Best Carbohydrate Blocking Diet Pills

Last updated January 29th 2015

There are very few diet supplements on the market that target carbohydrate blocking. However, the few that do are proving very effective at helping weight loss.

Carbohydrate blocking is one of the four main ways in which diet pills target weight loss. Carbohydrate blocking products tend to work by physically blocking carbohydrates from being absorbed. Although they cannot prevent all carbohydrates consumed in the diet from being absorbed, they can make a significant difference to the amount absorbed by the body, resulting in a lower calorie intake and less weight gain. Some carbohydrate blockers claim to be able to block as much as 80% of consumed carbohydrates from being absorbed. This article will help your to understand exactly how carbohydrate blocking products claim to work, and whether or not they might be a useful addition to your weight loss regime.

What Is Carbohydrate Blocking?

The modern diet in western countries generally includes a large amount of carbohydrates, and consuming starchy foods can be the downfall of many peoples’ weight loss regimes. When too many carbohydrates are consumed, the body converts any excess carbohydrates into fat. Carbohydrate blockers are thus designed to prevent the carbohydrates consumed in the diet from being absorbed by the body. These products purport to prevent the release of alpha amylase, a digestive enzyme that is responsible for breaking down carbohydrates from starchy foods, such as pasta, potatoes and cakes.

Carbohydrates are large molecules, and in order for them to be absorbed, they must be broken down in to individual sugars (such as glucose). Consequently, by blocking this enzyme, some of the carbohydrate complexes are not broken down, meaning that they remain too large to be absorbed through the membrane of the small intestine. Carbohydrates that are not absorbed are instead excreted from the body as a waste product after passing through the intestines and leaving the body through bowel movements.

Taking diet pills with carbohydrate-blocking qualities could result in the body not getting as many carbohydrates as it is used to, and so it may turn to fat stores for energy.   The ingredient that is responsible for blocking the release of alpha amylase is nearly always an extract from white kidney beans. Some carbohydrate blockers also contain an ingredient called Chitosan, which works in a similar way to dietary fibre in that it is able to pass through the digestive system without being absorbed.

Would Carbohydrate Blocking Products Suit You?

With so many weight loss supplements available to buy on the market, it can prove extremely difficult to choose between them, and work out precisely which one may be best for you. Carbohydrate blockers will only have a noticeable impact on your weight loss regime if carbohydrates constitute a significant part of your diet. Although it is always recommended that you incorporate as much exercise as your can in to your life whilst trying to lose weight, in theory, carbohydrate blockers may make a small difference to helping you maintain a healthy weight even if you do not undertake a large amount of exercise.

If you consume more fatty foods in your diet, then fat burners and binders may prove more useful for you. Fat burning products usually purport to work by increasing the activity of enzymes that break down fat molecules once they have been absorbed in to the body. This is usually achieved through the process of thermogenesis – increasing the internal temperature in the body, making it optimum for the activity of these enzymes. Fat binders on the other hand, generally work by joining to the fat molecules in the digestive system, usually forming a fat-fibre complex that is too large to be absorbed through the small intestine lining. In turn, the molecules pass through the digestive system and are excreted in the stool. The effectiveness of each of these products will be increased if consumed alongside a healthy diet and regular exercise.

Alternatively, if you believe that you have a relatively well balanced diet, you just consume too much, then it may be worth looking in to appetite suppressants and metabolism boosters. Appetite suppressing products usually work by altering the concentration of certain neurotransmitters related to the appetite, such as serotonin, in the brain. This results in the brain signalling to the body that you are not hungry. Other appetite suppressing products can work by expanding in the stomach, making your body feel full. The trick is that this substance in the stomach is insoluble, and so will not be absorbed by the body, instead it will be passed in the stool.

Metabolism boosters work in a similar way to fat burners. These products generally claim to increase the speed at which fat molecules are broken down, and also, usually via the process of thermogenesis, increase the activity of cells in the body. This means that cells should use more energy and so burn more calories. If you are a very active individual, then fat burners and metabolism boosters would be recommended. These are both most effective when consumed alongside a significant amount of exercise, and if used correctly, could speed up the process of weight loss. For more information on which type of diet pill is likely to suit you best, look at the article, ‘Best Diet Pills’.

Side Effects of Carbohydrate Blockers

As with all weight loss supplements, there is the possibility that carbohydrate blocking products will cause side effects. Exactly what these side effects will be is dependent upon what ingredients are present in the product; nevertheless, some generalisations can be made based on the activity of carbohydrate blockers in the body. The most common side effects associated with carbohydrate blockers are related to the gastro-intestinal tract. For example, diarrhoea, constipation, flatulence, bloating, nausea, gastro-intestinal discomfort, and stomach cramps. It has also been suggested in the past that carbohydrate blockers may interfere with the absorption of some fat-soluble vitamins, such as A, D, E, F, and K, so look out of effects associated with vitamin deficiencies, such as anaemia, skin conditions, and inability of blood to clot. Also keep a close eye on your blood pressure and cholesterol levels

Is there anybody who shouldn’t take Carbohydrate Blockers?

It is recommended that people who are under the age of 18, pregnant, or breast feeding, should not consume any weight loss supplements. If you have any pre-existing medical conditions, or are taking any form of medication, then a doctor should be consulted before any weight loss pills are consumed, as these products can interact with certain drugs, and worsen certain conditions. In the case of carbohydrate blockers, it is probably best to avoid products claiming to work in this way if you suffer from any condition relating to the digestive tract, such as irritable bowel syndrome.

If you are allergic to shell fish, avoid products containing chitosan. Remember that some products that are advertised as carbohydrate blockers may also target other areas of weight loss, and so may be associated with other side effects and have different interactions with the body.

How to Spot a Good Carbohydrate Blocker

There are lots of diet pills available on the market, and many of these claim to work as carbohydrate blockers. Before choosing the pill that you think will be right for you, be sure to research the available products. It can be very difficult to decide on an exact product, but there are several factors that you should weight up before coming to a decision. First and foremost, you want to know whether or not the product has been shown to work. The best way to do this is to look up any scientific studies on the product. Most weight loss supplements have not been the subject of scientific studies as a whole, and if this is the case for the product that you are looking at, then you should search for studies on its active ingredients.

Without trawling through scientific journals, it is possible to find this information on the Healthy Compare website. Simply search for the product that you are considering and read the thorough review provided, which should include information on any clinical trials that have been performed on the product/ ingredients. The other way to determine the effectiveness of a product is by looking at independent customer reviews, written by people who have tried the product in the past. These are likely to be varied, as no one product will work best for everybody, however they can give you an idea of the types of people that it does work for, how many of the reviews are positive, and may also provide you with an idea of the potential side effects of the product. Be sure to read a selection of reviews that give high ratings as well as those that give low ratings.

To ensure that the product you are buying is safe, it is generally recommended that you purchase weight loss supplements from well known high street stores rather than from independent online stores. If you do choose to buy the product from a website, make sure that the company is reliable. The best ways to do this are by checking customer reviews of the company, looking for contact details (including a postal address, phone number, and email address, not just an online form), and looking for information on the history of the company.

Also be sure to research the manufacturer of the product, as this will not always be the same company as is selling the product. Check for the same things on the website of the manufacturer, and ensure that the product is created in a safe environment. Scams are renowned for being associated with a number of diet pills online; for more advice on how to avoid diet pill scams, see our article, ‘Diet Pill Scams’.

Ingredients common to Carbohydrate Blocking Diet Pills

Although each individual product will vary, there are some ingredients that are present in the majority of carbohydrate blocking diet pills on the market.

Phaseolus vulgaris (white kidney bean extract): The most prominent of these is phaseolus vulgaris (or phaseolamin), which is an amylase inhibitor sourced from beans, usually the white kidney bean. The substance is believed to bind to the enzymes involved in the breakdown of carbohydrate complexes. A number of scientific studies have been performed on the ability of the ingredient to work in this way.

A study published in 2009 was performed to determine the effectiveness of a dietary supplement containing 445mg of Phaseolus vulgaris extract on the body composition of overweight humans. 60 slightly overweight subjects were used, who had been at approximately the same weight for six months or longer. The subjects were allocated to either a test or placebo group. The test group were given the product containing Phaseolus vulgaris extract whilst those in the control group were given a placebo once a day for 30 days. The results suggested that the consumption of Phaseolus vulgaris significantly increased the amount of weight lost.

Another clinical trial on the substance found that individuals who consumed 1000mg of proprietary fractioned white bean extract lose significantly more weight over a 40 day period than a placebo group when taken alongside a weight loss programme with diet, exercise, and behavioural intervention. It should be mentioned however that this study only used 25 subjects – this is not a large enough number for the study to be deemed proof that the substance works.

A review of the impact of Phaseolus vulgaris on weight loss and glycemic control can be found here. The authors state that the substance has been shown to induce weight loss at doses of between 500 and 3000mg per day. It may also have the ability to reduce post-prandial blood glucose spikes. It also mentions that at the time of writing (2011), no serious side effects had been reported following consumption, and gastro-intestinal side effects do occur, but are not common and usually get better with time.

Overall, it seems that Phaseolus vulgaris has the potential to help people to lose weight through its activity as an alpha amylase inhibitor (carb blocker). A selection of studies has been discussed, but there are a large number available, and the majority of these seem to have shown that the ingredient has the potential to help treat obesity.


Chromium picolinate: Another common ingredient in carbohydrate blocking products is chromium (also called chromium picolinate); this is an element that plays a role in the maintenance of carbohydrate and lipid metabolism in humans. A review of scientific studies on chromium and weight loss can be found here. The authors of this study state that the effectiveness of chromium picolinate is intensely debated, and not all studies have shown positive results. It also warns about recent in vivo studies on rats that suggested that the substance may induce damage to DNA and lipids, but precisely how accurate these results would be for humans is not known.

A study assessed the impact of chromium picolinate alone and when combined with a diet plan, on weight loss in overweight adult subjects. 80 subjects were used in this randomised, double blind, placebo controlled trial. Individuals in the test group were given 1000μg of chromium picolinate whilst those in the control group were given a placebo for 24 weeks. After 12 weeks, all subjects were given nutritional education. The results of the study suggested that the individuals taking chromium picolinate alone, or in combination with nutritional education, saw no impact on weight loss when compared to the control group.

A meta-analysis of randomised trials on chromium picolinate reviewed ten trials, all of which were randomised, double blind, and placebo controlled. Their statistical analyses suggested that the substance did help people to lose weight, but that these results were largely influenced by one trial. The authors concluded that the substance may have a small effect on weight loss when compared to a placebo, but that the evidence is debatable, and more studies need to be performed to back this claim up.

It is safe to say that overall, the impact of chromium picolinate supplementation on weight loss in overweight adults is debatable, and the results of studies have been contradictory. The substance may be useful for some people, but will not undoubtedly help everybody who consumes it to lose weight.


Chitosan: The final ingredient common to carbohydrate blocking products is chitosan. This is a substance that is sourced from the shells of shrimp, crabs, lobsters, or other shellfish. Although it is principally advertised as a fat binder, it can also regularly be found in carbohydrate blocking products. Chitosan has not been the subject of as many scientific studies as the previously mentioned ingredients; however a few have still been performed.

One such study was performed on 34 overweight adults to test the effectiveness of chitosan on weight loss. The trial was randomised, double blind and placebo controlled. Subjects were given either four portions of chitosan or a placebo twice daily for 28 days. No dietary restrictions were enforced. The results suggested that the substance makes no significant difference to weight loss when compared to a placebo. They also did not report any adverse effects associated with the substance.

A comprehensive review of studies on the impact of chitosan on weight loss is available here. The paper reviews 14 randomised, placebo controlled trials performed on overweight or obese subjects over a minimum of four weeks. Statistical analyses of these trials suggested that overall chistosan has a significant impact on aiding weight loss in subjects when compared with placebo, although this impact is still only small. When they restricted the analysis to only high quality studies, the reductions in weight with chitosan were lower, and its impact is only minimal.


Weight loss supplements available on the market target several different areas of weight loss, and carbohydrate blocking is a popular one of these. Before deciding on a weight loss product it is important to ensure that you are choosing one that is likely to work well with your lifestyle, diet, and health. Some of the ingredients regularly found in carbohydrate blocking products have been shown to be effective in scientific studies (such as Phaseolus vulgaris), whilst others have seen less positive results (such as chitosan). Make sure that you find a product that is safe, and remember that what may work for one person is not guaranteed to work for another.