Additional menu

Ranking the best carb blockers of 2021

Written by John Davis

Last updated: July 25, 2022

A carb blocker is a supplement that slows down or prevents the absorption of carbohydrates into your body.

Given the rising tide of evidence suggesting that carbohydrates have a particularly harmful effect when it comes to weight gain and the metabolic problems that come along with it, carb blockers are becoming increasingly popular among people looking to shed pounds or fend off weight gain.

Confused about your options? We’ve had our research team investigate and rank the ten best carbohydrate blocking supplements on the market.

Read on to see our rankings and for more details on how these supplements can help you lose weight.


1. Arazo Nutrition White Kidney Bean Carb Blocker

Check price at Amazon

Among the multitude of brands that use white kidney bean extract as the main or only ingredient in their carb blocking supplements, Arazo Nutrition’s supplement stands out due to its high dose and simple, pure supplement design.

If you are looking to keep things minimal, this is a great choice: you get 600 mg of white kidney bean extract per vegan-friendly cellulose capsule, with a minimum of extra ingredients.

2. Irwin Naturals 3-in-1 Carb Blocker

Check price at Amazon

Irwin Naturals 3-in-1 Carb Blocker takes what you might call a “maximalist” approach to blocking carbohydrate absorption.

This supplement uses a range of active ingredients to block the absorption of carbohydrates. These range from familiar ingredients like white kidney bean extract and chromium to more unusual ingredients, like cinnamon extract, flaxseed oil, and the enzymes lipase and protease, which help break down fats and protein.

It’s also got the proprietary black pepper extract BioPerine, which should assist with improving the absorption of many of the active ingredients. If other carb blockers aren’t doing the trick for you, give Irwin Naturals a try.

3. Code Age Keto Carb Blocker

Check price at Amazon

Code Age Keto Carb Blocker uses a three-pronged approach to reduce carbohydrate absorption. The first is by using white kidney bean extract, which is a common and effective strategy among carb blockers.

Next up is cinnamon extract and green tea extract, which both might have beneficial metabolic effects when it comes to weight loss, but whether or not they have an effect on carbohydrate absorption specifically is unclear.

While Code Age Keto Carb Blocker may be an effective way to reduce carbohydrate absorption, it’s not going to totally block carbohydrates, so if you are trying to stay in ketosis, you still can’t go crazy with carbs.

4. BioGanix Pure White Kidney Bean Extract

Check price at Amazon

BioGanix Pure White Kidney Bean Extract uses the same 600 mg dosage of white kidney bean extract that you’ll find in many other carb blockers, though its supplement design is quite pure—there are zero additional ingredients, other than the vegetarian-friendly cellulose capsule used to deliver the supplement.

Because of the large number of capsules per bottle, it’s a good choice if you want to incorporate carb blockers into your diet on a regular basis instead of as an occasional “cheat meal” solution.

5. Phytoral White Kidney Bean

Check price at Amazon

White kidney bean extract is one of the most popular carb blockers due to its ability to shut down carbohydrate absorption.

Phytoral makes one of the most popular white kidney bean supplements, thanks to its fairly high dose (600 mg per capsule) and fairly straightforward supplement design.

If you are looking for a fairly simple way to block carbs, this is a solid choice.

6. Satoomi White Kidney Bean 

Check price at Amazon

Satoomi makes a potent multi-ingredient carb blocker. While it’s based around white kidney bean extract, it also includes a broad range of weight loss supplements, including garcinia cambogia, olive leaf extract, green coffee bean extract, and green tea extract.

This supplement fits in on the more complex and sophisticated end of the spectrum, so while it’s not as strong of a choice for people who just want a carb blocker, it’s a solid pick if you’re looking for a more comprehensive supplement that combines weight loss ingredients with carb blocking ingredients. 

7. Nature’s Craft White Kidney Bean Pro Enzymes

Check price at Amazon

Nature’s Craft White Kidney Bean Pro Enzymes is a pretty typical carb blocking supplement: it delivers 600 mg of white kidney bean extract per capsule, with a reasonably clean supplement design.

However, without much to set it apart from the rest of the competitors with similar products, it’s hard to rank this supplement any higher.

8. Natrol Carb Intercept

Check price at Amazon

Natrol Carb Intercept uses a combination of white kidney bean extract, chromium, and dibasic calcium phosphate to block the absorption of starches.

It’s an innovative product, as most white kidney bean supplements are presented without any additional active compounds.

However, the efficacy is hampered somewhat by a lot of additives in the supplement, and the fact that it contains both milk and soy ingredients, which will turn off some users.

9. Diabetes Doctor Carb & Sugar Blocker

Check price at Amazon

If more traditional carb blockers based on white kidney bean aren’t cutting it for you, it might be worth giving Carb & Sugar Blocker from Diabetes Doctor a try. It uses less common ingredients like chromium, berberine, and gymnemic acid to slow or block the absorption of carbohydrates at meal time.

While it doesn’t have the same proven ingredients as some of the competition, it’s good to have alternatives if the first-line carb blockers don’t work for you.

10. Slimgenics Alpha Slim

Check price at Amazon

Slimgenics Alpha Slim claims to block up to 300 calories per meal, backing this up with a long list of active ingredients.

These range from vitamins A, C, and E to a proprietary blend of white kidney bean, gymnema leaf, ginseng, ginkgo, and other ingredients.

Unfortunately, it’s not possible to evaluate the efficacy of these compounds given that the exact dosage is shrouded in secrecy.

Slimgenics Alpha Slim may have a niche use, but most people would be better off with a different option.

Category winners

Best carb blocker overall: Arazo Nutrition White Kidney Bean Carb Blocker

Arazo Nutrition is our top overall pick thanks to its high dose and heavy reliance on white kidney bean extract, a proven compound for slowing the rate of carbohydrate absorption. Its simple and effective formulation make it an excellent all-around choice.

Best carb blocker for weight loss: Irwin Naturals 3-in-1 Carb Blocker

Irwin Naturals uses a comprehensive approach to bolster weight loss on several fronts—white kidney bean and cinnamon fight carb absorption, lipase and protease aid in fat and protein digestion, and bioperine enhances bioavailability. This approach makes it great for weight loss applications.

Best carb blocker for women: Arazo Nutrition White Kidney Bean Carb Blocker

Arazo Nutrition is great for women who just want a simple and effective carb blocker without any other ingredients. Its dosage is effective and its formulation is pure, making it a good choice for women looking for the best carb blocker.

Best carb blocker for keto diet: Code Age Keto Carb Blocker

Code Age Keto is our recommendation for low-carb and keto dieters because it combines the anti-carb effects of white kidney bean extract with the fat oxidation boosters in cinnamon extract and especially green tea extract. By blocking carb absorption and ramping up fat oxidation, you’ll get even more out of the keto diet.

Best carb blocker for blood sugar control: Arazo Nutrition White Kidney Bean Carb Blocker

Looking to take advantage of improvements in insulin regulation and metabolic control that come along with better-regulated carbohydrate intake? Arazo Nutrition is our pick, thanks to its laser-focus on blocking carbohydrate absorption and its lack of other ingredients that might have off-target effects.

Best carb blocker for cutting: Code Age Keto Carb Blocker

For athletes looking to cut fat quickly, Code Age Keto is a great choice. The fat burning and appetite suppressing properties of the included green tea extract combine well with the carbohydrate blocking action of the white kidney bean extract.

Who should buy carb blockers?

Carb blockers are great for individuals who want to reduce the negative effects of carbs without avoiding them. They are also great for people who are looking to control and manage blood sugar levels.

There is not enough research on the use of carb blockers in special populations such as children and pregnant women, so it’s recommended that they avoid them unless otherwise directed by a medical professional. 

How we ranked

Slimgenics Alpha Slim uses a proprietary formula, hiding the exact doses of the ingredients it uses. Furthermore, some of the ingredients it uses are not proven carb blockers, which is why we ranked it last. Natrol Carb Intercept is a better carb blocker but uses a ton of unnecessary additives and allergens, which is why it ranked near the bottom. 

Sheer Strength’s carb blocker provides a low dose of white kidney bean combined with other potential weight loss agents, including green tea catechins. While a solid option, it’s low dose of white kidney bean ranks it near the bottom for us.

Code Age Keto Carb Blocker uses three different ingredients for maximum effectiveness, which helped it land higher up in our rankings. BioGanix’s carb blocker provides 600 mg of pure white kidney bean extract with zero additives and fillers, bolstering its position as well.

Irwin Naturals carb blocker took 2nd spot for proving a monster of a carb blocking supplement, including powerful ingredients such as white kidney bean extract, chromium and cinnamon extract at clinically effective dosages.

It also includes enzymes to help break down fat and protein, which helps smooth out digestion.

It increases bioavailability by including black pepper extract and is defiantly worth a try. Arazo Nutrition’s carb blocker uses just one ingredient to keep things pure: 600 mg of white kidney bean extract. With no fillers, additives, or cutting agents, it’s easy to see why this product took the top spot. 


Carb blockers might be able to reduce the negative effects of excessive carbohydrate intake. One increasingly prominent scientific theory related to weight gain is the “carbohydrate insulin model” of obesity, which focuses on going beyond the idea of weight maintenance being a matter of calories in versus calories out.

A 2018 scientific article in the Journal of the American Medical Association Internal Medicine by researchers at Boston Children’s Hospital outlines the evidence behind this hypothesis and the implications of it (1).

Under this theory, the primary driver of obesity and weight gain is the consumption of large amounts of carbohydrates, especially sugars and refined carbohydrates.

These carbohydrates have a low glycemic index, meaning they create a sharp rise in blood sugar levels. In response, the body pumps out insulin, a hormone which controls blood sugar.

As a result of rising insulin levels, the blood sugar circulating in the blood gets pulled into fat cells where it is stored as new fat, and finally, blood sugar levels crash.

This process takes several hours after a carbohydrate-rich meal, and explains a number of phenomena, such as the “carb crash” that many people experience in the hours following a meal with a lot of carbohydrates.

Under this theory, hunger and overeating are actually symptoms, not causes, of obesity: the crash in blood sugar drives you to consume more food, and if that next meal is rich in carbs, the cycle starts all over again.

If a carbohydrate blocking supplement could interrupt this process by slowing down or blocking the absorption of carbs, there is firm grounding that it could be quite beneficial for weight loss and weight loss maintenance.

Carb blockers that include white kidney bean can directly inhibit the absorption of carbohydrates. One of the most popular ingredients in carb blockers and other weight loss pills is white kidney bean extract, thanks to some very solid science on its biochemical properties inside your body.

White kidney beans contain a compound that blocks a specific enzyme that helps your body process the carbohydrates in your stomach, leading to decreased absorption of carbs for a given meal.

A study published in the British Journal of Nutrition by a team of researchers in Spain demonstrated the precise mechanism of action (2).

Their study gave rats a dose of either white kidney bean extract or a placebo, both in conjunction with a standardized starch meal.

The researchers were able to demonstrate that the white kidney bean resulted in lower blood sugar levels and even a reduction in food intake.

The rats given the white kidney bean extract may have been less inclined to continue eating because of the increased amount of carbohydrates that remained in their stomach (as they were not absorbed), which suggests that white kidney bean could have a synergistic effect: less caloric absorption, as well as less caloric intake.

Carb blockers with cinnamon might reduce the negative metabolic effects of carbohydrate-rich meals. Cinnamon is rich in biologically active compounds, some of which look like they have beneficial effects on carbohydrate metabolism.

A study published in the journal Hormone and Metabolic Research by researchers at Nagoya University in Japan analyzed the effects of these compounds on insulin resistance, one of the biggest negative metabolic effects of a carb-rich diet (3).

Their study used mice to demonstrate that mice fed a high-sugar diet supplemented with cinnamon extract did not experience the same metabolic deficits as mice not given a cinnamon extract. More specifically, the insulin resistance of the rats fed cinnamon was not nearly as bad.

While cinnamon may not directly block the absorption of carbohydrates, it does look like it could help your body cope with a “cheat meal” more effectively.

As such, including cinnamon extract in a carb blocker could make it more effective, especially for occasional use.

Side effects

Though many carb blockers use slightly different ingredients, the scientific research behind the most common ingredients like white kidney bean extract and cinnamon suggest that they are quite safe.

White kidney bean extract has been screened for toxicity in multiple studies of rats at fairly high doses, with no apparent ill effects (4, 5).

Additionally, clinical trials in humans that have examined commercial preparations including white kidney bean extract, such as one published in 2011 in the Nutrition Journal, have reported no adverse side effects (6).

As for cinnamon extract, early clinical reports indicate that it is well-tolerated and generates minimal side effects (7).

Recommended dose

For carb blocker supplements that contain white kidney bean extract, there is a considerable body of research that has evaluated various doses of white kidney bean extract.

Anything between 500 and 3000 mg per day appears to be effective, though as is usually the case, it’s better to start on the low end first (8).

Cinnamon has mostly been studied at doses ranging from 40 to 80 mg per day (9), though it’s less clear if this is the optimal range for weight loss and weight maintenance.


What is the main goal of carb blockers? Carb blockers are supplements that are used to blunt the negative effects of carbohydrates in your diet. There are a number of ingredients that carb blockers might use to achieve this effect, but the goal is the same: eliminate or slow down the absorption of carbohydrates in your diet so your body doesn’t have to deal with a surge in blood sugar and the negative after-effects.

What is the percentage of carbs that carb blockers block? Despite popular belief, carb blockers only block around 50% of the enzymes responsible for digestion. In one study, it was found that carb blockers ended up blocking less than 10% of the carbs from being absorbed (9).

What are carb blockers? Carb blockers are popular dietary supplements designed to prevent or slow down the digestion of complex carbohydrates. Though they’re often described as “weight loss pills,” there’s very little evidence to support that claim. Carb blockers are popular because they don’t require you to change your diet, allowing you to eat the same amount of carbs as usual without experiencing the same spike in blood sugar levels. They do this by inhibiting the digestive enzymes from breaking down complex carbs, which allows them to pass through your digestive tract quickly without absorbing them into your bloodstream.  

Can carb blockers decrease appetite? Yes, carb blockers can help decrease appetite by slowing down stomach emptying and affecting some of the hormones involved in satiety. A rat study showed that carb blockers help decrease food consumption by up to 90% for a few days (10).

What are the best natural carb blockers? A natural carb blocker is any natural ingredient that inhibits complex carbs from being absorbed into your bloodstream. The most popular all-natural carb blocker supplement is made from a white kidney bean extract. Compared to other carb blockers on the market, it has a higher success rate in terms of weight loss.

How do carbs function in the body? Carbohydrates are one of the most essential macronutrients that your body consumes since they are a primary energy source. When you consume carbohydrates, your body converts them into glucose, which helps produce the energy you need to perform daily tasks. Carb blockers can aid in reducing the calories associated with carbs. It’s best to take carb blockers in moderation, or as directed by a physician, paying close attention to how your body responds.

How do carb blocker supplements work? Carb blockers work by inhibiting the enzymes that target and break down the complex carbs you consume. By inhibiting the release of these enzymes, the carbs are pushed through the digestive tract without breaking down, and therefore are not absorbing into your bloodstream. This results in fewer calories absorbed, and more importantly, your blood sugar and insulin remain unaffected.

Can carb blockers cause you to eat more? In general, carb blockers will not cause you to eat more while you are using them. However, there have been animal studies that show that after carb blockers were stopped, rats ate up to 50% more than before being given carb blockers (11).

How effective are carb blockers? Carb blockers do work, just not in the way that they’re usually advertised. They are not very productive diet pills and very rarely lead to any significant weight loss. However, carb blockers have been proven to positively impact blood insulin levels and blood pressure. At least one study has noted carb blockers improved insulin resistance and helped to lower blood pressure (12).

How do carb blockers help with weight loss? Carb blockers work by blocking most of the enzymes associated with complex carbohydrate digestion. This forces the undigested carbs through the digestive track with minimal calorie absorption. As a result, fewer calories get absorbed, which decreases your overall caloric intake, possibly leading to weight loss. 

Are carb blockers the same as diet pills? Carb blockers are often labeled as diet pills because many companies claim that their products can help boost weight loss and reduce caloric consumption. However, carb blockers work much differently than the typical diet pill. Most diet pills are associated with burning excess fat within the body via appetite suppression and increased energy expenditure. Carb blockers, however, purely prevent the absorption of carbs within your diet. 

Do carb blockers benefit the gut microbiome? Carb blockers can provide the large intestine with resistant starches, which is healthy for gut bacteria to feed on. Studies show that these resistant starches help improve insulin sensitivity, lower body fat, and improve healthy bacteria (13).

Do carb blockers help with weight loss? Carb blockers can aid in weight loss, but there aren’t enough human studies to confirm their efficacy. In a study where participants supplemented their diet with natural white bean extract, subjects lost weight and had a smaller waist size by the end of the study (14).

Can diabetics take a carb blocker? Many diabetics turn to carb blockers out of concern for raising their blood sugar levels when consuming high-glycemic foods (15). 

Do carb blockers cause GI issues? Carb blockers may cause GI issues such as diarrhea, stomach pain, flatulence, and bloating after taking carb blockers, especially in larger amounts.

Do carb blockers lower blood pressure? Carb blockers have been proven to positively impact blood insulin levels and blood pressure. At least one study has noted carb blockers improved insulin resistance and helped to lower blood pressure (16). 

Do carb blockers block calories from being absorbed? Yes, carb blockers can block calories from being absorbed, but only calories that come from carbohydrates – not fat or protein. If you’re still consuming a large number of calories through protein and fat, you won’t see much of a difference in calorie loss. The blocked calories are a direct result of the speed at which the carbs travel through your digestive system. When you take carb blockers, that speed is much faster, which prevents the breakdown and absorption of those carbs. 

Do carb blockers support fat loss? Carb blockers will not do much to improve fat loss since they only restrict the calories that come from complex carbs. While they may provide complementary support for a healthy diet, they’re not the answer you’re looking for in terms of fat loss, especially if you consume a lot of fat calories. 

Does cinnamon work well as a carb blocker? Yes, cinnamon might reduce the negative metabolic effects of carbohydrate-rich meals by acting as a post-carb-effect diminisher. One animal study showed that mice given cinnamon extract didn’t block carbs, but help the body manage the onslaught of carbs during a cheat meal (17). 

Can carb blockers cause low blood sugar? Carb blockers can help lower your blood sugar levels but aren’t usually severe enough to cause any negative health consequences – which makes carb blockers relatively safe for those with diabetes. 

When you consume complex carbohydrates with a high glycemic index, your insulin levels will undoubtedly spike. This is what makes these foods so dangerous for diabetics. With carb blockers, your body won’t digest these complex carbohydrates, which prevents your insulin levels from rising. 

If you already have low blood sugar levels, it may be dangerous to take carb blockers unless directed by a physician. You should speak with your doctor before adding carb blockers to your daily regimen. 

Are carb blockers recommended to keep you in ketosis? Many companies claim that carb blockers can help keep you in ketosis, but there’s not enough research to support those claims.

Despite that, carb blockers can be helpful if you’re on the ketogenic diet. When you’re on a ketogenic diet, you’re looking to reduce your intake of carbohydrates and increase your intake of fats and proteins.

Carb blockers will allow you to “cheat” on your keto diet by blocking the absorption of complex carbs without interfering with the ketosis.

Do carb blockers help prevent the negative effects of a high-carb meal? Yes, carb blockers can reduce the negative effects of excessive carbohydrate intake, such as obeisty, insulin resistance, and metabolic syndrome. They can also help control rebound hunger, which is often caused by a swing in blood sugar levels due to a high carbohydrate consumption.

Does white kidney bean work well as a carb blocker? Yes, white kidney bean extract has been shown to work very well as a carb blocker.

A 2007 study showed that rats given white kidney bean extracts had lower blood sugar levels and reduced appetite because of the increased amount of carbohydrates that remained in their stomach – which didn’t get absorbed (18). 

Related articles


A carb blocker might be an effective way to protect yourself from some of the negative effects of high carbohydrate intake.

Slowing the rate of carbohydrate intake looks like a good bet when it comes to blunting the negative metabolic effects of high carb intake, like the blood sugar spikes.

Carb blockers that use white kidney bean extract seem particularly effective, as the active ingredient in this supplement interferes with your body’s ability to process carbs in your stomach, leading to a slower rise and lower peak in blood sugar after a carb rich meal.

Cinnamon extract seems to be a useful extra ingredient, as it can help protect you from some of the negative metabolic effects of high carb intake, even if your body is still absorbing the same amount of carbs.

While there’s no replacement for actually reducing your dietary intake of carbohydrates, a carb blocker can come in handy on cheat days or on occasions where you don’t have much of a choice but a carb-heavy meal.

For BodyNutrition’s #1 carb blocker recommendation, click here.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.