Beware of "Net Carbs"!
Every drugstore, supermarket, and department store in U.S. is filled with snack products that claim to be perfect for low carb diet. The labels on these products may list 24 grams of carbs but assure you that you only have to count 2 or 3 of these grams in your daily carb allotment. They may call these carbs "low impact carbs" or "net carbs" and display them prominently on the front of the product, but the carb count on the nutritional label--the only one that the FDA regulates will list a far higher carb count.
If these disappearing "net carbs" make you suspicious, you may prefer to buy products that list only a gram or two of carbs in their nutritional information. But a look at their ingredient list may show that mysterious substances like maltitol, glycerine or polydextrose are major ingredients of these bars, too--exact same substances reported on labels of bars that claim "3 grams of Net Carbs" on the front of the package and list 20-something grams of carbs in their nutritional information panel.
What's Going on Here?
Most of these "low carb" products are sweetened with substances called "sugar alcohols." Maltitol, lacitol, and sorbitol are some of names of these sweeteners. Despite the name, these aren't sugars or alcohols. They are hydrogenated starch molecules which are a byproduct of grain processing.
These sugar alcohols are manufactured by the three large agribusiness companies: SPI Polyols, Roquette America, Inc. and Archer Daniels Midland. Having saturated world with high fructose corn syrup, these giant corn-producing companies have now turned to hydrogenated corn starch molecules as yet another way to wring profits out of surplus corn.
Despite wrapper claims, these sugar alcohols are metabolized. Each gram of a sugar alcohol turns into anywhere from less than 1 to as much as 3 calories. Erythritol comes in lowest, delivering less than one calorie per gram. Maltitol--the sugar alcohol found in most "low carb" foods is the highest, delivering 3 calories per gram. That is only a bit less than 4 calories you find in regular sugar and starch.
It is because these sugar alcohols can be metabolized as carbohydrates that US law requires that they be reported as carbohydrates on nutritional labels and why their calories are included in calorie counts.
Several years ago, after the FDA fined Atkins Nutritionals for ignoring the 20+ grams of glycerin found in their product in the nutritional panel of their Advantage Bars, the company invented the "Net Carbs" designation that it now places on the front of wrappers--but not on the nutritional panel. This ruse was so successful, they went on to license the use of this phrase and the Atkins "A" to other companies so that they too could continue deluding customers about the carb content of their foods.
Small print on back of these label explains that fiber and sugar alcohols have a "negligible effect on blood sugar". This, they suggest means that you can ignore them, and magically converts foods that have 24 grams of carbs--and the associated calories--into foods with a diet-friendly 3 grams.
If it were true that these foods did not raise blood sugar, it would make them ideal for the low carb diet. However, it is not always true. Some lucky people can eat these low carb treats and still lose weight on a low carb diet. But hundreds of people who have stopped by the alt.support.diet.low-carb news group to ask why their weight loss has stopped cold, discover that it is these sugar alcohol-laden low carb junk foods that have caused their long-term stalls.
The reason for this, is quite simply, that sugar alcohols, particularly Maltitol, the one that is most common in these products, can have a very significant impact on blood sugar. This isn't speculation. It's a fact. Many people with diabetes, who track any rise in their blood sugar with a blood sugar meter, find that these products cause a significant rise in their blood sugar, contrary to the label claims.
I'm one of them. My blood sugar rises almost as high when I eat a maltitol-sweetened Russell Stover "No Sugar" candy as it does if I eat a regular Russell Stover candy of same size. The only difference is that it takes two hours for the blood sugar rise to occur when I eat the "no sugar" candy compared to the one hour that it takes when I eat regular candy. So much for "truth in labeling."
I am not only person who has found this to be true. Fran McCullough warns readers of the very high blood sugar spikes reported by diabetics after eating glycerine-containing Atkins bars in her book, Living Low Carb
A comprehensive review published by the Canadian Journal of Diabetes
gives a very good overview of the scientific research into how sugar alcohols affect both normal people and people with diabetes. Sugar Alcohols and Diabetes: A Review.
Note the finding, on Page 5, that research shows that chocolate bars sweetened with maltitol raised the blood sugar of normal people as high as did chocolate bars sweetened with sucrose--table sugar.
However, there are other people with diabetes who report that they don't see a blood sugar rise when they eat foods containing these sugar alcohols. They find these products give them a way to incorporate legitimate treats into their diets and are grateful that they are now so plentiful.
There are also a number of successful low carbers who report in diet newsgroup that they have been able to lose significant amounts of weight while including these "low carb" treats in their food plans on a daily basis. You will often find them railing against "puritanism" of those who warn new dieters against them.
So, clearly these products do not affect everyone in same way. For some people they are a godsend. For others, they turn out to be "Stall in a Box."
Why Do Sugar Alcohols Only Affect Some People?
Since it seems that only a subset of the population metabolizes sugar alcohols as sugar, it is quite possible that some people lack some enzyme(s) needed to digest them and turn them into blood sugar. Since those people's bodies can't turn these sugar alcohols into glucose, they do not experience a blood sugar rise when they eat them.
Lending some support to this idea is fact that some of the people who report that they did not experience a blood sugar rise when they ate a product with a sugar alcohol in it, add that they experienced intense diarrhea or gas later on. These are classic symptoms of what happens when starches pass undigested into lower gut where they may be fermented by bacteria (causing gas) or suck water out of cells lining the colon (causing diarrhea).
Many of us who do get blood sugar rise do not experience this diarrhea. Our digestive enzymes appear to be able to break down these hydrogenated starches into glucose--though given the time lag, this happens slowly.
Diabetes expert David Mendosa has a very interesting web page at http://www.mendosa.com/netcarbs.htm
that points out "If the sugar alcohols had no impact on our blood glucose, they would have a glycemic index of zero.
With the the December 2003 publication of Geoffrey Livesey's amazing review of sugar alcohols, we now know a lot more about them than ever before. Mendosa cites the article, "Health potential of polyols as sugar replacers, with emphasis on low glycemic properties
in Nutrition Research Reviews 2003;16:163-91.
Mendosa goes on to say,
Only two of the sugar alcohols have a GI of zero, according to Livesey's research. These are mannitol and erythritol. Several others have a very low GI, but two maltitol syrups have a GI greater than 50. This is a higher GI value than that of spaghetti, orange juice, or carrots.
What about Glycerine?
Glycerine is another sweet additive that manufacturers add to low carb bars. Here again, you'll find that, because manufacturers claim glycerine does not raise blood sugar, they omit it in the carb section of the label information or, if they do list it, they do not include it in number of diet-counted "impact" carbs. (Glycerine is sometimes spelled Glycerin and is another name for glycerol.)
As Lee Rodgers, proprietor of The Low Carb Retreat
explains that it is only true that Glycerine does not raise blood sugar when people are not low carbing. Rogers states:
1. When liver glycogen is full, glycerol is converted to fat.
2. When liver glycogen is empty, glycerol is converted to glucose.
3. And sometimes just goes right through without doing anything
In short, if you are in ketosis (having emptied your liver of glycogen, its stored carbs) glycerine is likely to turn into blood sugar, and then, of course, it raises insulin, defeating mechanism by which low carb weight loss takes place.
What about Fiber?
Perhaps the most confusing part of new "net carbs" designation is that it combines sugar alcohols and fiber in the same designation. This is unfortunate.
Fiber, unlike sugar alcohols, is not metabolized into a significant amount of calories and does not turn into blood sugar. Therefore it can usually be deducted from a food's total carb count.
But even here, a lot of caution is required. That's because labeling laws outside United States often treat fiber differently. In many European countries, fiber is already deducted from the label's total carb count. For example, imported Scandinavian bran crackers that list 3 grams of carbohydrate and 3 grams of fiber do not contain zero grams of carbohydrate. If they followed U.S. labeling conventions, their labels would show 6 grams of carbohydrate and 3 grams of fiber, since the European labels have already deducted the fiber from the total. This is also true of many imported chocolates.
To make it even more confusing, an increasing number of U.S. labels also deduct fiber from total counts, too. Many nuts do this, but so do premium chocolates. For example, despite fact that most labels for walnuts usually list "3 grams total carbohydrate, 3 grams fiber" walnuts are not a zero carb treat! They contain about 2 grams of carbohydrate per ounce.
In 2008 a brief scan of supermarket labels revealed that the habit of listing total carbohydrates with the fiber already deducted
had spread to many common foods. I found this to be true on squash labels and bean labels. Hardly premium European imports!
How To Detect if Fiber is Already Deducted on a Label
If you have any doubt about whether to deduct fiber, a simple solution is this. Use a "hidden carb calculator."
There are many on the web including some freeware you can download to your computer. Here is one:Low Carb Diet Tools - Hidden Carbs Calculator
Plug in the "total carbohydrate" count from your label and if the actual carb count is higher than the stated count and matches the fiber total, assume the label already deducted carbs.
Net Carbs and Restaurant Food
Where "net carb" designation becomes truly dangerous is in restaurants because new "low carb" restaurant menus do not give you complete nutritional data or any hint of an item's ingredients, only the "net carb" count.
So for all you know, that "3 gram net carbs" cheese cake may contain 40 grams of maltitol, which is the equivalent of 30 grams of sugar. Nor can you distinguish between a food that contains 10 grams of fiber and one that contains 10 grams of a lacitol, the sugar alcohol many dieters have found causes profound diarrhea.
All you know when you see that "net carbs" designation is that the carb count of the food you are about to eat is much higher than what restaurant would have to report were it giving you legal carb counts. You can hope that the additional carbs are fiber, but you may very well be wrong.
Another problem with restaurant carb counts is that they do not reveal what the portion size is on which the carb count is based. In cases where I have been able to look up chain restaurant food on the web, the portion sizes, if given, are often different from the actual sized portion you receive in the restaurant. So the counts, in this case, are meaningless.
Portion Size is Deceptive!
This points to another dangerous way that manufacturers can derail your diet. If you rely on the carb count you see on a label, without reality checking the portion size against the portion a normal person would eat, you'll get nasty surprises.
A case in point here is Dreamfields pasta. These products claims to magically remove about 50 grams of carbs per serving, though the full 50 grams of carbohydrate is
listed on the label. Those of us with diabetes who use blood sugar meters have found that Dreamfields' carbs digest so slowly that they don't register at 2 hours after eating, the time when the tests are often done on which the claim of "not raising blood sugar" is based.
But Dreamfields DOES raise blood sugar 5-12 hours later. If a person has normal insulin production, they may not see this rise as it is slow enough that their pancreases can keep up with producing the insulin needed to deal with it. But because those carbs do hit the blood stream insulin will rise. If you are low carbing for weight loss, keeping insulin low is important,these hidden carbs may well stall your loss.
But there's an even bigger problem with Dreamfields pasta, and that is that the portion size is 2 oz. To see why this is a problem, weigh out 2 ounces of dry pasta and boil it up.
Is the resulting amount what you would think of as a "portion?" No way! In fact, unless you are getting 8 servings out of the 16 ounce box of pasta, you are probably eating 2 or 3 times the 50 grams of carbs the labels list.
Portions on canned soups are similarly misleading. Have you ever gotten 2.5 servings from a can of Campbell's Soup? Me neither.
Hiding Carbs by Rounding
Sometimes the manufacturers hide carbs by citing a very small portion size because labeling law allows them to round down. This is very common with trans fats too, which is why you see a lot of labels where the amount of trans fat listed is "0" but the ingredient lists contains hydrogenated oils--a sure sign the food does contain trans fat.
With rounding, the company can claim 0 g of anything where there is less than 1 full gram.
This can really hurt you. For example, a cup of light cream has 7 grams of carbs, though the label may say 0 g based on a tablespoon portion size. Powdered artificial sweeteners contain about one half gram of sugar per teaspoon because they use maltodextrin, a form of glucose, to make them powdery. If you cook with a cup of powdered Splenda you will be getting about 24 grams of carbohydrate, which is what you'd find in six teaspoons of sugar.
So What Does This Mean for You?
If you are just starting out low carbing, you should treat any supposedly "low carb" product that cites net carbs rather than total carbs with great caution. If you are one of people who do metabolize sugar alcohols, these "low impact carbs" will turn into regular, old, high-impact glucose, and eating a couple of these treats each day can easily derail your low carb diet by adding another 20 to 40 grams of carbohydrate to your intake.
That's why you might be wise to try low carbing without any of these suspect foods for the first few weeks of your diet until you have become accustomed to how your body feels when your blood sugar has stabilized on a truly low carb regimen. If you crave a sweet treat during these first few weeks, try one of truly low carb treats and snacks whose recipes have been posted on web. You can find these recipes using Google Groups Advanced Search scanning the alt.support.diet.low-carb newsgroup for term "REC." You'll find hundreds of recipes containing no "hidden carbs" at all. Do this until you've gotten the hang of what low carbing feels like to your body.
Once you've gotten into a steady low carb regimen and are losing weight steadily, you can test these commercial "low carb" products to see what effect they have on you. If you keep losing weight after introducing them, you can relax. You are one of lucky ones who can, in fact, treat them as having "low impact" carbs. If you don't, well, for you there's no free lunch. Continue making your own truly low carb treats--and losing weight.
If you are diabetic, you don't have to guess about how sugar alcohols affect you. You can turn to your trusty blood sugar meter to see what they do to your blood sugar. But if you test, test products containing sugar alcohols 2 and 3 hours after eating. Testing only at one hour after eating may be too early and you may miss blood sugar spikes they cause. With the"low carb" pastas, you may have to test as many as 5 hours after eating and you should also look at your fasting blood sugar the next morning. Several people have reported that while they didn't spike on the low carb pastas, their fasting blood sugars were significantly elevated the next morning.
Watch Out for Increased Hunger
No matter what you see on your scale or observe on a blood sugar meter, be alert for an increase in your hunger level when you eat these "net carbs" foods. My own experience and that of some other low carb dieters who have reported this on the newsgroup is that some of "low carb" products made with sugar alcohols cause an increase in hunger that is out of proportion to the blood sugar readings they produce. I have found this especially noticeable with foods containing lacitol, including breath mints which claim to only contain one gram of sugar alcohol.
If you notice yourself suddenly getting hungry, or just plain eating more food after you have introduced a new "low carb" treat into your diet, back off it for a few days and see what happens to your hunger level. If it goes down, you'll need to treat these foods with caution. The whole point of low carbing is to eliminate the hunger cravings that make dieting so difficult.
Don't Forget the Extra Calories
Even if you can eat snack products containing sugar alcohols without experiencing blood sugar spikes or hunger cravings, it's worth giving some thought to the question of how good an idea it is to fill your diet up with calorie-dense low carb junk food.
Though the best selling diet book authors make it sound as if low carbing somehow magically "melts fat away" this is not true. Low carbing evens out blood sugar which eliminates hunger and makes it very easy to eat a lot less food. But to achieve long term weight loss you must eat less than you burn each day.
As you get closer to your weight goal, this becomes more and more evident. The smaller you are, the less food your body burns. As a result, most people find they cannot get last the 20 pounds off without watching their calories closely and eating only 9 - 10 times their body weight in calories. (i.e. if you weigh 140 lbs you may find you have to eat as little as 1269 to 1400 calories a day to lose, depending on speed of your metabolism and your activity level.)
With that in mind, you can see why, independent of the blood sugar issue, that snack bar with its 240 calories that you eat every day between meals may have serious repercussions for your diet--it is adding 1,680 calories a week--enough calories to create 1/2 pounds of fat--besides replacing more nutritious foods like the high fiber, low carb vegetables that are an important part of the diet of long-term successful low carb dieters.