What Is Resistant Starch?

Dietary fiber has long been an overlooked nutrient compared to protein, with its brag-worthy status in health conversations and food marketing. Yet fiber is starting to have its moment.

Fiber’s lack of appeal may be due to its history as a constipation fix. Yet, its health benefits extend to cholesterol management, blood sugar control, satiety, weight management and microbiome health.

Resistant starch is another carbohydrate attracting attention. It is found in plant-based foods, cooked and cooled foods, and many processed foods. Though technically a type of starch, resistant starch behaves more like fiber in the body.

Potential Benefits of Resistant Starch

Like fiber, resistant starch can help slow carbohydrate digestion and reduce the rise in blood sugar after eating.

Resistant starch can’t be completely digested, so it passes intact to the colon, where it is fermented by gut bacteria. Through this process, resistant starch acts like fermentable fiber and a prebiotic, supporting overall gut health. Research suggests that resistant starch may improve insulin sensitivity in people with diabetes, metabolic syndrome or obesity.

The fermentation process also may support weight management as resistant starch provides fewer calories. Fully digestible carbohydrates provide 4 calories per gram versus approximately 2 to 3 calories per gram from resistant starch.

Research also points to potential anti-inflammatory effects and cholesterol reduction. However, more research is needed to make practical dietary recommendations.

Adding Resistant Starch to Your Diet

There are five types of resistant starch (RS1–5). These are found naturally in foods, formed through cooking and cooling, and by food processing.

Natural Sources

Whole grains and legumes are a key source of RS1, thanks to their tough outer cell wall that shields the starch during cooking and digestion.

RS2 is found in raw foods such as uncooked oats (as in overnight oats) and unripe bananas. It also is found in green banana flour and unmodified potato starch, which can be added to yogurt bowls and smoothies for potential health benefits.

Cooking and Cooling

When you cook foods like pasta, potatoes or rice and then refrigerate them for at least 24 hours, some of the starch reorganizes into RS3, which resists digestion. Fortunately, you don’t have to eat these foods cold, as reheating retains resistant starch. RS3 also forms in frozen breads.

Processed Ingredients

RS4 is formed intentionally when certain starches are processed for use as food additives. These are used to improve textures and food shelf-life. It’s not just a useful food additive. Clinical trials suggest it may have a positive role in supporting metabolic health. Examples of RS4 include resistant maltodextrin, soluble corn fiber, modified wheat starch and other starches found in foods such as protein bars, cereals, baked goods, tortillas and sauces.

RS5 is formed when a certain type of starch binds with fat. This is done in food processing to improve texture and extend the freshness of baked goods. There’s currently no easy way to estimate how much RS5 is in a food.

How Much Resistant Starch Matters?

Unlike dietary fiber, which has strong evidence for the recommended 25 to 35 grams daily, there are no official recommendations for resistant starch intake. Some research suggests that consuming 15 to 30 grams of resistant starch per day may aid in improving gastrointestinal health, insulin sensitivity and blood sugar control. However, more research is needed. The estimated average intake of resistant starch is about 4 grams per day.

Because resistant starch is naturally found alongside foods with fiber, increasing fiber intake is an easy way to get more of both. The following table includes foods that provide resistant starch.

As interest grows in the health benefits connected to fiber, resistant starch offers additional benefits. Together these carbohydrates can support health, but you can thank resistant starch for making leftover pasta a more nutritious meal.