Nutritionist Clau Gago: Fibre Is the New Diet Craze, but Ramp It Up Too Fast and Your Stomach Will Revolt

For years, protein was the star of the diet world. Now it's fibre's turn. Trends like "fibremaxxing" - loading your plate with as much fibre as possible - have crowned it "the new protein". And like every fad, this one has its casualties: people who ramp up the dose overnight and then wonder why their stomach feels like a balloon.

Nutritionist Clau Gago, who specialises in mindful eating and psychoneuroimmunoendocrinology, explains what's going on. Some fibre feeds the bacteria in the large intestine, which ferment it and produce gas in the process. "It's a normal process, but if we increase the amount a lot from one day to the next, we can feel more bloating and discomfort," she says.

How much is enough? Dietitian Patricia Ortega, who works with the World Avocado Organization, cites the recommendation of the Spanish Heart Foundation: 25 to 30 grams of fibre a day for adults, mainly from plant foods. Yes, an avocado organisation has an interest in us listening when it talks about plant foods - but the number comes from cardiologists. Enough fibre, according to Ortega, helps keep energy more stable, is linked to feeling full for longer, and is being studied for its role in weight control and heart and metabolic health.

Not all fibre is the same. Inulin, added to some supplements and "fortified" products, ferments very easily and can cause more gas. Portion size matters too. "With food, quantity matters. A small amount can agree with us, while a larger one can sit heavy," Gago says. "High in fibre" on the box means someone added something - not that your gut will thank you.

The recipe is slow and boring, and that's exactly why it works. Start with small portions spread across meals - say, a few spoonfuls of cooked lentils in your rice and vegetables. Stick with that amount for a few days and only increase it if it agrees with you. Drain and rinse canned legumes, because that removes some of the compounds that cause gas. Add a few oat flakes to your breakfast yogurt, have a piece of fruit as a snack, and drink water regularly. "If discomfort appears, I'd reduce the portion or try another source of fibre before continuing to increase the amount," Gago advises.

Bloating isn't necessarily fibre's fault. Gago points out that it can also come from eating more than we should, eating in a hurry or drinking fizzy drinks. Stress changes the rhythm of the gut and makes normal gas more noticeable, and for people with irritable bowel syndrome, poor sleep can bring more pain, inflammation or reflux.

And one line you don't cross on your own. If bloating is frequent, getting worse or doesn't go away after changing your diet, you need a professional. The same goes if you start cutting out foods for fear of discomfort: a doctor can find the cause, and a nutritionist can adjust your diet without unnecessary bans. Severe, sudden stomach pain calls for urgent medical help, not a new trick from the internet.