Would you rather have diarrhea or constipation?

A tough choice, shamefully skipped when people talk about cooking.
And yet, at the intake end of the digestive tract, there’s a cook, and at the exit end—a toilet cleaner.

And yes, when you go vegan, your poop radiates goodness and cosmic light. Although sometimes it also stinks so badly that birds fall out of the sky.

But there’s another very important issue connected with a plant-based diet and the exit end of things.
Fiber.

Fiber is crucial for the gut microbiota, which is key to our overall health (including mental health). It’s also an important support in managing body weight—real support, not the kind promised by “miracle drugs” in ads—because it creates a feeling of fullness while providing very few calories. It helps prevent and treat obesity and diabetes.

A superfood.

And it also regulates intestinal peristalsis—in other words, bowel movements.

One of the effects of a meat-heavy diet (and even more so when that meat comes from highly processed foods) is a tendency toward constipation.
In simplified terms, constipation is a sign of insufficient fiber in the diet.

And here’s a major health advantage of a plant-based diet, which by default contains more fiber.
This is also an important guideline, regardless of whether you’re eating plant-based or not when choosing products from the shelf: the one with more fiber will almost always be healthier.

One of the reasons I like textured soy protein so much—the so-called “sawdust cutlets”—is that its two main components are protein and fiber, fifty-fifty.

Can you eat too much fiber? I’ll answer like a dietitian: it depends.
If you really try, you can overdo anything, including fiber—but you really have to try.

That said, when switching to a plant-based diet, or in general from a low-fiber to a high-fiber diet (which is absolutely one of the basic dietary recommendations), a side effect like diarrhea can occur, simply because the body isn’t used to that amount of fiber. This effect is temporary and harmless.

It’s also worth being aware that products like konjac pasta, used for example in weight loss diets and made EXCLUSIVELY of fiber, can cause you to get absolutely blown seven fields over—I know this from experience.

Disclaimer: I am not a doctor or a dietitian, just a chef who treats evidence-based nutrition as an important part of culinary knowledge. I am a member of the scientific, professional Polish Society of Lifestyle Medicine.
My nutritional knowledge is sufficient for me to be aware of my own ignorance, and above all, to recommend that if you need medical or dietary advice, you consult a doctor or a certified dietitian.
Internet celebrities, food technologists, and even chefs are definitely not authorities in this field.