What Are Carb Blockers - Swolverine

People often think that there is a pill, supplement, or diet that will help them eat their way through the doughnut shop and still have an incredible physique. It’s easy to think that way when you hear the magic words “carb blocker” roll off your tongue in excitement and awe. Unfortunately, carb blockers are no exception to the rule, that only diet and exercise are the tried and true ways to drop the unwanted pounds you so desperately want to lose. Let’s talk about the truth behind carb blockers and what they’re all about before you smash that pack of Oreo’s in hopes of blocking all those carbs.

The Science Behind Carb Blockers 

As the name aptly suggests, carb blockers do exactly what their name intends them to do – they block your body from digesting carbs. But to understand exactly how carb blockers work it helps to understand how carbohydrates work.

Carbs come in two different forms, simple and complex.

Simple carbs are a small unassuming chain of sugar molecules, that are found in processed foods such as cereal, baked goods, desserts, soda, and candy. Most simple carbohydrates are found in the form of sugar additives. Next time you snag any type of packaged good, take a look at the ‘ingredients list’ below the nutrition panel. Simple carbs go by a myriad of aliases, such as corn syrup, high fructose corn syrup, raw sugar, brown sugar, dextrose, fructose, galactose, glucose, granular fruit grape juice concentrate, maltodextrin, lactose, sucrose, molasses, organic cane sugar, sorghum, and turbinado just to name a few.

Your body rapidly absorbs simple carbs, which spikes blood glucose and secretes insulin. Insulin’s job is to dispel the excess glucose from your bloodstream and store it as body fat for energy. Rapid absorption is why you experience the infamous ‘sugar high’, giving you a quick burst of energy, followed by ‘the crash.’ You’re probably heard foods referred to as being ‘high on the GI scale” meaning simple carbohydrates since they spike blood glucose.   

Complex carbohydrates are found in foods such as starchy vegetables, legumes, whole grains, and higher fiber foods. Examples of complex carbohydrates are quinoa, sweet potatoes, yams, oats, brown rice, and whole-wheat pasta. Composed of longer-chained sugar molecules complex carbs are slowly digested, resulting in a longer release of energy. Complex carbs pass through the digestive tract releasing steady amounts of glucose, without spiking blood sugar, resulting in improved satiation. This is why complex carbs are the preferred type of carbohydrates amongst bodybuilders and individuals trying to lose weight.

RELATED ARTICLE Complex Vs Simple Carbohydrates

Soluble and insoluble fiber are also two forms of complex carbohydrates. Insoluble fiber also known as resistant starches promotes the movement of material through your digestive system and increases bowel movement. Essentially, it’s like a broom that sweeps your system, so you can easily pass bowel movements on a consistent basis. These undigested carbs are fermented by bacteria and produce short-chain fatty acids. Whole-wheat flour, wheat bran, nuts, beans, and vegetables, such as cauliflower, brussels sprouts, green beans, and potatoes, are all great food sources packed with insoluble fiber [R]. 

Soluble fiber comes from oats, peas, beans, and the fleshy part of fruits and veggies such as apples, carrots, and citrus fruits, and partially ferments in your gut. As it dissolves, it forms a gel-like material that passes through the GI tract slowing digestion and allowing better nutrient absorption. One of the benefits of soluble fiber is that it lowers cholesterol and maintains stable glucose levels.   

What Are Carb Blockers?

Carb blockers often referred to as ‘starch blockers’ block a specific digestive enzyme alpha-amylase that is needed to breakdown complex carbs. Amylase inhibitors prevent starches from being absorbed by the body. When amylase is blocked, those carbs pass through the body undigested, so you do not absorb the calories. This can be beneficial for weight management and those looking to reduce calorie intake. Unfortunately, carb blockers do not block simple carbs. 

When you chew carbohydrates your body produces the digestive enzyme alpha-amylase produced by the salivary glands. This process accounts for roughly 5% of the breakdown. Once the carbohydrates hit the digestive tract, glucosidase enzymes complete the process by further breaking down the carbohydrate to monosaccharide units which are absorbed by the body and stored as glycogen [R].

Do Carb Blockers Work?

There are two different types of carb blockers – dietary supplements and prescription medications. Prescription medications known as Alpha-glucosidase inhibitors (AGIs) are oral anti-diabetic drugs used for those with type 2 diabetes, that work by preventing the digestion of simple carbohydrates and starch controlling the release of glucose. Pharma starch blockers go by the name of acarbose (Precose) and miglitol (Glyset).

Supplemental carb blockers are derived from natural sources, most commonly extracted from white kidney beans, known as Phaseolus vulgaris. Studies have shown that white kidney bean extract, can block the digestion of carbohydrates by successfully inhibiting the digestive enzyme alpha-amylase [R]

But do carb blockers actually work? Can they really help you lose weight and block carbs from actually being absorbed? According to some research, they can.

Carb Blockers May Help Weight Loss

A handful of studies have shown that carb blockers using Phaseolus vulgaris can have a positive effect on overall weight loss. 60 overweight individuals were included in a 12-week randomized double-blind placebo-controlled trial. Subjects consumed two 500mg soft chews before each meal for a total of 3000mg of Phaseolus vulgaris per day. The study showed a statistically significant difference in weight loss between the control group and the active group. At 12 weeks, study participants in the active group lost anywhere from 6.9-7.9lbs with an average of 0.57lbs per week, while the control group gained 0.8lbs. There were no differences in body fat, or lean body mass [R].

A similar study which included 60 participants were divided into two groups and administered 445mg of Phaseolus vulgaris or placebo for 30 consecutive days before a carbohydrate-rich meal. Results showed that after 30 days, study subjects receiving Phaseolus vulgaris extract with a carbohydrate-rich diet had significantly (greater reduction of body weight, BMI, body fat mass, adipose tissue thickness, and waist,/hip/ thigh circumferences while maintaining lean body mass compared to subjects receiving placebo [R].

Other studies however showed inconclusive evidence and mixed results evaluating the efficacy of Phaseolus vulgaris as a weight loss aid. A comprehensive meta-analysis that analyzed several studies using white kidney bean extract stated that all eleven randomized controlled trials identified had serious methodological flaws. More research, with better study design, is needed in order to draw definitive conclusions [R]. Studies showing positive results were also funded by supplement companies, using their products, which can also admit study bias.

Should You Take A Carb Blocker? 

Ingestion of complex carbohydrates is not the problem. It’s the imbalance of energy intake and energy expenditure that results in weight gain. A low carbohydrate diet will help in weight loss, yet carb blockers do not block simple carbs, which are the real culprit in weight gain. Carb blockers only prevent a portion of carbohydrates you eat from being ingested. More often than not, those who are overweight are ingesting simple carbohydrates such as refined sugars found in packaged goods. Complex carbohydrates are only a small portion of most people’s diets. For the majority of overweight people, added sugars are the problem, which a carb blocker won’t help with.

RELATED ARTICLE Are Carbs Bad For You?

When carb blockers prevent the digestion of complex carbs, these carbs act very similarly to resistance starches. Resistance starches, or insoluble fiber, pass directly through the GI tract, without raising blood glucose. This is partly because white kidney beans, are a type of insoluble fiber.

Carb blockers also slow down the absorption rate of complex carbs, helping to further regulate blood sugar levels. Although, complex carbohydrates such as oats, sweet potatoes, brussels sprouts, broccoli, and quinoa are already slowly digested carbohydrates. Therefore a slower release seems to be a superfluous benefit at best.

RELATD ARTICLE 6 Incredible Clean Carb Sources To Improve Strength And Performance

Complex carbs are also the preferred type of carbohydrates when you're trying to maintain a healthy weight and create healthy eating habits. 

RELATED ARTICLE 5 Reasons Why You Should Eat More Carbs

What Are The Best Carb Blockers?

If you decide to use a carb blocker, it’s important to choose a supplement that uses Phaseolus vulgaris or white kidney bean extract.

You can choose from a list of different carb or stanch blockers supplements, yet nearly all clinical research showing positive results on weight loss have used white kidney bean extract. 

Most studies used a clinical dose of 500-3000mg per day, with the best results using two 500mg tablets three times per day before meals.

Supplements are classified as foods by the FDA, therefore Carb blockers like any other supplement are not regulated as closely or to the same standards as pharmaceutical drugs. If you choose to use a carb blocker, make sure you are buying from a reputable company and consult with your healthcare provider.

If you have diabetes, it’s important to consult your physician before adding any new supplement to your nutrition protocol, which may have an effect on blood glucose levels.

The Truth About Carb Blockers: Takeaway

Carb blockers may offer a quick-fix or solution for some but won’t offer long term results like a well-rounded nutritious diet. The best way to maintain a healthy weight is with long-term sustainable healthy eating habits and a positive relationship with food.

It's important to remember that complex carbs are important for overall health and wellness. Simple carbs and refined sugar are the carbohydrates you want to avoid, in order to mitigate weight gain. Unfortunately, carb blockers do not block simple carbohydrates. When you're trying to lose weight a diet consisting of healthy fats, lean proteins, and quality carbs is necessary to reach your goals. 

Instead of eating starchy carbs, try replacing your simple carbohydrates with vegetables, such as broccoli, cauliflower, sweet potatoes, and brussels sprouts. If you don’t like vegetables, try finding ways that may prepare them in more appetizing ways. Cauliflower mash and diced veggie mixes are a great way to eat more nutritious and avoid heavy carbs, which may cause weight gain. Weight management isn’t about food elimination, it’s about finding a balance.


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We believe that everyone can optimize not only their athletic performance but their human potential. The way we believe we can optimize performance is through transparency, clinically effective doses, and clinically proven ingredients with evidence-based outcomes. We provide the nutrients you need to power your active lifestyle.


Brown L, Rosner B, Willett WW, Sacks FM. Cholesterol-lowering effects of dietary fiber: a meta-analysis. Am J Clin Nutr. 1999;69:30-42. 

Rothacker D. Reduction in body weight with a starch blocking diet aid: StarchAway comparison with placebo. Leiner Health Products; 2003. http://www.phase2info.com/pdf/Phase2_Study6.pdf Ref Type: Online Source. [Google Scholar]

Barrett, Marilyn L, and Jay K Udani. “A proprietary alpha-amylase inhibitor from white bean (Phaseolus vulgaris): a review of clinical studies on weight loss and glycemic control.” Nutrition journal vol. 10 24. 17 Mar. 2011, doi:10.1186/1475-2891-10-24

Celleno L, Tolaini MV, D'Amore A, Perricone NV, Preuss HG. A dietary supplement containing standardized Phaseolus vulgaris extract influences body composition of overweight men and women. Int J Med Sci. 2007;4:45–52. [PMC free article] [PubMed] [Google Scholar]

Onakpoya I, Aldaas S, Terry R, Ernst E. The efficacy of Phaseolus vulgaris as a weight-loss supplement: a systematic review and meta-analysis of randomised clinical trials. Br J Nutr. 2011;106(2):196-202. doi:10.1017/s0007114511001516


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