Low Carb Snacks - Are the Net Carbs Accurate?

I am trying to keep to a low carbohydrate diet. Are the various snacks and “power bars” which advertise as having three or four “net” carbs the real deal? Or are they pulling the wool over my eyes?

Aside from the fact that many people consider the low carb thing to be a marketing fad, I can tell you that the FDA is able to permit a number of exceptions to the labeling guidelines. A good example is the product Nutra-Sweet. If you look at a packet, you’ll see that the first ingredient listed is sugar. In fact, a one gram packet contains about one gram of sugar. (it also contains a tiny amount of a powerful sweetener. The sugar is there as a vehicle.) But it is also listed as a zero calorie material. This is because the FDA permits items that contain about one gram to claim that there are NO calories associated with it. Now, we know that sugar contains about four calories per gram, so whatever “net calories” are, there may be a considerable amount of fudging involved. Just sayin’ xo C.

I’m sitting here looking at a Pria bar, and here’s the manufacturer’s breakdown:

Total carbs: 21 g
Fiber: 2 g
Sugar alcohols (things like malitol, which you find in sugarless gum): 17 g
Net carbs: 2 g

For a low-carb diet, the idea is that what is important is the grams of carbs that impact blood sugar. A biochemist or biologist (or someone, anyway) should be able to either confirm or refute that fiber and sugar alcohols do not have any effect on blood sugar. It does not mean that there are only 2 g of carbs, there are still 21 grams, but that only 2 grams of the stuff actually hits the bloodstream. Or something like that.

Atkins says: the measurement of net carbs is an ongoing development.

Just a reminder, but if you are just starting out, it is best to stay away from all those prepared foods. Eat whole veggies or a chunk of cheese or a handful of nuts for snacks and you’ll be a)a lot less confused b)more on track to sucess. (Oftentimes poeple replace old bad habits with new bad habits with those bars and convenience foods. Atkins is about eating whole, fresh foods.) Ahem, carry on.

Atkins Advantage bars and Atkins Breakfast Bars fit all steps of the Atkins Nutritonal Approach. They are good choices — low carbs, and nutritional.

Yes, but you shouldn’t rely mostly on those. They should be used as quick meals when it is not possible to get something else.

IANAB, but from what I read this “net carbs” is a gimmick by the Atkins people. Sugar alcohols do have an effect on blood sugar. What your label says is that it doesn’t and that the fiber prevents all but 2 grams to affect blood sugar. Fiber slows down digestion but not does not prevent it. Your Pria bar actually contains 38 grams of sugar, 17 in the form of sugar alcohols.

barbitu8, the sugar alcohols are a subset of carbohydrates, so even if you did want to count them instead of disregarding them for the “net carbs” purposes, the total carbohydrates in the example Pria bar is still 21. The 21 grams is 2 g of fiber, 17 of sugar alcohols and 2 grams of other (sugar).

As for whether the “net carbs” method of counting is sound, I have only anecdotal evidence. I used to read the lowcarb Usenet newsgroup quite a bit, and one of the women there was an insulin dependent diabetic. She decided to measure her blood sugar at intervals after eating various “low carb” meal replacement bars, and her findings were that although these bars (and the Atkins site itself) claim that sugar alcohols and glycerine don’t affect blood sugar and therefore don’t need to be counted for low carb dieting purposes, for her, eating a low carb bar that touted low “net carbs” raised her blood sugar almost exactly as a plain old Hershey bar did.

Take that as you will.

IANAD, IANYD, talk to your doctor before starting any diet to determine which program would be best for you.

The difference here is between the chemical definiton of carbohydrates and a significantly less scientific version that the low-carbohydrate diets are trying to push.

All carbohydrates, from the common sweeteners sucrose and fructose (sugar), to lactose (milk sugar), amylose (starch), cellulose (fiber) and glycogen, have a basic structure that is similar enough that they belong to the same class of molecules. There is, however, a tremendous difference in the way that your body uses them.

Sucrose and Fructose have two 5- or 6-carbon units connected together by an alpha linkage, which is determined by the orientation of carbon and oxygen atoms about the linkage. An alpha linkage is trivial to break down by the adult human body, and this frees up the 5- or 6- carbon units to be used by your body, which also happens readily.

You could also have a different orientation called a beta linkage. Chemically it’s the same as an alpha linkage, but the orientation of the units is rotated about an axis. Your body generally cannot break down a beta linkage on its own. Lactose, a 2-carbohydrate beta linked molecule, is not easily broken down by your body, and instead can be broken down by the microorganisms living in your gut, producing lactic acid and methane. Not too good. Generally speaking, humans do not have the chemical catalysts necessary to use beta linked carbohydrates effectively for energy.

There are some molecules that are long chains of alpha linkages. They’re effectively used to store energy, both by you, and also by plants. This is the energy that’s being stored in a potato, for example. These can be broken down into single sugars; it’s why starch increases your blood sugar.

Other molecules are made of long chains of beta linkages. In terms of human energy metabolism, this is useless. They are the same long chains of the same simple sugars that *could *raise your blood sugar, but they were stored by the plant in a way that you cannot break chemically. This is called dietary fiber. It stays in your GI tract, where it has numerous chemically complicated effects, some of which are very important. But they’re *not *broken down into simple sugars, and they’re *not *used by your body for energy.

So dietary fiber is important for nutrition and health, and it’s also a form of carbohydrate. But in terms of diets that concentrate on reducing carbohydrates, you could effectively ignore them.

Though anectdotal, that is exactly the kind of info I was looking for. Thanks.

I have a decent layman’s understanding of dietary fiber and from what I have read, your last statement is accurate. What’s the deal with sugar alcohols?

At this hour, the best that I can tell is that they’re normal sugars which have been chemically modified (though some are natural, it would be safe to assume most are synthetic) to change the rate of absorption in the intestine, and to have a reduced effect on insulin and glucagon response. They are carbohydrates, and they do have calories, but the gimick in the Atkins diet is not reducing carbohydrates per se, but instead to reduce intake of carbohydrates that stimulate an insulin response. It seems that totally removing sugar alcohols from the equation involves quite a bit of hand waving and bad science.

Then again, few people claim that low carbohydrate diets are good science. The real trick is regular cardiovascular exercise and calorie management, and always has been.

Livesey, G., “Health Potential of Polyols as Sugar Replacers, with Emphasis on Low Glycaemic Properties,” Nutrition Research Reviews, 16(2), 2003, pages 163-191.

Um, the “gimmick” in the Atkins diet is to drastically reduce carbohydrates. After a while, you can slowly add them back, but only the good kind.


Haven’t read the book, I see.

Volek, J.S., Westman, E.C., “Very-Low-Carbohydrate Weight-Loss Diets Revisited,” Cleveland Clinic Journal of Medicine, 69(11), 2002, pages 849-862.

Brehm, B.J., Seeley, R.J., Daniels, S.R., et al., “A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women,” The Journal of Clinical Endocrinology and Metabolism, 88(4), 2003, pages 1617-1623.

Dashti, H.M., Mathew, C.M., Hussein, T., et al., “Long Term Effects of a Ketogenic Diet in Obese Patients,” Clinical Cardiology, 9(3), 2004, pages 200-205.

Yancy, W.S., Jr., Olsen, M.K., Guyton, J.R., et al., “A Low-Carbohydrate, Ketogenic Diet Versus a Low-Fat Diet to Treat Obesity and Hyperlipidemia,” Annals of Internal Medicine, 140(10), 2004, pages 769-777.

The studies done for six months indicated that the low carb diet did best, but more recent studies have been done for a year which have been contra.