Written by Hadi Jalali | Published on February 19, 2023 | Last revised on on February 19, 2023

How to Lose Fat with Resistant Starch

Cooked starchy foods (rice, pasta, potatoes, etc.) are quickly digested and can spike blood glucose levels. This makes starch one of the main contributors of weight gain, dysfunctional metabolism, and type 2 diabetes. But retrogradation of starch—slowly cooling down starchy foods after cooking them—significantly reduces the risk of weight gain and its related health problems. Fortunately, the benefits remain even if you reheat the food after cooling, so losing fat with resistant starch doesn’t have to be unpleasant.

📅  How often: as often as you want
⌛  Time required: passive

Benefits

  • Less sluggishness and fatigue (via lower blood glucose levels)
  • Better attention and alertness (via lower blood glucose levels)
  • Better cognitive function (via lower blood glucose levels)
  • Fat loss (via improved insulin sensitivity)
  • Improved gut health (via promoting the growth of beneficial gut bacteria)
  • Reduced risk of colorectal cancer and cardiovascular disease (via all the above)

My take

I have a mental list of foods I like, ordered loosely in terms of nutrition. Sprouts, berries and fermented vegetables are near the top; candy, ice cream and pizza are near the bottom. I suspect that if you’re concerned with nutrition, you probably have such a mental list, too.

Objectively, simple starchy foods like white rice, pasta and potatoes wouldn’t be high on anyone’s list. While cheap and filling, they’re low in micronutrients and, more importantly, can raise blood glucose to levels that cause inflammation and impair cognitive function, even if they don’t affect your weight (yet).

But since I still enjoy eating them occasionally, I try to mitigate their main downside: blood glucose spikes.

I know several methods of lowering blood glucose, and try to always employ one when I eat. This habit is one of them. It needs a bit of planning ahead. But as a reward, you not only prevent a blood glucose spike, but make the starch beneficial to your gut microbiome. This moves simple starches up my list… very slightly.

We’ll explore the rest of these blood-glucose-lowering methods in future newsletters and articles.

The habit: retrogradation of starch

The basic idea here is, fully cool down your starchy foods before you reheat them to eat. Optimizing the result, however, takes a few more steps:

1. Plan ahead.
Cook your starchy food at least a day early.

2. Let it cool down slowly.
Slower cooling increases the amount of starch that re-crystalizes into resistant starch. Ideally, let the starchy food cool down fully at room temperature, then transfer it to the fridge.

3. Don’t add sugars or fat (oil, cream, butter, etc.) while it cools.
In general, adding sugar or fat to a starch-containing food can slow down the rate of retrogradation and reduce the amount of resistant starch that’s created.

4. Keep it intact.
The less processed the starch, the slower it digests, and the lower the rise in blood glucose.
E.g. whole potatoes rather than mashed potatoes.

5. Reheat and enjoy!
Add this point, you can add fat if you like.

Key points

  • Uncooked and unprocessed starches contain high amounts of resistant starch, which is lost in cooking. This habit is to gain back some of them.
  • Slowly cooling down starchy foods after cooking increases their resistant starch content.
  • Resistant starch, similar to fiber, is beneficial to the large intestine and feeds the gut microbiome, which in turn positively affects many aspects of health.
  • Choosing healthier starches (listed in Tips below) will make the result more nutritious.
  • Don’t let this habit become an excuse to eat more simple starches like white rice and pasta. Opt for more nutritious foods instead.

Tips

  • This habit applies to all dietary starch sources. Here are some of them: 🍚 Rice, 🌾 Wheat, 🌽 Corn (maize), 🥔 Potato, 🍌 Banana, 🍠 Sweet potato, 🍠 Cassava, 🍠 Yam, 🥫 Certain beans: black bean, kidney bean, navy bean, pinto bean, mung bean, pea, soybean.
  • Here are some healthier starch sources with a high amylose-to-amylopectin ratio: 🍚 Brown, red or black rice; 🍚 Wild rice (not actually a type of rice, but a seed), 🍲 Quinoa, 🌾 Oat, 🌾 Buckwheat, 🌾 Barley, 🌾 Spelt, 🌾 Millet, 🌾 Rye, 🥫 Lentil, 🥫 Chickpea, 🥫 Lima beans, 🌰 Chestnut (and water chestnut), 🍌 Green banana, 🍠 Arrowroot, 🍠 Taro.
  • To slowly cool down starchy foods, ideally cook them at night, letting them cool at room temperature overnight (unless you live in a hot climate), and refrigerate them in the morning.

Do I need this habit?

One of the main causes of weight gain and the metabolic dysfunction that leads to type 2 diabetes is dietary starch. Starch is a key food staple for many people around the world, and if that includes you, it’s important to try and negate some of its drawbacks.

Consuming starches from raw foods, which have larger, more intact, and less gelatinized particles, or from heated and cooled grains or vegetables with retrograded starches can reduce the risk of type 2 diabetes, and as part of a nutritious and balanced diet, can help you lose fat.

What are the effects?

Eating cooked foods high in starch can spike blood glucose. Cooling them creates some resistant starch (RS) through a process called retrogradation. This reduces the blood glucose spike because RS resists digestion and makes it to the large intestine, where it has beneficial effects.

Lowering blood glucose to stable levels has several important benefits:

  • High levels of blood glucose cause a rise in energy followed by a crash, because the body removes excess glucose from the bloodstream using insulin. This crash can cause fatigue and loss of attention and alertness. Stabilizing blood glucose levels can help you avoid this rise and crash of energy.
  • Brief spikes in blood glucose levels can impair cognitive function by disrupting the regulation of neurotransmitters in the brain, and disabling energy metabolism and cerebral blood flow (blood flow to the brain.)
  • Persistently high levels of blood glucose, over time, is associated with reduced brain volume and gray matter density, and impaired connectivity between brain regions.
  • Avoiding spikes in blood glucose helps improve the body’s sensitivity to insulin, which in turn promotes the uptake of glucose by muscles and the liver. This, in turn, reduces the amount of glucose that’s converted into body fat, and increases the body’s ability to use fat as energy during exercise. Over time, the result is fat loss.

The fermentation of RS by the gut microbiome creates short-chain fatty acids, which are beneficial to the bacteria in the colon as well as the colon itself and the liver, among other tissues. Cumulatively, this is beneficial to gut health, and can reduce the risk of colon cancer. The gut is important for a range of critical functions in the body:

  • Synthesizing nutrients
  • Immunity
  • Cognitive function and mental health
  • Hormonal balance

Short chain fatty acids (produced by the gut microbiome during the fermentation of resistant starch and dietary fiber) can also stimulate the production of hormones that control blood sugar levels, and can reduce inflammation in the body via complex mechanisms (explained in our “What’s the science?” section).

What’s the science?

What’s starch?

Starch is a carbohydrate derived from grains, beans, and some vegetables. It is composed of chains of glucose molecules that can be arranged in straight structures (called amylose) or branched structures (called amylopectin).

In terms of digestion, starches can be split into:

  • Rapidly digestible starch
  • Slowly digestible starch
  • Resistant starch
What happens to starch when it’s cooked and cooled?

Unprocessed starch is fermented or consumed by microorganisms in the large intestine, producing short-chain fatty acids that are utilized as fuel and help these microorganisms maintain and develop.

When starch is cooked, starch granules absorb water and swell, which causes the starch molecules to partially unfold—this is called gelatinization. This changes starch from an insoluble, hard-to-digest granules to quickly digestible glucose chains which can increase blood glucose.

When starch is cooled down after cooking, some of its glucose molecules form hydrogen bonds, and starch chains (that are made up of these glucose molecules) recrystallize, turning into resistant starch and functioning like prebiotic dietary fiber—this recrystallization process is known as the retrogradation of starch.

Why is it best not to add fat or sugar to starchy food while they cool?

In general, adding fat or sugar to a starch-containing food can slow down the rate of retrogradation and reduce the overall amount of resistant starch that’s created. For fat, this effect may be due to the ability of fat to coat starch granules, and prevent water from reaching starch molecules, which slows down the rate of recrystallization. For sugar, it’s thought that sugar can compete with starch molecules for available water, preventing the formation of crystals.

Why are blood glucose spikes bad?

Elevated blood glucose levels lead to elevated insulin. And elevated insulin is one of the key causes of metabolic dysfunction—a group of conditions with abnormalities in the body’s metabolic processes, such as type 2 diabetes, obesity, cardiovascular disease, and metabolic syndrome. Elevated insulin also promotes inflammation, affecting the body systemically, including the brain. Conversely, low insulin levels are positively correlated with good health.

What differentiates healthier starchy foods from unhealthier ones?

Amylose and amylopectin are two types of starch molecules found in many carbohydrate-rich foods. High-amylose starches, found in foods like beans, basmati rice, and green bananas, form very tight structures that slow digestion and are less likely to cause blood glucose spikes. High amylopectin starches, found in foods like white bread, rice, and pastries, are more rapidly absorbed and tend to cause blood glucose spikes.

How do short-chain fatty acids lower inflammation?

Inflammation is the immune system’s natural response to injury or infection. But, chronic inflammation (inflammation that lasts for a long time) can contribute to the development of many diseases. Short-chain fatty acids lower inflammation in the body in several ways:

  • They help maintain the gut barrier, which prevents gut bacteria from leaking into the bloodstream and causing inflammation.
  • They inhibit the production of pro-inflammatory cytokines (proteins secreted by cells of the immune system and other cells).
  • They activate anti-inflammatory pathways such as Nrf2.
  • They help regulate the function of immune cells, such as T cells and macrophages.

Research citations

Evaluation of 25 RCTs involving 369 participants found that postprandial (after eating) blood glucose and insulin levels could be reduced by the addition of high-amylose starch ingredients, when maintaining botanical structures (starch granule, cellular, and tissue structures) by minimizing thermal (cooking) or mechanical processing (mashing, milling, etc.).

Cold storage of boiled potatoes increased resistant starch (RS) content significantly from 3.3 to 5.2% (starch basis). Glycaemic index (GI) and insulinemic index (II) of cold potatoes added with vinegar (GI/II=96/128) were significantly reduced by 43 and 31%, respectively, compared with GI/II of freshly boiled potatoes (168/185). Furthermore, cold storage per se lowered II with 28% compared with the corresponding value for freshly boiled potatoes.

This study found a 26.8% reduction of insulin response for retrograded starch compared with non-retrograded starch:

These reviews and trials discuss the negative effects of elevated glucose and insulin on the brain and body:

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