Field of Science


The Shambulance: Zero-Calorie Noodles?

(The Shambulance is an occasional series in which I try to find the truth about overhyped health products. My Shambulance co-captains this week are Steven Swoap and Daniel Lynch, both of Williams College.)

It could almost be a Zen question: What do you call a food with no food in it? In Japan they're called shirataki noodles, and are made from the root of the konjac plant. In the United States they're called "Miracle Noodles" or a "healthier alternative to pasta" and promise "NO calories...NO net carbs...NO GUILT!!!"

The konjac root's contribution to the noodle is straight dietary fiber, in a form called glucomannan. Since the noodles are made of nothing but fiber and water, the idea goes, they'll hurry right through you without leaving any calories behind. This is attractive to American dieters who would like to be able to eat a whole plate of food without actually eating any food. A dinner of pasta topped with marinara sauce becomes a dinner of marinara sauce topped with time on the toilet.

The Chicago-based brand "NoOodles" displays a set of nutrition facts with zeros nearly all the way down, like a perfect report card. However, "Don't be mistaken," says Williams College physiologist Steven Swoap. "These noodles have calories!"

Insoluble fiber, Swoap explains, does pass through our bodies untouched and make up the bulk of our feces. But glucomannan is a soluble fiber. This means it's dissolvable in water; it's also digestible by the bacteria living in our guts. The bacteria break down soluble fiber into products that we absorb as calories. (They also make methane, which, as Swoap points out, "we don't absorb but rather share with our surroundings.")

The key to the zero-calorie claim made by NoOodles might lie in that 1.6-ounce serving size at the top of the label. The FDA permits calories under 5 to be rounded to 0. If each of those dainty servings really has 4 calories, a whole package—which would fill a plate—has about 20. It's hardly a calorie count that will ruin anyone's diet. But zero, in this case, doesn't really mean zero.

Shirataki noodles have a distinctly non-zero amount of offensive odor, as I discovered when I tried some NoOodles for myself. (They're in the refrigerator aisle, which I only mention in case you want to buy your own and also want to avoid having this conversation with two different grocery store clerks: "I'm looking for a product called noodles?")

The product's website describes the smell, caused by the calcium hydroxide, as "a little odd." I would have used different words, like maybe "neglected fish." But the odor rinses away with water. The rectangular shape of the package is harder to dispel.

I followed directions and heated my NoOodles in a dry nonstick pan until all the water had evaporated, though they looked otherwise the same. At this point it's recommended that you cook the NoOodles with some sort of sauce (or eggs or ice cream), but I wanted to try them in their unadulterated form. As promised, they tasted like nothing at all. They had a texture, though, that I was deeply not okay with, like biting through rubber bands. I managed one mouthful followed by a lot of water.

The water is recommended too, because soluble fiber sucks up water in your body. In 2010, Health Canada issued an advisory about the importance of drinking a full glass of water when taking pills or powders containing glucomannan. It also urged consumers not to use glucomannan supplements right before bed, because the stuff can swell up and cause choking or blockages in the intestine while you sleep. The health advisory didn't address shirataki noodles.

The water that NoOodles absorb makes the material passing through your gut especially slippery, so your small intestine can't absorb nutrients (which is to say, calories) as easily. Their website claims this makes the rest of your meal less caloric too, as everything slides through you along with the NoOodles. But Swoap says that experiments have shown this simply isn't true. "The small intestine is still long enough to get all of the calories from your food."

Among several other promises, NoOodles makers also say their product makes you feel fuller, so that "one tends to eat less when NoOodle is part of the meal." It's certainly possible, though it's also possible that one tends to make up those calories at one's next meal, when one is starving because one only ate marinara sauce for dinner. "The key word that gets them off the hook is 'tends,'" Swoap says. "Otherwise the FDA would have a major problem with this."

Not all the claims made about glucomannan noodles are spurious. The product does let dieters eat more food for fewer calories. And some studies have found that glucomannan can lower cholesterol, both in healthy and diabetic subjects.

So is an all-fiber noodle really a "healthier alternative?"

"The 'benefits' are in comparison to refined wheat flour that is used to make breads, pastas, etc. Most everyone acknowledges that is not good in excess," says Daniel Lynch, a biochemist who's also at Williams College. "But moderation is the key." He adds, "You might as well just have a glass of Metamucil or Citracel as a pre-dinner cocktail and then enjoy real food in smaller portions!"

Swoap says, "I don’t think this is necessarily bad for you. I would just prefer to get my fiber with vegetables that also bring along a lot of micronutrients." In other words, if you want to bulk up your meal with a low-calorie fiber source, there are less rubbery and more vitamin-filled ways to do it.

If you're still tempted to try a food-free plate of pasta, go for it. Just remember to drink water.

Arvill A, & Bodin L (1995). Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men. The American journal of clinical nutrition, 61 (3), 585-9 PMID: 7872224

Chen HL, Sheu WH, Tai TS, Liaw YP, & Chen YC (2003). Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects--a randomized double-blind trial. Journal of the American College of Nutrition, 22 (1), 36-42 PMID: 12569112

Thanks to Chris F. for the tip! If you want to summon the Shambulance to the site of an emergency, leave a comment or send me an email at the address above.


  1. The shirataki noodle packages I buy (not the same brand) are always in bags filled with liquid. Doesn't this saturate the fiber?

    Just because a dried powder or pill warrants warnings and advisories about drinking water or choking hazard, hardly means the same goes for a water saturated foodstuff.

    Sure, they don't taste like much -- but the taste of noodles dishes is all about the sauce. Standard refined noodles are just bland starch. Sure you could eat spaghetti and vegetables for fiber, but you can eat shirataki and vegetables just as easy.

  2. I actually find the taste of Konjac noodles to be quite agreeable. I'm not familiar with the brands you mention, but the noodles I get from the Asian grocers are really quite good when drenched with some nice sauce or other. They are more 'noodley' than pasta, but I prefer it, particularly as I don't eat wheat pasta due to the ridiculous amount of high GI carbohydrate contained in it.

  3. This article is certainly NOT well-informed. Get some facts next time, eh?
    1. Konjac powder is a very hydrophyllic food ingredient, and there have been choking deaths caused by consuming the unhydrated gum. But shirataki noodle is a completely safe food - confirmed by millions of Japanese.
    2. Foods high in insoluble fiber reduce cholesterol (hinder absorption of bile acids), post prandial blood sugar (decrease rate of sugar absorption), blood pressure (fermentation by probiotic bacteria to short-chain fatty acids), colon cancer risk (reduced transit time in the digestive tract), and appetite for MORE FOOD (swells in the gut). Same as oatmeal.
    3. American diets are undersupplied with fiber, and soluble fiber is particularly lacking. FDA recommends 25 grams fiber/day (= 8 apples).
    4. FDA applies basic rounding principle to allow a zero calorie label statement (less than 5 rounds down to zero). So promoting a 20-cal plateful of food is somehow deceitful to consumers? Really?
    5. Had you wanted to provide useful advice regarding shirataki noodles, why not mention that sources commonly sold in Asian markets are much cheaper, compared with new brands marketed as "health foods"?
    6. Finally, you obviously had some fun comparing the noodles in their most basic state - without sauce or condiment to improve palatability - to "rubber bands" or "a glass of metamucil". But a more thoughtful writer would have consulted an expert in the use of the product - Japanese chef perhaps - who knows how to present the food to best advantage.

    Good that this valuable alternative to high carb pasta gets some mention, but your contribution was nothing, really, to be all that proud of.

    1. " So promoting a 20-cal plateful of food is somehow deceitful to consumers? Really? "

      Promoting it as having zero calories, is, yes. Duh.

    2. It's basic mathematics. Anything less than four rounds down to zero, anything between five-nine rounds to ten. All food manufacturers do it. Have you ever seen a label that lists their product as having 14 calories, or 96, or 311? No, it's called rounded. There is nothing deceitful if it is a well-known fact that ALL food manufacturers do it.

  4. Anonymous #2 here again.
    Sorry, I note a typo in item 2 which should read "Foods high in soluble fiber...". Insoluble fiber, while important, mainly adds bulk to the stool, though there are also important soluble phenolics in most brans.

    Also, veteran legman to the core, I reconfirmed the tech lit regards various positive physiologic responses to soluble fiber in the diet. And frankly I'm surprised your two academic "co-captains" didn't have more relevant info to offer on these issues.

    Finally, if the purpose of your column is "to find the truth about overhyped health products" I'd say you were off-message here. Looking for overhyped items, shirataki noodle is a poor candidate.

    Maybe better stick to kid science.

  5. Their claims about reducing the total caloric absorption of the nutrients is probably in comparison to taking a nutritional meal replacement shake, which is absolutely true (and is a fact that can be well exploited when dealing with people who can't seem to lose fat while consuming those things).

    It's just not relevant when you're comparing Real Food to Real Food With Shirataki Noodles.

  6. Max and The DieteersDecember 14, 2012 at 3:52 PM


    Your condescension is irritating. Please shut up. Thanks.

  7. I think that in an industrialized world where states spend billions because of obesity, where half of all adults and a third of kids are overweight, noodles with 20 calories per serving represent a great opportunity for fighting obesity. I'm sure that there are many that have been struggling with weight problems for ages that would gladly overlook a rubbery texture in order to shed some pounds. The fact that you can store them and cook them with any vegetable or meat sauce makes them very appealing.

  8. As for the 20 calorie claims... you realize that even somebody on a seriously low caloric intake range of 1100-1300 a day still have to get their calories from somewhere, right?


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