For reference ‘1 can pinto beans’
One ‘large russet potato’
Google search says a russet potato is roughly 77% water weight when mashed.
I also found refried pinto beans is roughly 80%.
How do they have equal water absorption when one is substantially higher in carbs and the other in fiber?
Is it because a fiber is technically a carb, and carbs are good at absorbing liquid?
Answer
Most beans have more protein and fat. Proteins retain absorbed water.
Fiber is usually not considered a carb on nutrition labeling because it only indirectly yields small amounts of calories via microbial processes.