When your appetite drops on treatment with a GLP-1 medication, attention usually goes straight to protein. That makes sense, but there’s another nutrient that also tends to fall behind when plates shrink: fiber. Beans, greens, fruit and whole grains are exactly the foods that sometimes get left on the plate when your stomach fills up fast.

In this article, you’ll learn what fiber is, why it matters during this phase and where to find it in everyday foods from the Brazilian table.

What fiber is

Fiber is the part of plant foods that our bodies can’t fully digest. It passes through the gut practically intact and, along the way, plays several roles: it helps give stool bulk and consistency, supports how the gut works and feeds the bacteria that live there.

It’s found in beans and other legumes, greens, vegetables, fruit, whole grains, seeds and nuts.

Why fiber matters

In 2019, a series of systematic reviews and meta-analyses published in The Lancet, commissioned by the World Health Organization, looked at the link between carbohydrate quality and health. The researchers found that the reduction in risk for several important health outcomes was greatest when daily fiber intake was between 25 g and 29 g.

Building on this kind of evidence, the World Health Organization published a guideline on carbohydrates in 2023 that recommends at least 25 g a day of naturally occurring fiber for adults. The same guideline recommends that most carbohydrates come from whole grains, vegetables, fruit and legumes.

These numbers are population references. The right amount for you may be different, and it’s worth talking with your doctor or dietitian, especially if you have a bowel condition or another health condition.

Why it deserves attention during treatment

Eating less often means eating less of everything, including fiber-rich foods. And when protein becomes the priority, greens, fruit and beans can lose ground without you noticing.

On top of that, constipation appears among the most common adverse reactions in the U.S. prescribing information for semaglutide for weight management. Fiber, together with water and physical activity, is part of the habits that usually help the gut work well. If constipation is persistent or comes with pain, talk with your doctor.

Where to find fiber on the Brazilian table

The good news is that many fiber sources are already part of our routine:

Beans and other legumes. The short version of the Dietary Guidelines for the Brazilian Population notes that legumes, such as beans, lentils and chickpeas, are sources of protein, fiber, B vitamins and minerals. In other words, everyday beans help on both fronts: protein and fiber.
Greens and vegetables. Leafy greens, squash, carrots, chayote, okra, broccoli. Raw, cooked or in soups.
Fruit. Ideally whole, with the pulp and, when possible, the skin.
Whole grains. Brown rice, oats, whole-grain bread and pasta, corn.
Seeds and nuts. Chia, flaxseed, peanuts, nuts, in small amounts.

How to add it without upsetting your stomach

With a more sensitive stomach, a few strategies can make fiber more comfortable:

Go gradually. Adding a lot of fiber at once can bring gas and bloating. Adding a little each week tends to go more smoothly.
Drink water with it. Fiber works better when there’s enough fluid. Spread your water across the day.
Choose soft preparations. Cooked vegetables, soups and bean broths often go down better than big raw salads on queasy days.
Pair it with protein. Beans with an egg, lentil soup with shredded chicken, yogurt with oats and fruit: a small meal can add up protein and fiber at the same time.
Don’t trade protein for fiber. On small plates, the idea is balance. If you can only eat a little, start with the protein and fill in with vegetables.

Quick ideas for the day

Breakfast: plain yogurt with chopped fruit and oats.
Lunch: rice, beans, a portion of protein and some cooked vegetables.
Snack: a whole piece of fruit or a handful of nuts.
Dinner: vegetable soup with lentils or beans and shredded chicken.

Tracking helps

Writing down your meals for a few days helps you notice whether greens, fruit and beans are showing up or disappearing from your plate. Logging how your bowels are working also gives you useful information to bring to your appointment.

Fiber is one of those quiet nutrients that make a difference day to day. With small choices, you can keep it on your plate even while eating less.

Sources

Reynolds A, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 2019.
World Health Organization. Carbohydrate intake for adults and children: WHO guideline. WHO, 2023.
Brazilian Ministry of Health. Dietary Guidelines for the Brazilian Population: short version. 2018.
U.S. Food and Drug Administration. Wegovy® (semaglutide): prescribing information. FDA.

Fiber during treatment: where to find it and why it matters