plantbaes.net

Flagship

Fiber Load Checker for race week

Carb loading fails for plant-based runners when the carbohydrate target is hit but the fiber that comes with it is not cut. This checks the second number.

Sports dietitian review pending

Results land here: daily fiber vs the 15 g ceiling, plus specific low-fiber plant swaps.

A plant-based runner can hit 8–12 g of carbohydrate per kg and still show up to the start with a gut full of residue. That is the usual failure mode: the pasta is white, but breakfast was oats and chia, lunch was a grain bowl, and dinner kept the lentils. This checker totals fiber from the food table and compares it to a ~15 g/day working ceiling for the last 36–48 hours.

That ceiling is a plantbaes.net race-week heuristic, not a number ACSM published. It exists because during hard running, blood is diverted from the intestine and leftover fiber sits longer. de Oliveira, Burini, and Jeukendrup (2014) still describe that path to urgency and diarrhea.

Key takeaway:

Use ~15 g of fiber per day for the last 36–48 hours. It is a gut-management target, not a health guideline, and it is not an excuse to live on white starch all month.

Why a “healthy” day blows the budget

In this table, one cup of cooked steel-cut oats is 4 g of fiber. A tablespoon of chia is 5 g. Half a cup of chickpeas is 6 g. None of those plates looks reckless. Stacked, they spend the day before you add salad.

The swap is not “eat less.” It is “keep the carbohydrate, change the residue.” One cup of cooked white rice is 45 g of carbohydrate and 0.6 g of fiber. A white bagel is 55 g of carbohydrate and 2 g of fiber. Cream of rice (1 cup cooked) is 28 g of carbohydrate and 0.5 g of fiber.

How to use the checker

  1. Paste a real day — hotel breakfast, packed lunch, restaurant dinner, snacks.
  2. Add anything the mapper missed from the food list rather than hoping it counts as zero.
  3. Read the total against ~15 g.
  4. Take the named swap for every flagged row. Tofu for beans. White rice for brown. Maple for chia.

Then run the same sitting through the night-before dinner builder and the race-morning breakfast builder. Two “reasonable” plates can still add to 30 g.

Key takeaway:

Unmapped foods are listed, not guessed. A missing row is not 0 g of fiber.

Where the numbers come from

Fiber grams are stored on each food row. A language model only maps your sentence onto those slugs. If mapping fails, a keyword fallback still reads the same table. That is the site rule: numbers from the database, language from the model.

It will not invent a fiber count for “grandma’s dal” or decide that a restaurant grain bowl is “about 8 g.”

Mistakes this tool is built to catch

  • Oat loyalty. Oats are a training-block staple. In race week they are a fiber problem. Use cream of rice or a white bagel.
  • Protein-from-chili. Lentils do the job in January. Firm tofu does it on Friday.
  • Salad as virtue. A tower of kale next to white pasta still spends the ceiling.
  • Two-day sneak. Hitting 15 g on Saturday and 28 g on Sunday morning is still a race-week miss.

After the gun, beans return. There is no prize for living on white starch until Thursday. The longer list is in high-fiber foods that ruin a vegan carb load. GI context: preventing runner’s diarrhea.

What to do next

If the total is under 15 g, check that carbohydrate is still in the 8–12 g/kg band. If the total is over, swap the flagged foods and paste the day again. Then gut-train the race-week version of breakfast on at least one long-run morning using the gut-training protocol.

Frequently asked questions

How much fiber is too much before a marathon?
This tool uses a working ceiling of about 15 g of fiber per day across the final 36–48 hours. That is a plantbaes.net race-week gut heuristic, not an ACSM target. Individual tolerance varies.
Why do plant-based runners need this more than omnivores?
A typical plant-based diet starts race week much higher in fiber — often 35–50 g/day from legumes, whole grains, and vegetables. Generic taper advice says eat low fiber without naming the swaps.
Where do the fiber numbers come from?
From a reviewed food table stored with the site, not from a language model. The model only matches your meal description to that table. Unmapped foods are listed rather than estimated.
Will cutting fiber hurt my protein intake?
It does not have to. Firm tofu (150 g) is 16 g of protein and 1 g of fiber in this table. Lentils return after the finish.
Should I drop fiber for the whole training block?
No. Training-block fiber is useful. Use the ceiling for the last 36–48 hours and on a couple of dress-rehearsal long-run mornings, not for months.
What if a food cannot be mapped?
It is listed as unmapped. Do not treat a missing row as zero fiber. Pick a close food from the list or skip that item until it is in the table.
Does the 15 g ceiling include race-morning breakfast?
Yes. Breakfast still counts toward the day. A white bagel is 2 g of fiber in this table; oats plus chia can spend most of the budget before you leave the hotel.
Can I stay at 20 g if I tolerate it?
If you have rehearsed that intake on long-run mornings, you own that data. The tool still shows the table total so you can see the cost instead of guessing.

Sources

  1. de Oliveira, E. P., Burini, R. C., & Jeukendrup, A. (2014). Gastrointestinal complaints during exercise.
  2. Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). ACSM Joint Position Statement: Nutrition and Athletic Performance.
  3. plantbaes.net vegan carb-loading protocol.

Educational content only. Carbohydrate, fiber, iron, B12, and hydration needs vary. Consult a sports dietitian or physician for individualized guidance — especially if you have a GI condition, anemia, or a history of underfueling.