Do Starch Blockers Work?

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It's a dieter's dream: A pill that makes carbs disappear. And there are several vendors who will happily sell you what they claim is just such a pill. The Los Angeles times ran an article on June 24, 2003, titled "Starch Blockers show Promise for Dieters" The article suggested that over-the-counter supplements containing an extract from beans could stop the body from digesting carbs. The article suggests these expensive supplements are perfect for Atkins dieters. Quoting the physician author of "The Starch Blocker Diet" the article says, "Taking a starch-blocking a way to make Atkins doable," and indeed, if a drug could let you eat carbs without their getting into your body, it would be the low carber's dream drug--or would it?

Examine the Source

Unfortunately, a close reading of the article shows that the study it was based on was small, not peer reviewed, and that its results were not statistically significant. Even more telling, a little googling shows that the doctors quoted in the article are associated with a supplement company actively promoting starch blockers as a dietary cure-all.

Both the doctor who conducted the study that is the centerpiece of the article and the author of the starch blocker book appear at presentations sponsored by this company. These are probably paid appearances and cast some doubt on these doctors' impartiality. At the end of any article published by a reputable medical journal there will be a disclosures paragraph which will reveal if the researchers were paid by the company making the supplement. Such studies are not considered as reliable as those conducted by independent researchers. You can to check out the relationship between researchers and the supplement company by reading the relevant disclosure paragraphs found HERE.

At the company's web site you will see several "clinical studies" listed, all funded by the company. Only one of these studies was peer reviewed. It was conducted by "The Cosmetic Research Center" in Italy. The rest are "vanity" research, paid for by the manufacturer and not published anywhere. If you read the one published study closely you will see it was also run by the manufacturer and designed to use carefully selected subjects who were NOT very overweight. It ran for a very short time, and showed a very small loss of weight which was consistent with the water weight lost by all beginning dieters.

Besides the studies the company paid for where they carefully cherry-picked the participants and probably massaged the data until they got the result they were looking for there is nothing available on the web to support the idea that these supplements work, and quite a few quotations from other researchers citing studies that have showed them to be ineffective. Mostly what you see is high praise posted on web sites that sell the product. At best these extracts may simply be another source of fiber. And about as effective as taking Metamucil with your lunch--though much more expensive. If you want to slow down the digestion of carbohydrates, you'd do a lot better to do it by eating a lot of green leafy vegetables.

In short, it looks very likely that someone at the LA Times was not doing their homework and simply parroted a press release supplied by Phase2, who engineered it to give their expensive supplement a push.

The Reality

Unmentioned in the article is the fact that there does exist a prescription drug that has been proven in peer reviewed studies to slow--not block--the digestion of starches. But it's important to note that the peer-reviewed studies that have examined this drug have not found that it has any effect on weight loss. The drug is Precose (generic name "acarbose").

Prescription Drugs that Slow Starch Breakdown

Precose is one of a family of drugs which include Glyset and Glucobay. It does something very close to what the "starch blockers" claim to do. To quote the prescribing information for Precose, "Acarbose is a man-made oligosaccharide designed to slow down the actions of alpha-amylase and alpha-glucosidase enzymes thereby slowing the appearance of sugar in the blood after a meal." By slowing down the digestion of starches and complex sugars it prevents the generation of the high blood sugars that are believed to cause diabetic complications.

Peer reviewed studies have shown that people with diabetes who take Precose can lower their blood sugars and reduce the incidence of neuropathy. However, the effect of the drug is so moderate that it has only been shown to be effective in moderating blood sugar when taken in conjunction with other, far more powerful, drugs that increase the body's secretion of insulin. People taking Precose have also been found to experience slight decreases in blood pressure. But no study showed that taking Precose caused any increase in weight loss.

My own experience with Precose bears this out. I was able to control my blood sugar while taking it. I also was able to boost my daily carb intake without gaining weight for many months--as long as I kept my caloric intake moderate. But while I could avoid weight gain while taking it, Precose did not help me lose any weight. To do that I have had to cut my carbs down to a very low level.

The Real Reason to Use These Drugs

Despite its failure as a weight loss drug, Precose can be a very helpful drug for people with diabetes. The reason is because, unlike a low carber with a normal metabolism, someone with diabetes can seriously injure their health when they raise their daily carb intake by as little as 15 grams a meal. That's because there's increasing evidence that blood sugars higher than 140 mg/dl (7.8 mmol/L), sustained for a few hours, can poison cells. Unfortunately, many people with diabetes will experience levels much higher than 140 mg/dl (7.8 mmol/L) when they eat as little as 20 grams of carbs at one time.

That is where Precose can be helpful. Once a person with diabetes has achieved their low carb weight goal, an occasional dose of Precose can let them boost their a one time carb intake to a moderate level--30 grams, for example--enough to enjoy a scoop of ice cream or a dinner roll, without having to worry about endangering their health.

But Precose is not a diet aid. And it isn't for everyone.

Side Effects of Prescription Drugs that Block Starch Breakdown

Unmentioned in the "starch blocker" hype is a very important point. The most common side effects of these effective prescription medicines are intense, and, at times, intolerable, gas and diarrhea. Why? Because when starches and sugars pass into the intestine undigested they encounter a whole ecosystem of bacteria and yeast that can and do digest them. This process is known as "fermentation" and its end product includes a lot of carbon dioxide--the same stuff that makes your beer fizzy. Unfortunately, when it is produced by microorganisms fermenting starches in your gut, the result is not fizziness but something far more explosive.

The effect is similar to what happens to many people when they eat another "undigested" carb--the sugar alcohol. In fact, the number of people who had severe gastrointestinal reactions of Precose when it was first introduced was so huge that the company that makes it stopped the ad campaign for the drug and pretty much abandoned marketing it. As a result, very few doctors ever think of prescribing it. It is probably only of use to people like myself with "cast iron" stomachs who can swill down sugar alcohols without problems. Even then, I have to be very careful to limit how much Precose I take because overdoing it is extremely unpleasant.

So the bottom line here is this: If a starch blocker really works, you'll know because it will give you killer gas when the undigested starch hits your intestines. No over-the-counter supplement can block the digestion of starch and sugar by microflora in your gut.

Beyond that, the bean-derived starch blockers work in the stomach, but there are also enzymes in the gut which continue the process of carbohydrate breakdown. So eventually the carbs from the complex sugars and starches that you supposedly blocked will get into the blood stream where they will refill glycogen in your liver and muscles, kick you out of ketosis, and erase the benefits of a truly low carb diet.

If it Sounds Too Good to Be True . . .

Unscrupulous supplement companies prey on dieters who want to lose weight without changing their eating habits. Be suspicious whenever you see the telltale slogan, "Eat all you want and lose weight."

No one is going to get rich telling you that successful weight loss requires that you change the way you eat, cut down your portion sizes, and increase your exercise. You'll only hear that advice from people who have taken off a lot of weight and kept it off for years. But that kind of advice is not likely to make newspaper headlines.
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