A vegan content creator spent 30 days pushing his daily fiber intake to nearly triple the U.S. recommendation — and the results suggest most people aren't undershooting by accident, they're undershooting by a lot.
As reported by Plant Based News, Mark Thompson, who runs the YouTube channel Mark Stache, documented a month-long experiment taking his fiber intake from around 20–25 grams per day to roughly 60–65 grams. Thompson already eats a mostly whole-food plant-based diet and was training for marathon events at the time.
The conventional wisdom on fiber tends to frame it as a digestive aid — something for regularity and not much more. Thompson's takeaway pushes against that narrow read.
Thompson explained that fiber has impacts beyond digestive health, according to his statements reported by Plant Based News. He noted that fiber influences blood sugar regulation, cholesterol levels, inflammation, and satiety.
To get to 60-plus grams, he layered three additions onto his existing diet: psyllium husk (mixed with water each morning), fiber-enhanced sodas as a swap for regular soft drinks, and Mission Carb Balance tortillas. Berries and beans rounded out the rest.
The first week was rough. Thompson reported two to three days of bloating, gas, and frequent bathroom trips before his system adjusted.
Thompson warned that jumping from a typical intake of 20-25 grams directly to 60 grams would likely cause noticeable digestive effects. He suggested that ramping up by five to 10 grams per week would have been gentler — a point that lines up with standard guidance to increase fiber gradually so the gut microbiome can adapt.
By week two, the side effects faded and something else took over: appetite suppression. Despite running roughly 40 miles a week and lifting, Thompson said hunger essentially disappeared between meals. He lost two pounds that week, though he flagged that hydration shifts could explain some of it.
The back half of the month brought steadier energy, fewer afternoon crashes, and what he described as reduced sugar cravings. One caveat: he wouldn't recommend the experiment to anyone deep in race training. The digestive turnover made for some inconvenient mid-run moments.
Thompson's landing point wasn't 60 grams. He concluded that 30 to 40 grams per day was the sustainable target — most of the benefits, less of the discomfort. He also stressed that psyllium husk only works with adequate water. He emphasized the importance of consuming psyllium husk with plenty of water to avoid counterproductive effects.
The wider context matters here. The baseline diet falls so short of fiber recommendations that an entire economy — supplements, fortified sodas, high-fiber tortillas — has emerged to fill the gap. A one-person experiment posted to YouTube isn't clinical evidence, but it does point at a useful middle ground: most people don't need to fibermaxx to 65 grams. They just need to stop landing at 15.
