What is a Resistant Starch?: How to improve blood sugar without giving up carbs

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You’ve probably never heard of a resistant starch but it’s an easy blood sugar hack that can be integrated seamlessly into your daily routine. It involves using a cooking and cooling process (that you likely already use for leftovers) to alter the chemical composition of the food and reduce the blood sugar impact.

Resistant starch is a type of carbohydrate that resists digestion in the small intestine and ferments in the large intestine, acting similarly to dietary fiber. This fermentation process feeds beneficial gut bacteria, promoting various health benefits.

How Is Resistant Starch Formed?

Resistant starch occurs naturally in certain foods and can also be increased through specific cooking and cooling processes. For instance, cooking starchy foods like potatoes, rice, or pasta and then cooling them in the refrigerator alters their chemical structure, increasing their resistant starch content. Reheating these cooled foods does not diminish this effect; in fact, it can further enhance the resistant starch levels.

Impact on Blood Sugar Levels

One of the notable benefits of resistant starch is its positive effect on blood sugar management. Since it isn't digested in the small intestine, resistant starch doesn't cause rapid spikes in blood glucose levels. Instead, it leads to a more gradual release of glucose (like a fiber), helping to maintain steady blood sugar levels. Research has shown that consuming resistant starch can help improve insulin sensitivity, which is beneficial for anyone looking to improve metabolic health and glucose metabolism.

How Does This Apply to Leftovers? 

Not only does leftover spaghetti somehow magically taste better the next day, it is also better for you! As it turns out, raw starchy food (like potatoes, rice, or pasta) has a highly ordered molecular structure. This is why it can be challenging for the body to digest foods like raw potatoes. However, when we heat these starches in water, it weakens the structure of the glucose molecules. This allows for the body to pull apart and absorb glucose molecules much easier after we boil our starches. Since the cooked starches are easier to absorb, the glucose gets into our bloodstream faster and spikes blood sugar quickly. This is why cooked, starchy foods like potatoes, spaghetti, and rice all lead to rapid blood sugar spikes.

However, if you are a pasta lover and trying to improve your metabolic health, we are here for you with a solution. When we refrigerate our cooked starches, the cool temperature allows the molecules to reassemble themselves into a resistant starch. Resistant starches are a form of carbohydrate that is not easily broken down by the body (much like a fiber).  The presence of resistant starches is why next day, chilled rice does not spike blood sugar to the same extent as last night’s heated rice.

If you prefer your potatoes heated, we have great news. Recent research has shown that reheating these resistant starches is even better! Researchers are not entirely sure why it works but reheating the leftovers lowers the blood sugar response even more than cooled starches. We need more studies to show the optimal heating, cooling, and reheating time and temperatures, but as soon as more studies are conducted on this topic, we will keep you informed.

Starchy foods that can be turned into resistant starches by cooling and/or reheating include: potatoes, rice, pasta, barley, peas, lentils, and beans. Try cooking dinner ahead of time, sticking it in the freezer, then enjoying your reheated resistant starches throughout the week.

Additional Health Benefits

Beyond blood sugar control, resistant starch offers several other health advantages:

• Enhanced Gut Health: By fermenting in the large intestine, resistant starch feeds beneficial gut bacteria, promoting a healthy microbiome.
• Increased Satiety: Resistant starch contributes to a feeling of fullness, which can aid in weight management by reducing overall calorie intake.
• Digestive Health: It aids in regular bowel movements and may help prevent constipation.

Incorporating Resistant Starch into Your Diet

To harness the benefits of resistant starch, consider the following dietary adjustments:

• Include Naturally Rich Foods: Consume foods high in resistant starch, such as legumes (lentils, beans, chickpeas), oats, and green bananas or plantains.
• Utilize Cooking and Cooling Methods: Prepare starchy foods like potatoes, rice, and pasta, then cool them before consumption (and/or reheat them later). This process increases the resistant starch content.

By understanding and incorporating resistant starch into your diet, you can take proactive steps toward better blood sugar management and overall health.

Author: Dr. Colleen Gulick, Ph.D. (ExPhys), MS (ExPhys), BS (BioE), EIT (ME), CSCS