# Why does the carbs / fiber ratio decrease after cooking?

According to USDA, medium grain raw brown rice has carbs and fiber at a ratio of 76g / 3.4g = 22.4.

When cooked, the ratio changes to 24g / 1.8g = 13.3.

Are these numbers wrong, and if not, why does this ratio change in favor of fiber? Mere dilution shouldn't change this ratio.

EDIT: The missing 0 hypothesis seems to be the most plausible explanation so far, but I'd like to find sources completely independent from USDA to be sure. All of the sources I found just copy USDA directly or indirectly.

• If you boil 100 grams of rice do you have 100 grams of rice or does the rice "suck" the water increasing it's weight? Jul 25 '19 at 12:01
• @SZCZERZOKŁY of course, but the question is about the ratio
– user18825
Jul 25 '19 at 16:11
• Insoluble fiber can absorb water. I wonder if the 'cooked' number isn't the dry weight of the fiber, but the weight with the water. Protein wouldn't do the same thing, so it'd look like you gained fiber.
– Joe
Jul 25 '19 at 22:54
• @Joe "cooked" weight is cooked weight. The question is about the ratio though.
– user18825
Jul 26 '19 at 0:40
• @MaxB : I'm talking about the cooked weight of the fiber. If they consider it to be the weight with absorbed water, it's going to increase. (the fiber measurement is in grams, so it's a weight)
– Joe
Jul 26 '19 at 16:06

When you cook things using water you add mass that have 0 calories. Some food, like rice, absorb that water. Hence boiling 100 grams of rice increase final mass to around 300 grams.
Then again you measure the 100 grams carbs and it's 3 times less than your starting points because you never added additional carbs in the process.

The fiber amount is IMHO wrongly calculated because 3,4 gram divided by 3,16 (ratio of carbs in 100 grams before and after cooking) is 1,075. Probably someone rounded up the 75 wrong and had 1,8 instead of 1,08.

• The missing 0 hypothesis seems to be the most plausible explanation so far, but I'd like to find sources completely independent from USDA to be sure. All of the sources I found just copy USDA directly or indirectly.
– user18825
Jul 25 '19 at 21:34
• @MaxB I would say that the data it's rather solid across other sources rather than copied. I've checked in few different languages and they usually give between 3,3 or 3,5 grams of fiber. Jul 26 '19 at 7:11