Resistant starch - does it have a place in a low-carb diet?

When most people hear the word starch, they think “carbs” — and for anyone watching blood sugar or managing metabolic conditions, that often sounds like something to avoid. But not all starches behave the same way in the body. Some starches act more like dietary fibre than carbohydrates. These special types are known as resistant starches, and they have powerful effects on your gut microbiome, metabolic health, and even mitochondrial function.

Resistant starch is now being studied as one of the most accessible, low-cost dietary tools for improving insulin sensitivity, inflammation, and digestive balance — all without sabotaging a low-carb lifestyle.

Here we describe more about resistant starches, and how you might include some RS in your diet even when keeping the carbs low.

What are resistant starches?

Resistant starch (RS) is a form of carbohydrate that resists digestion in the small intestine and behaves like soluble fibre. Rather than being broken down into glucose, resistant starch passes through to the large intestine, where it becomes fuel for beneficial gut bacteria.

Your gut microbes ferment this starch, producing short-chain fatty acids (SCFAs) — especially butyrate, acetate, and propionate. Butyrate, in particular, is crucial for:

• Feeding colon cells (colonocytes), maintaining a healthy gut barrier

• Reducing inflammation throughout the body

• Enhancing mitochondrial energy production and supporting insulin sensitivity

Where do you find Resistant Starch

Resistant starch is found naturally in certain foods, such as:

• Plantains and (unripe)green bananas - the starch in these unripe fruits is resistant to digestion. 

• Beans and legumes - lentils, chickpeas, black beans, and kidney beans are excellent sources 

• Whole grains - oats, barley, brown rice, and quinoa. 

• Nuts and seeds are also good sources of resistant starch. 

Foods may also become high in resistant starch after cooking and cooling:

• Potatoes - cooking potatoes and then chilling them increases their resistant starch content 

• Rice - cold cooked rice is a good source of resistant starch 

• Pasta - similar to rice, cooked and cooled pasta contains resistant starch

• Whole grains - whole grains like oats and barley can see an increase in resistant starch after cooking and chilling 

Photo courtesy of Vimkay, Creative Commons Attribution-Share Alike 4.0 International

Types of Resistant Starch

There are five types of Resistant Starch as shown in the table below:

Five types of Resistant Starch

How Resistant Starch Improves Metabolic Health

1. Improves Insulin Sensitivity and Blood Sugar Control

Unlike digestible starches, RS does not cause sharp glucose spikes. Instead, it can improve insulin response in the long term:

• A 12-week trial of 40g/day of resistant starch (RS2) improved insulin sensitivity by 33% in overweight adults

• A systematic review and meta-analysis of studies in type 2 diabetes, found that supplementation with types 1 and 2 resistant starches lowered post-prandial glucose and fasting glucose, and type 2 RS improved the post-prandial insulin response

• Mechanistically, RS appears to stimulate GLP-1 secretion, a hormone that helps regulate blood sugar and appetite, which is also targeted by weight loss drugs, such as Mounjaro

2. Supports a Healthy Gut Microbiome

Resistant starch selectively fuels butyrate-producing bacteria — such as Faecalibacterium prausnitzii, Roseburia, and Eubacterium rectale. Butyrate:

• Nourishes gut lining cells

• Reduces inflammation and oxidative stress

• Helps maintain tight junctions in the intestinal wall, preventing “leaky gut”

A balanced gut environment influences the immune system and even mitochondrial function, which may explain why resistant starch helps conditions associated with fatigue and inflammation.

3. Reduces Inflammation and Supports Immune Balance

SCFAs produced from RS fermentation regulate inflammatory cytokines and improve intestinal immunity.Higher butyrate levels are associated with lower C-reactive protein (CRP) and TNF-α — markers linked to metabolic and autoimmune conditions.

4. Improves Fullness after Eating and Weight Management

RS increases satiety hormones (GLP-1, PYY) and may decrease ghrelin (the hunger hormone).Participants in clinical trials often reported reduced appetite and smaller portion sizes without consciously restricting calories.

5. Improves Lipid Metabolism

Animal and early human studies suggest resistant starch may reduce serum triglycerides and improve cholesterol ratios by enhancing fat oxidation and reducing hepatic lipogenesis.

How to Increase Resistant Starch on a low carb diet

Think of resistant starch in the context of your fibre intake as it is a type of fermentable fibre that nourishes the bacteria in our colons. Resistant starch appears to produced more healthy butyrate than typical soluble fibre, which is beneficial for gut health. We should aim to include 30g of fibre in our diets every day. Aim to include 5-20g of resistant starch as part of your total fibre intake each day.

Ways to increase resistant starches in your diet:

Eat foods that naturally contain type 2 resistant starch such as unripe bananas, plantains, legumes, oats and peanuts. The resistant starch in these foods reduces with heading, so avoid cooking unless you plan to cool them afterwards.

Heat and cool certain foods - resistant starch will be produced from foods such as rice or potatoes after cooking then cooling these foods.

However, bear in mind that although resistance starch increases after cooking and cooling, they will still contain a lot of other starch, so if you are trying to keep carbs down, you will need to manage your portion size.

For example if you eat 150g of cooked and cooled new potatoes they will contain 25g of total carbs, including 4.5g resistant starch. This means your glycamic response will be 30-50% lower than eating freshly cooked potatoes. However, you will still be consuming 20.5 g of carbs that will affect your blood glucose.

Add supplementary resistant starch to your food

You can add starch already prepared, such a potato starch or green banana flour to your food to add resistant starch to your diet. Using powdered flours of this type can add quite a lot of extra resistant starch to your diet if used regularly without the addition of a lot of extra other carbohydrates. For example raw potato starch provides 8-10g of resistant starch per 100g, with no other carbs. They are also lower carb options than using cooked and cooled starches, which often contain quite a lot of starchy carbohydrate which is not resistant.

Flour made with green bananas or plantains can be sprinkled on food, added to yoghurt, smoothies or even used to make pancakes, although cooking will reduce resistant starch content to some extent.

Green banana flour pancakes recipe from Lovele - recipe here

Warning: if you decide to use powdered starches as they can lead to digestive symptoms if introduced too quickly. Introduce slowly by adding just a teaspoon to your food initially, and gradually increase how much you use over time.

In summary

Resistant starch is a functional carbohydrate that behaves like soluble fibre and is beneficial for gut and general health.

• It supports gut microbes, improves insulin sensitivity, and helps to reduce inflammation in the body

• You can include it in a low-carb diet by using cooled starches, green banana flour, or potato starch. Just remember to use small portion sizes of cooled starches to keep carbs down

• Introduce gradually and aim for 5–20g/day depending on tolerance and goals.

• Think of resistant starch as a bridge between gut health and metabolic resilience