Carb Blocker 101: What You Need to Know - Perfect Keto

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Carb Blocker 101: What You Need to Know


Carbs have gotten a bad rap in recent years, but not everyone is willing to give them up.


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To address this dilemma, more people are turning to carb blockers. These supplements — marketed as weight loss supplements — are growing in popularity with promises that you can eat all the pasta and bread you want without consequence.

Sounds too good to be true, right? Read on to find out if these supplements are as incredible as they sound.

What Is a Carb Blocker?

Carb blockers do exactly what they sound like… they block your body from digesting carbohydrates.

Also known as starch blockers, carb blockers block the enzymes you need to break down and digest carbohydrates.

See, when you eat complex carbohydrates, your body can’t absorb them unless they’re broken down into simple sugars. And this breakdown happens thanks to the digestive enzyme known as amylase.

Carb blockers are amylase inhibitors.

When you consume these inhibitors, they prevent the enzyme alpha-amylase (in your saliva) from attaching to starches and breaking them down into simple carbs that your body can absorb.

By blocking your saliva’s ability to produce amylase, these complex carbs will make their way through your body without raising your blood sugar or contributing any calories..

While the majority of today’s diet supplements focus on improving your metabolism to more effectively digest calories, carb blockers promote the idea that you can eat large amounts of carbs without having to count them as calories at all.

The Science Behind Carb Blockers

There are two main groups of carbohydrates — complex and simple.

Simple carbohydrates are in processed foods such as candy, soda, milk, and fruits.

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Complex carbohydrates are foods with nutritional value, higher fiber content, and a slower digestion process.

Examples of complex carbohydrates include grains, quinoa, broccoli and beans[*].

When you begin to chew a complex carbohydrate like pasta, grains, or potatoes, your body starts to produce the digestive enzyme alpha-amylase through your salivary glands. This starts the process of converting complex carbs into simple carbs.

Once your body breaks down the carbs into simple carbohydrates, the food will then enter your stomach. This is where carbohydrate blockers come into play.

A chain of simple carbs linked together makes up complex carbs. To absorb complex carbs, your body’s enzymes need to break them down.

After ingestion, carb blockers can help stop the digestive enzymes that break carbs down into small, singular units of sugar also known as simple carbohydrates. These complex carbs will go straight into the large intestine without being broken down into simple carbs.

When this happens, they don’t contribute calories and they don’t spike blood sugar.

That said, starch blockers only help with complex carbs, not simple carbs.

Translation: You can’t eat get away with eating sweet, sugar-filled snacks without consequences — even with carb blockers.

The Most Popular Natural Carb Blocker Ingredient

Most starch blockers are made from a bean derivative — the most common is the white kidney bean extract known as Phaseolus vulgaris[*].

If you search online or at your local supplement store, you’ll notice that almost all carb blockers use white kidney bean extract as the main ingredient. While supplement manufacturers market an array of formulas, white kidney bean extract is the only substance that has evidence and studies to back up its claims[*][*].

White kidney bean extracts work by blocking your body from producing the enzyme needed to digest starches.

Once the white kidney bean extract blocks amylase from breaking down those complex carbs you eat, the food will pass right through your digestive tract without being broken down into simple carbohydrates.

One study examined 60 people in a randomized, double-blind, placebo-controlled setting. The trial found that those who consumed white kidney bean extract lost an extra three pounds of body fat while maintaining lean mass[*].

The recommended amount of white kidney bean extract is 1,500 to 3,000 mg per day. If you’re considering taking this supplement, a typical dose is one to two capsules, each containing 500 mg[*].

In another randomized, double-blind placebo study, the white kidney bean extract supplement effectively blocked carbs, contributing to an average of seven pounds lost, while the placebo group gained three pounds[*].

How Your Body Uses Carbs for Energy

Out of the three macronutrients — proteins, fats, and carbohydrates — your body burns carbs first for energy because glucose is your body’s preferred energy source — especially if you’re not fat-adapted.

When you consume complex carbs, your body breaks them down into glucose, which then makes its way into your blood via your digestive system. Once that glucose hits your bloodstream, your body signals your pancreas to produce insulin. Insulin is a hormone that signals your cells to absorb glucose for energy and regulates the amount of glucose in your blood.


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Once inside your cells, glucose gets turned into energy. Any glucose that your body can’t use for energy gets converted it into glycogen (stored glucose) and stored in your liver and muscles. Whatever can’t be stored gets turned into body fat.

Glycogen only gets released when your blood sugar lowers to a certain level, signaling to your body that you need more energy. When your blood sugar lowers, your liver releases glycogen.

This repeated cycle ensures your body has a consistent energy source.

When you restrict carbs, your body starts looking for other sources of fuel for energy. Eventually, it will start to break down dietary fat and body fat for fuel through a process called beta oxidation.

Ketosis is the metabolic term for what happens when you start running off ketones and fatty acids instead of glucose from carbs.

Downside to Carb Consumption

The goal of carb blockers is to prevent carbs from being absorbed into your body. But what’s so bad about carbohydrates?

When you eat too many calories — particularly in the form of simple carbohydrates — your body reaches its capacity for storing glycogen. The liver will then resort to converting the stored carbs into fat so it can transport the excess energy to your body’s fat cells for long-term storage.

Your fat cells will release this energy whenever it’s needed. And by eating more calories than your body burns, you’ll keep adding more fat to your body.

Carb consumption also directly influences elevated blood sugar levels, especially in the form of simple sugars. Although glucose behaves as a fuel source for cells at normal levels, it can act as a poison when there’s a surplus.

Chronic high sugar levels can cause your pancreas to pump out massive amounts of insulin to keep up with all the glucose in your blood. But your pancreas can only work double time for so long. After a while, chronically high blood sugar and insulin levels lead to damage to the pancreatic cells and most likely — insulin resistance.

A Multi-Faceted Supplement

Even though carb blockers are mostly marketed as a weight-loss aid, several studies have shown there are more benefits to them besides helping you lose a few pounds.

Research suggests that these supplements can also help control blood sugar levels and regulate hormone production.

Blood Sugar Levels

Since carb blockers inhibit the digestion of complex carbohydrates, they also function to lower high blood sugar levels in the body[*].

One study found white bean extract helped reduce the glycemic index of white bread. As a result, white bean extract appeared to help normalize blood sugar levels after eating simple carbohydrates[*].

While carb blockers may work in the short term, you shouldn’t take this supplement long-term.

By following a low-carb, ketogenic diet, you can experience even better results than taking carb blocking supplements. Adopting a keto lifestyle can normalize your blood sugar levels for as long as you decide to stick to the diet.

Regulating Hormones

There’s some evidence that carb blockers can help regulate ghrelin, your body’s hunger hormone. This means it’s possible that white kidney bean extract may reduce food cravings[*].

And since carb blockers help carbs pass to the large intestine undigested, many experts say they act as a resistant starch. Resistant starches are special starches linked with weight loss and better insulin sensitivity[*].

Safety and Side Effects

While carb blockers are generally considered safe to consume, they may still have adverse effects.

The most common side effects include gastrointestinal issues such as bloating, stomach cramps, and diarrhea[*]. When the small intestine doesn’t absorb carbs properly, they travel to the large intestine and become fermented by bacteria.

This isn’t necessarily a bad thing and providing food for your gut bugs can result in better microbial diversity, which equals better gut health overall[*].

But too much fermentation can lead to excess gas and digestive issues, including bacterial overgrowth, aka, SIBO.

Side effects vary depending on the frequency and amount you take. The gastrointestinal discomfort is likely to diminish the more your body adjusts.

When to Avoid These Blockers

As with any dietary supplement, it’s important to see a doctor before adding it to your diet.

If you take insulin or another form of diabetes medication, speak with your physician before taking carb blockers. There are cases where using carb blockers in conjunction with diabetic medication can lower your blood sugar to critical levels.

Proceed With Caution

While people will never stop looking for shortcuts to lose weight, the truth is that there is no magic pill — even if it’s made with natural ingredients.

While carb blockers can help you lose a few extra pounds and curb cravings, it’s not something you should rely on.

Adopting a low-carb, high-fat ketogenic lifestyle is a much safer and dependable weight loss method.

The longer you stick to a low-carb diet, the closer you’ll get to reaching your weight loss goals.


Join 90k+ people who are losing weight with Keto Kickstart, our doctor-developed program designed to give you real weight loss results.


4 thoughts on “Carb Blocker 101: What You Need to Know

  1. What use would they have for “cheat” days? Or days where you didn’t have control over your food (like a conference or catered business meeting)? Would be curious to know.

  2. Could carb blockers be used in conjunction with a ketogenic/low carb diet? Ive been on low carb/keto for years, ive lost 50lbs and I’m very happy with my weight, but id love to get rid of that last stubborn 7-8lbs (im a student who is constantly stressed and lacks time for consistent exercise which i know would easily melt away those last few pounds), im wondering if adding a starch blocker to my keto diet would maybe accelerate the weight loss, even by a tiny bit? What do people think of the possible benefits of using starch neutralizers in conjunction with keto?

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