What is Starch and Why Is It Bad for Weight Loss?

Low carbohydrate diets are a popular mode for weight loss.  It is true that cutting out excess sugar, sweetened beverages, sweets, refined grains and packaged snacks that are high in carbohydrates is important for both weight loss and overall health.

On the other hand, some weight loss diets take out all or most sources of carbohydrates including nutrient rich fruits, vegetables, legumes and whole grains.

All sources of carbohydrates are often lumped together in how they affect the body when in reality foods that have carbohydrates can vary in how they impact the body.

For example, naturally high fiber, high nutrient dense carbohydrate foods are often considered complex carbohydrates.

The carbohydrate molecules are large and branched and are not broken down as quickly because the fiber slows the rate of absorption.

Sugar, white flour and other refined grains are examples of simple carbohydrates.  These molecules can be broken down quickly and can raise blood sugar levels rapidly.

Cutting down on simple carbohydrates can be beneficial for weight loss.  However, cutting out sources of complex carbohydrates, also considered starch, is not always associated with benefit for overall health or weight loss.

In fact, some research suggests eating sources of resistant starch may actually be beneficial for weight loss.

What is starch and why it gets a bad rap?

Simple carbohydrates are easy for the body to break down and are considered quick energy sources.

For example, consuming something like white bread or candy will quickly cause a rise in blood sugar.  A rise in blood sugar causes a rise in release of insulin.

Insulin is needed to bring the sugar (energy) from the blood and into the cells of the body for energy or storage.  When there is a strong rise in blood sugar, there is a strong rise in insulin.

Constantly causing these strong surges in glucose and insulin may increase risk for weight gain, type 2 diabetes and promote fat storage.

This is primarily why carbs get a bad rap for weight loss.  Cutting out simple carbohydrates and excess sugar from the diet is recommended for weight loss.

However, complex carbohydrates are broken down differently.  They get absorbed more slowly into the bloodstream and don’t cause a spike in blood sugar and insulin.

Complex carbohydrate sources also provide good sources of fiber, antioxidants, vitamins and minerals.

What is resistant starch?

Resistant starches are called as such because they actually resist digestion.  Normally, carbohydrates are broken down into single and double units that can travel across the small intestine wall.

Then these molecules are in the blood stream and can be used for energy.  Complex carbohydrates that have many branches take longer to get broken down for absorption, but simple carbohydrates may need no to little breakdown for absorption.

Resistant starches actually resist getting broken down and absorbed across the small intestine wall.  The resistant starches then travel to the large intestine.

In the large intestine, the resistant starches act as fuel for bacteria in the colon.  The colon bacteria produce short chain fatty acids which the body uses as energy.

Resistant starches can act as fuel for healthy bacteria (probiotics) which can provide benefits for immune function, digestive health and possibly many more benefits.

According to a 2017 Consumer’s Reports article (1) there are five types of resistance starches.  Resistant starches can be found whole grains, seeds, legumes and under ripe bananas.

Foods that are often shunned by dieters like potatoes, pasta and rice can also be a source of resistant starches.

The trick to getting to most resistant starch out of these foods is to cook them and cool them down: i.e. eating leftovers.

The cooling process after cooking alters the chemical structure in a way that favors resistant starches.

Health benefits associated with resistant starch

A 2015 study (2) concluded the combined consumption of resistant starch and protein can increase fat oxidation and feelings of satiety.

Another 2015 study (3) with 60 women with type 2 diabetes found resistant starch had positive effects on inflammation, lowering HbA1c, blood triglycerides and increasing beneficial HDL cholesterol.

More studies are needed with resistant starch and type 2 diabetes treatments, but this study suggests consuming resistant starch may have a positive effect on health.

Diets that are high in resistant starches like Asian diets are associated with lower risks for obesity and chronic diseases.

Traditional Asian diets are high in rice, vegetables, fruit, low in red meats, processed foods and sugar.  The combination of this diet style is thought to provide many health benefits.

Resistant starches are part of this diet, but not the only component.  Eating foods that are high in resistant starches can be healthy, but they should be a part of a diet that is high in other nutrient dense foods and an active lifestyle.

A 2014 study (4) compared the metabolic responses in East Asian Americans and Caucasian Americans when transitioning from a traditional Asian diet to a traditional Western diet.

Researchers found a traditional Asian diet provided weight loss and improved insulin sensitivity while the Western style diet worsened insulin sensitivity and increased risk for weight gain.

Healthy ways to incorporate resistant starch in your diet

How can you get more resistant starch foods in your diet?

Eat more whole grains like barley, legumes, under ripe bananas and potatoes.

Cooked and cooled pasta and potatoes can also be a source of resistant starches (cold pasta and potato salads).

Does this mean you can eat as much of these foods as you want?  Of course not.  However, these foods can be part of a healthy, balanced diet conducive for weight loss.

If you need some suggestions for incorporating healthy recipes with resistant starch, Eating Well has recipes (5) that are specific for providing resistant starch.

You don’t need to fear foods that are sources of resistant starch if you are trying to lose weight.

Research suggests they can be beneficial.  If you have type 2 diabetes, speak with your doctor before increasing your intake of foods with resistant starches.

More research is needed on the effects of resistant starches and type 2 diabetes.