Breads and Pasta Making You Fat?

In the early 2000s, starch blockers started to become incredibly popular amongst dieters as a way to lose weight easily.  This trend coincided with fad, low-carb diets like Atkin’s and South Beach.  Over a decade later, carbohydrates are still overwhelmingly being rebuked as the root of the obesity epidemic and starch blocker supplement sales continue to soar.  But do these carb blockers really live up to all the hype around them?

What are Starch Blockers?

Starch blockers, also called carb blockers, are weight loss supplements which claim to inhibit the body’s absorption of carbohydrates.  Virtually all starch blockers contain phaselous vulgaris which is an extract from white kidney beans. According to supplement claims, a natural chemical in white kidney beans interferes with the enzymes needed to turn carbohydrates into glucose.  Instead of being broken down by the body, the carbs will pass through the digestive tract and get excreted as a bowel movement. Some of the more outlandish claims of starch blockers include “Cut Out Up to 255 Grams of Carbs From Any Meal With One Pill” – despite the fact that there is no evidence to back up these claims.

It is anyone’s guess as to how effective these starch blockers really are.  Starch blockers sold for weight loss are not the same as the prescription starch blockers used for managing diabetes.  Unlike prescription drugs, supplements do not have to prove their effectiveness to the FDA in order to get approval.  There have been some positive clinical studies supporting white kidney bean as a starch blocker in lab tests. However, when tested in humans, there is no evidence of decreaesd carbohydrate absorbtion or a decreased rise in blood glucose.  Because of this, many nutritionists are hesitant to recommend starch blockers and others outright dismiss them.

If starch blockers are as effective in blocking carb-to-glucose conversion as they claim, then excess carbohydrates would enter into the large intestine.  There, the carbohydrates would begin to ferment and cause gas to form.  As with fat blockers (fat blockers: can you really eat all the fatty foods you want and still lose weight?), users could expect some unpleasant side effects like flatulence, bloating, and diarrhea.

Are Starch Blockers Worth It?

Even if starch blockers don’t live up to all of their promises, they probably are effective in blocking some carbohydrate absorption and thus can reduce calories from all those starchy foods which dominate the western diet.  Dieters should always be aware that no weight-loss supplement is a substitute for a healthy, balanced diet and exercise.  By relying too much on carb blockers, dieters could overlook the bigger picture of healthy weight loss.  Instead of choosing those “junk” starches like white breads and pastas, they should be opting for whole grains instead.

Contrary to what the makers of starch blockers would have you think, carbohydrates are not inherently evil.  We need carbohydrates to fuel our bodies and provide us with essential nutrients.  Carbohydrates only become a problem when we eat too much of the wrong types.  Simple carbohydrates – like refined sugars and white breads – are quickly broken down by the body and cause surges in blood sugar.  If the energy isn’t used, then it gets stored as fat.  Further, you will feel hungry again much faster as your blood sugar levels drop quickly. Complex carbohydrates – like those whole grains you hear praised so often – are broken down more slowly by the body.  Instead of getting surges in blood sugar, you get sustained energy and a longer-lasting feeling of fullness.

So what is the bottom line on starch blockers?  They probably have minimal, if any, effect on the amount of carbohydrates you absorb from your diet.  Also, if it did work to any significant degree, you will pay for these choices with some nasty side effects and still not get great results from the starch blocker. You are probably better off choosing healthy carbohydrates instead of relying on the starch blocker.


Celleno, Leonardo, Maria Vittoria Tolaini, Alessandra D’Amore, Nicholas V. Perricone, Harry G. Preuss. “A Dietary Supplement Containing Standardized Phaseolus vulgaris Extract Influences Body Composition of Overweight Men and Women.” International Journal of Medical Sciences 4 (2007): 45-52. Web.

Baca, Joseph R.  “Warning Letter for Weight Loss Products “Starch Blocker 1000 Ultra Carb Blocker”.” Web. 27 Nov. 2011. <http://www.fda.gov/Food/GuidanceComplianceRegulatoryInformation/ComplianceEnforcement/ucm188422.htm>.


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