Resistant Starch

Ever heard someone tell you to eat your potato cold because its better for weight loss?

Is it true?

If so, why… how does that work?

Let’s take a look 👀

Potato is a ‘starchy carb’. Starches are made up of long chains of glucose. Glucose is a simple sugar and is the most abundant monosaccharide, a subcategory of carbs.

FUN FACT: Glucose has the molecular formula C₆H₁₂O₆ This is why you may see 'carbs' written as 'CHO' as a shorthand.

Bored yet? 😴

Wait up, I promise it'll all tie together in a sec.

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Depending on the temperature that we eat starchy foods, like grains, potatoes, beans, corn and plenty more, will change some of the starch type from regular ol 'girl next door' starch (digestible starch) to 'resistant starch'.

There are 4 classifications of resistant starch and it looks like this:

  • Type 1: Is found in grains, seeds and legumes and resists digestion because it’s bound within the fibrous cell walls.

  • Type 2: Is found in some starchy foods, including raw potatoes and green (unripe) bananas.

  • Type 3: Is formes when certain starchy foods, including potatoes and rice, are cooked and then cooled. The cooling turns some of the digestible starches into resistant starches via retrogradation.

  • Type 4: Is man-made and formed via a chemical process.

*However, just like ‘body type’ classifications, several different types of resistant starch can co-exist.

As you can see, cooked potato, then cooled is a ‘type 3’ and the cooling of the food is what turns some of the digestible starches into resistant starches via something we call 'retrogradation'. This is a reaction that takes place when the amylose and amylopectin chains in cooked, gelatinized starch realign themselves as the cooked starch cools.

Normal starches are broken down and absorbed as you would expect, affecting blood glucose post consumption (not a bad thing) but resistant starch is resistant to digestion, so it passes through the intestines without being broken down by your body (again, not a bad thing). The bacteria in your large intestine can feed on this and produce gasses and short-chain fatty acids (like butyrate), which can benefit the health of your cells.

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Butyrate is the preferred fuel of the cells that line your colon, and this therapeutic effect on the colon may aid various digestive disorders under the banner of inflammatory bowel diseases like ulcerative colitis and Crohn's disease, constipation, diverticulitis and diarrhea. The short-chain fatty acids that aren't used by the cells in your colon travel to your bloodstream, liver and the rest of your body, where they may have various beneficial effects.

Back to the questions of ‘is eating your potatoes cold better for weight loss’.

Well, we now know where this claim is coming from and how eating a cold potato is different from hot potato. But then we need to consider HOW WEIGHT LOSS WORKS.

The complex and evolving body is far more complicated than a simple equation that is caloires in vs calories out, BUT the fundamental component of weight loss is eating a calorie controlled diet. Without this, *outside of serious illness* weight loss cannot occur.

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To answer the cold potato question, eating potato cold means you’re consuming some ‘resistant starch’ vs ‘digestible starch’ which means the available calories to be stored or used as potential energy are reduced.

So… less caloires = weight loss right?

Yes BUT these caloires need to be in a significant deficit to TDEE so if eating potatoes cold is the only adjustment you’ve made, this will not change the available consumed caloires by much, so caloires no significant change to weight will be realised.


In summary, eating potatoes cold can be part of a broader weight loss strategy of a calorie controlled diet, but doing this in isolation is a meaningless activity.

Diet Smart. Not Hard

Coach Lizzy