Let’s start with what ‘carb blockers’ actually are – they are a diet supplement which can help block the enzymes that are needed to absorb certain carbohydrates. Normally they are made from a group of compounds called alpha-amylase inhibitors, which occur naturally. These compounds are mostly commonly found in a white kidney bean extract known as phaseolus vulgaris.
How do they work?
Carbohydrates can be caterogised in two ways – simple and complex.
Simple carbs are found in natural foods like milk and fruit as well as processed foods like desserts and soda.
Complex carbs are found in foods like pasta, bread, rice and starchy vegetables like potatoes. Complex carbs are made up from chains of simple carbs. That’s where the enzymes are needed – to break down those chains in order to digest the simple carbs.
Carb blockers are used to prevent the process of breaking down the links and as a result, the carbs pass through into the large intestine without being absorbed. This way they do not raise blood sugar and do not contribute energy or calories to the body.
Can Carb Blockers Help you Lose Weight?
Carb blockers are usually marketed as a weight loss tool that allows you to eat carbohydrates without the associated weight gain or spike in blood sugar. However studies have shown conflicting results.
Here is a breakdown:
Carb blockers prevents a portion of the carbs you eat from being digested – not all of them. They have been shown to block between 50–65% of carb-digesting enzymes (5).
This study presented conclusions that while a strong carb blocker inhbited 97% of the enzymes, it actually only stopped 7% of the carbs from being absorbed.
Therefore it is important to note that inhibiting those enzymes does not necessarily result the same amount of carbs will being blocked.
This is because these blockers increase the amount of time is takes for the enzymes to digest the links in the complex carbs, rather than making them indigestible altogether.
Also, only complex carbs are affected by carb blockers and those make up only a portion of the carbs in most people’s diets. Generally for weight loss, added sugars from processed foods are the larger issue. Added sugars are always simple carbs like glucose, sucrose and fructose which are not affected by carb blockers.
However there have been studies linking carb blockers to weight loss.
It was actually the people eating more complex carbs who lost the most weight which supports the process of carb blockers – where the more complex carbs make up your diet, the better the blockers will work for you.
Carb blockers have also been shown to suppress appetite by making you feel fuller for longer. Studies have found that a carb blocker supplement can decrease the volume of food rats ate by 15–25% over a consistent period of time and even caused them to eat less high fat and sugar foods. This could be because it slows the digestion of complex carbs, helping you eat less and lose that weight.
There have also been links between carb blocker and controlling blood sugar. This is due to both preventing the digestion of some complex carbs as well as the slowing the absorption of complex carbs which can smooth out spikes in blood sugar. This study showed that carb blockers help return blood sugar levels back to normal more quickly.
Unfortunately these studies are not very robust and other studies have shown no evidence of significant weight loss for those taking the supplements and those who aren’t. Overall, more high quality studies are needed to draw proper conclusions.
Are Carb Blockers Safe?
Carb blockers are considered very safe and have minimal side effects however as they slow digestion and inhibit the absorption of some foods – some side effects include diarrhea, bloating, flatulence and cramping (1, 5). The carbs get fermented by bacteria in your large intestine producing gas.
These side effects are usually not severe and reduce over time, but they are enough for some people to stop continuing to take carb blockers.
It’s important to note that anyone with diabetes who take insulin must consult a doctor before taking carb blocker supplements. This is because there is a chance they could cause low blood sugar if the insulin dose is not adjusted which leads to serious complications.
Another issue is supplement regulation.
It is the supplement manufacturers who are responsible for the safety and reliability of their products, and so there have been many cases of fraud throughout the supplement industry.
The FDA recently inspected a number of herbal supplements and found that only 17% of the products actually contained the main ingredient listed as the active ingredient.
Historically the FDA has even found some dietary supplements had been contaminated with prescription medications that had been removed from the market due to dangerous side effects. These harmful medications had been added in an attempt to make supplements including body building, weight loss and sexual enhancement supplements more effective.
So for this reason it is important that you are careful when purchasing carb blockers as their labels may not be telling the whole truth. When turning to supplements, it is recommended to do thorough research
Should You Take a Carb Blocker?
As discussed, a few studies have suggested that carb blockers help you with a small amount of weight loss, as well as reduce appetite and lower blood sugar levels. However the quality of these studies are not high enough to quantify whether carb blockers have any long term effects. In addition, they are only helpful for those on a diet high in complex carbs.
Remember that carb blocker supplements are just that — supplements. The real answer is a healthy lifestyle balanced with diet and exercise are the key ingredients for achieving last results.