Resistant starch, discovered by British researchers in the early 1980s, looks like starch but acts like a fiber, meaning that it passes through the small intestine to the colon without being digested. It seems to improve efforts to lose weight, treat digestive problems, and prevent both diabetes and cancer.
There are several different forms of resistant starch:
• RS1 (Physically Inaccessible) is in oats, barley, wheat, seeds, and legumes
• RS2 (Resistant Granules) is in veggies and fruit including raw potatoes and green bananas (it is lost if the food is cooked)
• RS3 (Retrograded) is created by preparing hot, cooked carbohydrates like potatoes, pasta, bread, or rice and then allowing them to cool. Allowing rice to cool before eating it results in absorption of 50% fewer calories compared to eating it hot.
• RS4 (Chemically Modified) is created by food manufacturers who take regular starches, like wheat flour and treat or alter them to be more resistant.
The weight loss benefit from resistant starch occurs partly because it triggers hormones that make us feel fuller. People who ate resistant starch before a meal consume up to 300 calories less during the meal. Resistant starch also nudges the body to burn fat instead of carbohydrate for fuel while simultaneously shrinking the size of fat cells. In one study, people who got more than 5% of their daily carbohydrate intake from resistant starch (a total of 11-16 grams of resistant starch a day) increased the amount of fat that they burned by 20%. Mice fed resistant starch experience an increase in fat burned off up to 45% with most of it occurring in the belly.
Resistant starch is believed to decrease insulin levels, and the insulin response was significantly lower in people who ate RS-rich bread for three days when compared to people who ate the same amount of regular wheat bread for three days.
Resistant starch increases more “good” bacteria in the gut, which helps to boost metabolism and improvement in body weight. These “good” bugs also produce butyrate, which is a fatty acid that helps to strengthen the gut wall and prevent harmful bacteria and food particles from escaping the colon and causing inflammation and illness. Resistant starch is believed to have the potential to fight colon cancer, irritable bowel syndrome, diverticulitis, constipation, and colitis.
Unrolled and uncooked oats are likely the best source of resistant starch overall. Other cereals that provide resistant starch include puffed wheat, rice square cereal, corn flakes, and muesli. All legumes contain resistant starch, but white beans likely carry the most among beans. Among bread, pumpernickel holds the most resistant starch, but Italian is also a good source. Unlike isolated fibers, resistant starches are not usually accounted for on the Nutrition Facts label, so don’t bother looking there! If nothing else, this is a darned good excuse to eat pasta salad, rice pudding, and sushi.