Someone PM'd me and asked if I would comment on beans. They said beans are being touted as the food highest in RS, making up about 30% of the calories and so using beans would make a larger difference as you would only get about 70% of the calories listed.
Let's take a closer look at beans and RS.
First, most all my previous comments above apply, as you will see.
Second, to be accurate, as there are many numbers circulating on the internet about the amount of RS in foods, we will use the the current Standard Reference for Resistant Starch, which comes from this study.
Resistant starch intakes in the United States. J Am Diet Assoc. 2008 Jan;108(1):67-78.http://www.ncbi.nlm.nih.gov/pubmed/18155991
It compiled the data on RS from many studies. It also pointed out how earlier methods of calculating RS were not accurate and used animal models, test tube analysis, etc etc and how they have tried to correct for all of this. That is why there may be varying numbers out there and why we will use the Standard Reference.
So, knowing there are some limitations on the numbers and how they are analyzed and calculated, here is the info on beans and the amount of RS per 100 grams.
Legumes - Amount of RS per 100 grams
Beans, black/brown, cooked/canned - 1.7
Beans, kidney, cooked/canned -2.0
Beans, mung, cooked- 1.6
Beans, pinto, cooked- 1.9
Beans, white, cooked/canned -4.2
Chickpeas, cooked/canned- 2.6
Cowpeas, cooked - 0.6
Lentils, cooked- 3.4
Lima beans, cooked/canned- 1.2
Peas, mature, cooked/canned - 2.6
The average of these is 2.2 grams of RS per 100 grams.
However, lets use a "best case" scenario and use one of the higher foods tested, lentils, so we really see how big the impact of RS is and how the numbers work out.
Lentils are 3.4 grams of RS per 100 grams, which is about 1/2 cup and about 116 calories. The 3.4 grams would yield about 13.6 calories if it was totally digestible. That means 12% of their calories are RS, which they say you do not absorb. Subtracting that amount from the total would lower the calorie value from 116 to 102.4
However, RS yields about 2 calories per gram so using the 2 calories per gram, instead of lowering the calories value 12%, it would only lower it 6% and the calories would go from 116 to 109.
Some actual studies have shown that RS actually yields 2.2 to 2.8 calories per gram.
("Resistant starch averaged 2.8 kcal/g for all 24 subjects but only 2.2 kcal/g in the hyperinsulinemic subjects"
Resistant starch as energy. J Am Coll Nutr. 1996 Jun;15(3):248-54.)
So, if we used the 2.8 cal/gram, the calorie yield would only be lowered from 116 to 111.9, which is only 3.6%
And, that is a "best case scenario" using one of the higher legumes tests. However, according to the Standard Reference, the actual average amount of RS in beans is only about 2.2 grams per 100 grams, or about 2.2 grams per 1/2 cup cooked. So, the impact would be much lower.
On average, 100 grams of cooked beans is about 1/2 cup and about 115 calories and contains 2.2 grams of RS. The 2.2 grams of RS would yield 4.4 calories instead of 8.8 and so lower the total calories from 115 to 110.6, or about 3.8%.
At 2.8 calories per gram of RS, the 2.2 grams of RS would yield 6.16 calories instead of 8, lowering the total from 115 to 113.16 or about 1.6%
PS From the SR Database, here is the RS in 100 grams of other recommend foods
Potatoes, baked -1.0
Potatoes, boiled -1.3
Pasta, whole-wheat, cooked- 1.4
Rice, brown, cooked- 1.7
Barley, pearled, cooked -2.4
Buckwheat groats, cooked- 1.8
Millet, cooked- 1.7
Pita, wheat- 1.3
Whole-wheat bread -1.0
Tortillas, corn- 3.0
Sweet potatoes, cooked- 0.7
Yam, cooked -1.5