Super Fiber

T Nation: Mike, I've been hearing more and more about glucomannan lately. Is it just another scam supplement or does it really work?

A: The popularity of glucomannan has definitely been increasing and I expect it to continue to become more and more popular as the research behind it continues to grow.

Glucomannan is basically a soluble super fiber. It comes from the root of the konjac plant and you can buy it as a powder or in the noodle form.

When you take a glucomannan supplement, the powder has the ability to almost instantly turn liquid into a thick gel. Only a video can truly do it justice:

Now just imagine that happening in your stomach! Taking a glucomannan supplement will help slow the release of food from your stomach and through your GI track by greatly increasing the food's viscosity.

This is a fat loss dieting dream. Because the glucomannan decreases the rate in which food leaves your stomach, your stomach will remain fuller longer(1) and on less food. This means that you won't be so miserable when eating less.

Because glucomannan is slowing the rate in which food leaves your stomach, this means that it's also slowing the rate in which carbohydrates leave your stomach and thus the rate in which they enter your blood stream. Better blood sugar control means faster fat loss and better health.

That sounds all well and good, right? But what does the research say about glucomannan? Preliminary data from a study conducted in diabetics showed the 1 gram of glucomannan given 30 minutes before an Oral Glucose Tolerance test (drinking 75g sugar beverage and then measuring blood sugar levels for 2 hours) yielded a significant blunting effect on blood sugar levels (3% vs. 12% increase in blood sugar levels between hours 1-2).

That was just one small study from Thailand. Let's look at some other research.

As you may have expected, studies have shown that the incorporation of glucomannan into a weight loss diet does elicit a greater amount of weight loss(1-4), but it should be noted that in some cases the subjects weren't given instructions to restrict their calories.(4)

Dr. William Kraemer (the godfather of strength & conditioning research) headed up a recently published study that investigated the interaction or added effect of glucomannan and exercise.(5) This study did not show a synergistic effect between exercise and glucomannan, but the additive effect of the exercise and glucomannan together may have been more apparent if there would have been a control group that did not receive glucomannan or exercise.

We'll just have to wait for some more research in that area.

Aside from helping people lose weight, control blood sugar, and feel fuller, glucomannan also has been shown to have significant effects on cholesterol levels, consistently lowering LDL cholesterol and total cholesterol levels.

In the mainstream nutritional science community, one of the biggest criticisms of very low carbohydrate diets is their inability to decrease LDL cholesterol (often touted as the "bad" cholesterol). Another study from the Kraemer crew showed that the addition of glucomannan to a very low carbohydrate diet dropped LDL cholesterol levels by 14%.

One common complaint that many first time low carbers have with the diet is the constipation commonly associated with the decreased carbohydrate/fiber intake of very low carb diets. While this often goes away, it is still... uncomfortable. This is another area where glucomannan can help as it can help relieve constipation(6, 7)and increase the transit time of waste through your body.(8)

Glucomannan isn't perfect as there can be some negative side effects. It was effectively used in a 2007 study to successfully reduce thyroid hormone levels (T3 & T4) in hyperthyroid individuals.(9) The exact mechanism by which glucomannan was able to decrease T3/T4 levels is not completely understood. There's also no evidence to suggest that thyroid hormone levels would be affected in normal individuals.

Other side effects of glucomannan do include: abdominal pain, lower GI obstruction, and increased flatulence.

Glucomannan can be hard to find in stores and my experience has been that when you do find it, it's way over priced. You can get it here for less then $10.

Start by taking 3 grams a day. You can take the capsules straight, but I recommend actually using glucomannan in your cooking. Many dishes and sauces are usually thickened with flour or butter, but these techniques can add unnecessary starches or fats to your meal plan. As shown in the video, glucomannan is a great thickening agent and so I recommend you use it to thicken your next stir fry or batch of chili.

Too Sensitive to HOT-ROX Extreme

T Nation: My body is very sensitive to HOT-ROX Extreme and I can only take 1 capsule at a time. Is there anything else that I can do supplement-wise to maximize my fat loss?

A: Good question. I too am sensitive to the yohimbine HCl/caffeine combination found in HOT-ROX Extreme and can usually only take one capsule at a time. There are some things you can do to still get the maximum effect from your supplementation, though.

Hot-Rox® Extreme also contains Carbolin-19®. When taken straight you can take 2 capsules of Carbolin-19 twice a day. Because you are only going to take half the HOT-ROX Extreme dosage, you can augment this with half a dosage of Carbolin-19. So in the morning you would take 1 HOT-ROX Extreme and 1 Carbolin-19 and then repeat this in the afternoon.

You can use this same theme a couple different ways depending on your sensitivity to the stimulants in HOT-ROX Extreme. If you can handle a full dosage of HOT-ROX Extreme in the morning but not later in the day (because it would keep you up at night), then do the following:

Morning: 2 Hot-Rox® Extreme

Afternoon/Evening: 1 Hot-Rox® Extreme plus 1 Carbolin-19®, or No Hot-Rox® Extreme and 2 Carbolin-19® caps.

Other supplements you can add to these stacks include Green Tea Extract and CLA, neither of which are stimulants but still can have positive effects on weight loss.


  1. Cairella M, Marchini G. [Evaluation of the action of glucomannan on metabolic parameters and on the sensation of satiation in overweight and obese patients]. Clin Ter1995; 146: 269-274.
  2. Livieri C, Novazi F, Lorini R. [The use of highly purified glucomannan-based fibers in childhood obesity]. Pediatr Med Chir 1992; 14: 195-198.
  3. Vita PM, Restelli A, Caspani P, Klinger R. [Chronic use of glucomannan in the dietary treatment of severe obesity]. Minerva Med 1992; 83: 135-139.
  4. Walsh DE, Yaghoubian V, Behforooz A. Effect of glucomannan on obese patients: a clinical study. Int J Obes 1984; 8: 289-293.
  5. Kraemer WJ, Vingren JL, Silvestre R, Spiering BA, Hatfield DL, Ho JY, et al. Effect of adding exercise to a diet containing glucomannan. Metabolism 2007; 56: 1149-1158.
  6. Loening-Baucke V, Miele E, Staiano A. Fiber (Glucomannan) Is Beneficial in the Treatment of Childhood Constipation. Pediatrics 2004; 113: e259-264.
  7. Chen H-L, Cheng H-C, Liu Y-J, Liu S-Y, Wu W-T. Konjac acts as a natural laxative by increasing stool bulk and improving colonic ecology in healthy adults. Nutrition2006; 22: 1112-1119.
  8. Marzio L, Del Bianco R, Donne MD, Pieramico O, Cuccurullo F. Mouth-to-cecum transit time in patients affected by chronic constipation: effect of glucomannan. Am J Gastroenterol1989; 84: 888-891.
  9. Azezli AD, Bayraktaroglu T, Orhan Y. The Use of Konjac Glucomannan to Lower Serum Thyroid Hormones in Hyperthyroidism. J Am Coll Nutr 2007; 26: 663-668.