How to avoid concentration underestimation with dry beans?

Only weigh the dry starting material and the final drained product.

A practical technique for accurately managing nutrient concentration when dealing with ingredients like dried beans or pasta that absorb water is to separate the nutrient calculation from the final yield weight denominator. Specifically, one should include the weight of only the dry starting material when calculating the total nutrient contribution (the numerator). Subsequently, for the denominator used in calculating per-serving density, one should only weigh the final product after it has been drained of excess cooking water. This avoids mistakenly inflating the final weight by including water that did not contribute nutrients, which would otherwise lead to an underestimation of the actual nutrient concentration.