try swapping it for unsweetened almond milk in cereal or smoothies.

Found in: milk, regular (non-Greek) yogurt, soft cheeses, dairy-based desserts.

Garlic, Onions, and High-Fiber Cousins

The body’s inability to digest a kind of fiber, called fructan, in these foods can cause flatulence. This fiber seems to cause more symptoms than some other kinds, but that may simply be because we eat so much of it. If you rely on garlic and onions regularly to add flavor to dishes, try experimenting with savory herbs like rosemary, thyme, and sage instead.

Found in: grains (barley, wheat), vegetables (artichokes, onions, garlic), legumes (black beans, kidney beans, soybeans), additives (inulin).

Excess Fructose (in Apples, Honey, Asparagus)

We’re always taught fruits and veggies are good for us, but for some with stomach issues the excess fructose found in some of these healthy foods can cause problems. Foods with a lot of fructose (another FODMAP) compared with glucose can contribute to gas, bloating, and diarrhea. A 2008 study in the Journal of Clinical Gastroenterology found that patients with IBS who followed a non-fructose diet had fewer symptoms.

Found in: certain fruits (apples, mangoes, watermelons), certain vegetables (asparagus, sugar snap peas), sweeteners (high-fructose corn syrup, agave nectar, honey).

See More: 7 Worst Foods for Your Belly »

Carb-Dense Foods

As I explained in my blog post last week, not all carbs are bad for weight loss. The 21 Day Tummy reveals some breakthrough science about “carb-light” versus “carb dense” foods. Carb-dense foods can mess with your gut flora, leading to an imbalance that can trigger inflammation and weight gain. Foods are considered carb-dense if they have a high ratio of carb grams relative to their weight. Only 23 percent of a small potato, which many consider a “bad” carb, is carbohydrate. By contrast, a “healthy” rice cake is 80 percent carbohydrate, which is very dense! 

Found in: bagels, bread (including whole-grain breads), crackers, pasta, cereals, white rice, pretzels.

Beans and Nuts

We lack the enzyme to break down a FODMAP in these foods, so our gut bacteria must digest them, which produces gas.

Found in: Most beans and some nuts (cashews, pistachios).

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