How Do Carb Blockers Work? (Are They Really Effective?)

Dr. Harshi Dhingra, MBBS, MD
Published by Dr. Harshi Dhingra, MBBS, MD | Medical Doctor
Last updated: June 21, 2024
FACT CHECKED by Dr. Kristy Dayanan, BS, MD
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Today, many popular diets minimize the amount of carbs to reduce sugar in the body and promote overall wellness.

However, carbs are also associated with some of our favorite foods, making them tempting to resist.

That’s where carb blockers come in.

These supplements prevent many of the side effects that come with ingesting carbs, allowing you to enjoy your favorite meals without worry or indigestion.

We’ve spent hours delving into what medical research has to say about carb blockers and their effects. Read on to learn more.

Quick Summary

  • Carb blockers aid weight management by preventing the digestion of complex carbohydrates, reducing calorie intake.
  • Studies indicate carb blockers can inhibit up to 65% of carb-digesting enzymes, though the pancreas may compensate by producing more enzymes.
  • One study showed that a strong carb blocker inhibited 97% of enzymes but only prevented 7% of carbs from being absorbed, highlighting their limited but significant impact on weight loss.
  • From my clinical experience, carb blockers can be a useful tool for weight management, especially when combined with a balanced diet and regular exercise.

How Do Carb Blockers Work?

spilled capsules in a bottle

Carb blockers work by stopping the digestion of complex carbs through the inhibition of the enzyme alpha-amylase. These supplements block complex carb digestion, aiding weight loss.

Carbs are either simple (quick-energy sources like fruits and sweets) or complex (slow-digesting, found in grains and legumes). Starch blockers don't affect simple carbs.

They work by inhibiting alpha-amylase, the enzyme that breaks down complex carbs. This prevents these carbs from being absorbed, reducing calorie intake.

Lastly, carb blockers come in two types:

  • white kidney bean extract (made from white kidney beans)
  • alpha-glucosidase inhibitors (AGIs, a form of diabetic medication used in the treatment of type II diabetes)

Carb blockers, either white bean extract or AGIs, work similarly but target different enzymes. It's crucial to remember individual responses vary due to genetics. Generally, this is how they function for most people.

Are They Effective?

female medical person holding a bottle of capsules

They are partially effective - carb blockers can inhibit carb-digesting enzymes, but their effectiveness varies, with studies showing they may only prevent a fraction of carb absorption.

Studies show carb blockers can inhibit up to 65% of carb-digesting enzymes. They block digestive enzymes, but the pancreas compensates by producing more. This means only a fraction of carbs are blocked.

For instance, a study in the American Journal of Gastroenterology found a strong carb blocker inhibited 97% of enzymes but only prevented 7% of carb absorption [1].

Though this seems minor, it's meaningful for weight loss, where every calorie matters.

3 Main Benefits of Taking Carb Blockers

woman holding an apple with a measuring tape around it, man measuring his waist

Carb blockers offer a number of benefits, including helping with weight loss, managing blood sugar, and increasing the body’s resistance to starches.

1. Weight Loss

My observations align with research: carb-blocking supplements often lead to significant weight loss and fat management. They reduce carb absorption, cutting overall calorie intake and aiding weight control.

These blockers also boost satiety hormones and decrease the hunger hormone ghrelin. A study in the Diabetes, Metabolic Syndrome, and Obesity journal showed rats eating less when given carb blockers [2].

By slowing carb digestion, these supplements help maintain a feeling of fullness for longer.

2. Blood Sugar Control

person using glucose level checker

Carb blockers, like white kidney bean extract, significantly impact blood sugar regulation. In my practice, they've helped patients manage blood sugar by reducing carb absorption.

These supplements stabilize blood sugar spikes, even after high-carb meals. A Nutrition Journal study showed improved blood sugar control in diabetic patients after carb consumption [3].

“Blood samples were taken before the intake of the rice and 30, 60, 90, and 120 minutes afterward. Blood sugar levels 30 minutes after eating the rice were significantly lower with the test product. Plasma insulin levels were [also] significantly lower compared to the control at 30 and 60 minutes after consuming the rice.”

- Marilyn L. Barrett, Pharmacognosy Researcher

While beneficial for type II diabetics eating starchy foods, carb blockers are a short-term fix. A long-term, low-carb diet remains the most effective strategy for blood sugar management.

3. Increasing Resistant Starch Levels

shirtless man holding his abs smiling

Resistant starches are a type of starch that is not digested and often finds its way into the large intestine undigested.

They are fermented by gut bacteria and create short-chain fatty acids and important gases.

As higher starch levels have been associated with decreased body fat, healthier gut bacteria, and increased insulin sensitivity, carb blockers may also assist in carb digestion and wellness.

Side Effects

close up image of a person holding his stomachache

Common side effects of carb blockers include bloating, low blood sugar, stomach cramps, diarrhea, and gas. These occur due to changes in starch digestion and gut bacteria in the large intestine struggling to ferment increased resistant starch, leading to gas production.

To minimize discomfort, start with a low dose and gradually increase it. These side effects typically diminish as the body adapts and the undigested carbs are expelled.

Note that carb blockers aren't as tightly regulated as other supplements. Ensure you choose a reputable manufacturer if using them for weight loss.

3 Natural Alternatives to Carb Blockers

woman thinking while holding a capsule bottle

Carb blockers can help manage carbs, but they're supplements, not lifestyle replacements. Long-term weight management and health rely on a balanced diet and regular exercise.

Here are some natural alternatives to carb blockers I often recommend to my patients.

  • Limit your intake of simple carbs: Simple carbs, found in processed foods, soft drinks, and snacks, are quickly absorbed into the bloodstream. Reducing these can help lower calorie intake and support fitness goals.
  • Ketogenic diet: This diet triggers ketosis, where the body uses fat for energy. It typically includes 65-90% fats, 20-30% proteins, and less than 5% carbs. Adopting a keto lifestyle can improve blood sugar control and aid in fat reduction.
  • Paleo diet: Also known as the Caveman Diet, this approach focuses on unprocessed, natural foods similar to those our ancestors ate. It cuts out processed foods and carb-rich grains, promoting a diet rich in fish, eggs, fruits, vegetables, nuts, and seeds. This can help avoid issues linked to high carb consumption.


Are Carb Blockers Safe?

Carb blockers are generally very safe with minimal side effects such as mild stomach upsets.

Users may experience slight discomfort in their gastrointestinal tract, which disappears over time as the body gets used to it.

Who Should Not Take Carb Blockers?

People who should not take carb blockers include pregnant women, diabetic patients under insulin treatment, and individuals who suffer from gastrointestinal disorders.

These groups should avoid carb blockers or consult a doctor before taking these supplements.

How Often Should I Take Carb Blockers?

It is advisable to take them alongside every meal to experience the full potential of carb blockers.

Additionally, you’ll want to give your body an 8 hour time window between doses to allow ample time for proper digestion.


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About The Author

Dr. Harshi Dhingra, MBBS, MD is a published peer-reviewed author and renowned physician from India with over a decade of experience. With her MBBS from Bharati Vidyapeeth and an MD from Rajiv Gandhi University, she actively ensures the accuracy of online dietary supplement and medical information by reviewing and fact-checking health publications.
Learn more about our editorial policy
Dr. Kristy June Dayanan, BS, MD is an author with a BS degree from University of the Philippines and an MD from University of Perpetual Help System. Her ability to simplify medical science complexities and dietary supplement jargon for the average reader makes her a valued medical fact checker and reviewer.
Learn more about our editorial policy

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