How Does Resistant Starch Help You Lose Weight?

Resistant starch is a type of dietary fiber that occurs naturally in certain foods and is added to some commercial food products. Among other health benefits, there is evidence linking resistant starch to improving weight loss. Knowing which foods are high in resistant starch and how to incorporate them into daily meals is useful when planning a weight loss diet.

Definitions

Resistant starch was first defined in 1982 and is so called because it resists digestion as it passes through the small intestine, fermenting instead in the large intestine. There are four types, known as RS1 to RS4, each of which resists digestion in a different way. Examples of foods containing RS1 include unprocessed whole grains, seeds or tubers; RS2 is found in raw potatoes and green bananas; and foods high in RS3 include cooked and cooled potatoes and cornflakes. RS4 starches are those that have been chemically modified to make them less digestible.

Sources

Foods naturally high in resistant starch include cooked navy beans, with 9.8 g per ½ cup; green bananas, with 4.7 g per medium peeled fruit; and cold potato, with 3.2 g per small potato, according to National Starch Food Innovation. Resistant starch is also found in legumes such as lentils, grains such as pearl barley and oatmeal, and cold pasta. A processed type of RS2, high amylose corn resistant starch, has been available in the U.S. since 1993. It is found as Hi-maize flour in food products such as breads and pastas.

Mechanism

Researchers have put forward a range of theories on how resistant starch might help weight management. A small study published in "Nutrition and Metabolism" in October 2004 suggested that resistant starch may boost the metabolism of fats after meals, and that replacing 5.4 percent of total dietary carbohydrate with resistant starch might decrease fat accumulation in the long term. In several studies with rats, published in "Obesity" in June 2006, researchers found that resistant starch might stimulate the gut hormones PYY and GLP-1, which affect satiety, or how full you feel after eating. Weight for weight, resistant starch is also lower in calories than other carbohydrates.

Significance

The American Dietetic Association states that Americans currently eat about 5 g of resistant starch per day, with breads and cereals, cooked pasta and vegetables as top sources. On a typical adult diet of 2,000 calories per day, including 1,000 calories from carbohydrates, increasing resistant starch intake to 5.4 percent of carbohydrates would mean eating around 13 g of resistant starch per day. However, for successful weight loss, taking in fewer calories than you expend is more important than the source of calories.