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Original Research
Konjac Glucomannan Dietary Supplementation
Causes Significant Fat Loss in Compliant Overweight
Adults
Gilbert R. Kaats, PhD, Debasis Bagchi, PhD, Harry G. Preuss, MD
Integrative Health Technologies, Inc., San Antonio, Texas (G.R.K.); Department of Pharmacy, University of Houston, Houston,
Texas (D.B.); Department of Biochemistry, Georgetown University Medical Center, Washington, DC (H.G.P.)
Key words: glucomannan, weight loss, compliance, fat loss
Objectives: Changes in body composition and blood chemistries between overweight adult subjects
receiving a supplement containing either 3 g of konjac glucomannan/300 mg calcium carbonate or a placebo
containing only 300 mg of calcium carbonate were compared as the primary objective. A secondary objective
was to compare outcome differences between compliant and partially compliant subjects.
Methods: A total of 83 overweight adults (66 women and 17 men) completed a randomized, double-blind,
placebo-controlled protocol in which they received either a glucomannan or placebo supplement for 60 days.
Dual-energy x-ray absorptiometry (DEXA) total body scans and a 42-measurement blood test were completed at
baseline and 60 days later. Compliance was assessed by rating self-reports of (1) how many tablets were taken,
(2) adherence to taking the tablets 30 minutes before eating, and (3) a sum of the ratings for (1) and (2). An
anonymous poststudy questionnaire and telephone calls were also completed by 80 (96%) of the participants
who were used as the study cohort.
Results: No statistically significant differences were found between the groups on changes from baseline on
the DEXA and blood tests. However, when subjects were classified as either compliant or partially compliant
using the compliance measures, statistically significant reductions in scale weight, percentage body fat, fat mass,
total cholesterol, and low-density lipoprotein (LDL) cholesterol were found in the glucomannan group
compared to the placebo group.
Conclusions: This study supports the efficacy glucomannan supplementation to reduce body weight, body
fat, and circulating cholesterol levels without the concomitant loss of lean mass and bone density often
associated with weight loss. However, these positive outcomes were not observable until corrections for
compliance were applied.
INTRODUCTION
A growing body of evidence suggests that accumulation of
excess body fat predisposes to diabetes mellitus, coronary artery
disease, stroke, sleep apnea, degenerative joint disease, and cer-
tain forms of cancer [1–4]. Unfortunately, with few exceptions,
no significant changes in the alarming prevalence of obesity
in youth or adults between 2003–2004 and 2011–2012 have
occurred [5,6].
Obviously, treatment options are uncertain. Other than bar-
iatric surgery [7,8], no pharmacologic or behavioral weight
loss treatments are consistently associated with large sus-
tained weight losses. A number of studies have shown that
pharmacological approaches are usually time-limited due to
the potential for serious side effects [9–13]. On the other
hand, dietary supplements to treat obesity have rarely been
accompanied by serious adverse effects [14]. However, there
is often insufficient evidence of their efficacy [14]. Suffice it
to say, there is a valid need to carry out well-planned clinical
trials examining the effectiveness of safe, natural dietary
ingredients to change body composition in a healthful direc-
tion—loss of excess fat mass with retention or even gain in
fat-free mass (FFM; representing muscle) and bone mineral
density (BMD) [15].
The primary purpose of this investigation was to determine
whether dietary supplementation with the fiber glucomannan
induces significant fat loss. A recent meta-analysis on the sub-
ject failed to reveal such [16]. In the present study,
Address correspondence to: Gilbert Kaats, PhD, Integrative Health Technologies, Inc., 5170 Broadway, Suite 5, San Antonio, TX 78209. E-mail: grk@ihtglobal.com
1
Journal of the American College of Nutrition, Vol. 0, No. 0, 1–7 (2015) ÓAmerican College of Nutrition
Published by Taylor & Francis Group, LLC
glucomannan produced major fat loss with virtually no major
loss of muscle and bone density only when the fiber was taken
as directed; that is, the patients were compliant to directions.
This new observation could explain the divergent results often
found in weight loss studies involving glucomannan and per-
haps other dietary supplements [16].
METHODS
Design
This study used a randomized, double-blind, placebo-con-
trolled protocol and was conducted during a holiday season;
that is, from October through December. The Institutional
Review Board at Texas Women’s University approved the
study, and all study participants signed informed consent that
asked them to obtain approval from their personal physicians
or health care providers to ensure that they had no medical con-
ditions that would preclude their participation. Notwithstand-
ing this approval, pregnant or lactating women were excluded
from participation. A total of 83 study participants, 66 women
and 17 men, completed the study.
Enrollment and Payment of Incentives
Other than pregnancy and requiring permission from their
family physicians, few restrictions were placed on enrolling
subjects in order to recruit a study sample that would most
likely represent the end users of the product being evaluated.
At the conclusion of the study, each subject was provided com-
prehensive reports of their baseline and ending blood chemistry
profile and dual-energy x-ray absorptiometry (DEXA) tests.
Subjects were told that if they completed a product-usage
record for each day of the study and completed the ending
tests, a $200 contribution would be made in their name to a
nonprofit organization of the subject’s choosing. Subjects were
repeatedly advised that this fee would be paid irrespective of
how few or how many tablets the subject consumed each day,
including “0” usage, as long as they completed the end-of-
study tests. They were also advised that the purpose of this pro-
cedure was to encourage candid reporting so we could obtain
“dose-related” data.
Correcting for Compliance
After finishing all ending tests, participants were asked to
complete an anonymous critique of the study that, among other
items, asked how closely they followed the research protocol;
that is, how many tablets were actually taken each day and the
timing of intake irrespective of what they had reported during
weekly check-ins. When receiving the questionnaire, partici-
pants were told not to sign it and to be candid about reporting
how accurately they revealed the information on their weekly
tracking forms. They were then asked to place the completed
questionnaire in an envelope, seal it, and give it to a research
technician. Upon receipt of the envelope, the technician
explained the importance of obtaining accurate data about
product usage and asked the participant if he or she would put
his or her name on the envelope if given a signed statement
insuring confidentiality and that the critique data would be
used for research purposes only. A total of 80 subjects (96%)
signed the envelope. A flowchart depicting these events is
shown in Fig. 1. Additionally, after all participation incentives
were paid to the subjects, research technicians contacted the
subjects by telephone to confirm the data in the ending ques-
tionnaire and determine how closely each subject complied
with the 30-minute premeal dosing (minutes) and the actual
number of the required 6 capsules they took each day (#capsu-
les). This allowed for 3 classifications of study compliance
among the active and placebo groups: (1) those who took
the supplement roughly 30 minutes before eating (minutes),
(2) those who reported taking 6 capsules a day (#capsules), and
Figure 1. Flow diagram of subjects through study.
Glucomannan and Body Composition
2 VOL. 0, NO. 0
(3) those who complied with both requirements of taking 6
capsules a day 30 minutes before a meal (both). Noncompliant
subjects were those who did not comply with these require-
ments at least 80% of the time.
Dietary Supplement
The dietary supplement used in this study (Propylene TM,
Natural Alternatives International, Inc., San Marcos, CA) pro-
vided subjects with daily amounts of 3 g of glucomannan solu-
ble fiber and 300 mg of calcium. After the blinding code was
broken at the conclusion of the study, 3 bottles of the active
and placebo products were randomly selected and subsequently
sent to an independent laboratory (Food Products Laboratory,
Inc., Portland, OR) to confirm the nutritional content of each.
These laboratory analyses confirmed the fiber and calcium con-
tents of the tested product and the absence of these ingredients
in the placebo.
Tests and Assessments
Study participants completed baseline and ending scale
weights using a strain-gauge scale (FS-0900, Befour Scale
Company, Inc., Saukville, WI) accurate to within §0.1 lb for
up to 400 lb. In addition to completing baseline and ending
vital signs, study participants completed a lunar total DEXA,
a 42-measurement blood test, and a self-report quality of life
inventory (QOL).
At the conclusion of the study, a body composition
improvement (BCI) index was calculated for each subject.
The BCI is based on scoring losses of fat and gains in FFM
in pounds as positive outcomes, and gains of fat and losses of
FFM are scored as negative treatment outcomes The BCI is
the net score from making these calculations.
Statistical Analyses
Calculation were made for 3 measures of compliance—
minutes, #capsules, and both. Minutes was defined as the
average time the capsules were taken prior to eating. The
#capsules was defined as the number of capsules the subjects
took. “Both” was the average of these two scores, The per-
centage of subjects complying with minutes, #capsules, and
both was contrasted by treatment group using a logistic
regression model. An interaction model was fit to assess the
significance of variation in the association between compli-
ance to minutes in the treatment and placebo groups with lev-
els of compliance to #capsules. Subjects who complied to
minutes were contrasted to those who did not comply to
minutes on mean age and mean baseline weight, percentage
body fat, FFM, and BMD using analysis of covariance on the
combined cohort; this analysis was repeated with restriction
to the active treatment group and with restriction to the pla-
cebo group. This series was repeated for compliance to
#capsules and for compliance to both. Analyses of changes
proceeded in 3 steps. First, interaction models were fit to
assess the significance of variation in the relation between
compliance to minutes (and separately to #capsules and both)
and active treatment group on mean changes in scale weight,
percentage body fat, fat, FFM, BCI, and BMD. Second, treat-
ment groups were contrasted with regard to mean changes in
these 6 outcome variables with restriction to subjects who
complied with minutes, complied with #capsules, and com-
plied with both. Contrasts of active treatment group means on
these 6 outcomes without accounting for compliance were
presented for reference. Third, subjects who complied to
minutes were contrasted to those who did not on mean
changes in the same 6 outcome variables with restriction to
the active treatment group; this analysis was repeated for
compliance to #capsules and for compliance to both. These 3
series of within-group contrasts were repeated with restriction
to the placebo group. All statistical testing was 2-sided and
was carried out with a significance level of 5%. Contrasts or
interactions with p-values less than or equal to 0.05 were
called statistically significant. All analyses were carried out
with SAS software (version 8.2, SAS, Cary, NC).
RESULTS
Comparisons of baseline values for the treatment and pla-
cebo groups are shown in Table 1 and reveal that there were
no statistical differences between the 2 study groups in these
variables.
As shown in Table 2, prior to adjusting for compliance,
there were no statistically significant differences between the 2
groups at the end of study.
The percentages of subjects in each of the 3 compliant
categories for the active treatment and placebo groups are
shown in Table 3. There were no statistically significant
differences between the 2 groups in the percentage of subjects
who complied with minutes, #capsules, or both. A cross-com-
parison between minutes and #capsules in both active treat-
ment and placebo groups revealed that compliance was
Table 1. Average Baseline Values between Treatment and Pla-
cebo Groups
a
Parameter Active (38) Placebo (42) p
Age (years) 47.9 §3.1 47.0 §3.0 NS
Weight (lb) 176.4 §10.2 179.0 §8.2 NS
Body fat (%) 41 §2.0 39 §2.0 NS
Fat mass (lb) 72.4 §6.3 69.5 §5.3 NS
FFM (lb) 103.9 §4.7 109.5 §5.4 NS
BMD (g/cm
2
) 1.21 §0.02 1.23 §0.03 NS
NS Dnot significant, FFM Dfat-free mass, BMD Dbone mineral density.
a
Averages §standard errors of the mean are depicted. Number of subjects in
each group indicated in parentheses.
Glucomannan and Body Composition
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION 3
greater in both groups with #capsules compared to minutes,
but these differences were not statistically significant in either
group. These data reveal that the percentages of subjects
complying with minutes, #capsules, or both were statistically
identical in both the active and placebo groups.
Table 4 presents the mean differences between the treat-
ment group’s compliers and noncompliers for each of the 3
compliance categories. Compared to noncompliers, those who
complied with the minutes requirement had significant reduc-
tions in body weight (p<0.001), percentage fat (p<0.001),
and fat mass (p<0.001) and a significant and beneficial
increase in their BCI (pD0.02). Compared to noncompliers,
those who complied with the #capsules requirement experi-
enced a significant reduction in body fat (pD0.04). Compared
to noncompliers, those who complied with both of the compli-
ance requirements had significant reductions in scale weight
(p<0.001), percentage fat (pD0.003), and body fat (pD
0.003) and had a significant and beneficial improvement in
their BCI (pD0.03). There were no significant differences
between compliers and noncompliers on mean changes in FFM
(pD0.24) or BMD (pD0.92).
As shown in Table 5, in contrast to the treatment group, the
placebo group showed no significant differences between com-
pliers and noncompliers in any of the 3 compliance catego-
ries—minutes, #capsules, or both.
Restriction to subjects compliant to minutes (Table 6)
revealed a significant and beneficial mean decrease in scale
weight (p<0.001), percentage body fat (pD0.007), and fat
(p<0.001) in the active treatment group relative to the pla-
cebo group and no significant difference between the active
treatment and placebo groups with regard to mean changes in
FFM, BCI, and BMD (p>0.05 for all).
Comparison of subjects compliant to #capsules revealed a
significant and beneficial mean decrease in percentage body
fat (pD0.05) and fat in the active treatment group relative to
the placebo group (pD0.05). There were no significant dif-
ferences between groups with regard to mean changes in scale
weight (pD0.19), FFM (pD0.63), BCI (pD0.09), or BMI
(pD0.47).
Comparison of subjects compliant to both revealed a signif-
icant benefit to the active treatment group for mean changes in
scale weight (p<0.001), percentage body fat (pD0.01), and
fat (pD0.003). There was no significant difference between
groups in the active treatment and placebo groups with
regard to changes in FFM (pD0.33), BCI (pD0.15), or BMI
(pD0.38).
Blood Chemistries
Comparisons were also made between changes from base-
line in the 42 blood chemistries for both groups (data not
Table 3. Comparisons of Percentages of Compliant Subjects in
Active Treatment and Placebo Groups
Group NMinutes #Capsules Both
Active 38 19 (50.0%) 25 (65.8%) 16 (42.1%)
Placebo 42 22 (52.4%) 32 (76.2%) 18 (42.9%)
Table 4. Average Changes (Delta) after 2 Months on Protocol
between Compliant and Noncompliant Treatment Groups
Active
Minutes
Parameter Compliant (19) Noncompliant (19) A-P
a
p
Weight (lb) ¡2.87 §0.85 3.97 §0.80 ¡6.84 <0.001
Body fat (%) ¡0.83 §0.34 0.87 §0.31 ¡1.70 0.007
Fat mass (lb) ¡2.49 §0.76 2.81 §0.64 ¡5.30 <0.001
FFM (lb) ¡0.38 §0.73 1.17 §0.67 ¡1.55 0.11
BCI (lb) 2.11 §1.22 ¡1.64 §1.04 3.75 0.02
BMD (g/cm
2
)¡0.36 §0.46 ¡0.83 §0.51 0.47 0.52
#Capsules
Parameter Compliant (25) Noncompliant (13) A-P p
Weight (lb) ¡0.48 §0.95 2.53 §1.31 ¡3.01 0.07
Body fat (%) ¡0.23 §0.30 0.50 §0.42 ¡0.73 0.17
Fat mass (lb) ¡0.76 §0.74 1.92 §1.02 ¡2.68 0.04
FFM (lb) 0.28 §0.68 0.61 §0.84 ¡0.33 0.75
BCI (lb) 1.04 §0.96 ¡1.31 §0.1.33 2.35 0.16
BMD (g/cm
2
)¡0.56 §0.45 ¡0.65 §0.62 0.09 0.90
Both
Parameter Compliant (16) Noncompliant (22) A-P p
Weight (lb) ¡2.75 §1.00 2.95 §0.86 ¡5.70 <0.001
Body fat (%) ¡0.81 §0.34 0.63 §0.29 ¡1.44 <0.003
Fat mass (lb) ¡2.47 §0.79 2.07 §0.67 ¡4.54 <0.001
FFM (lb) ¡0.28 §0.74 0.88 §0.63 ¡1.16 0.24
BCI (lb) 2.19 §1.15 ¡1.19 §0.98 3.38 0.03
BMD (g/cm
2
)¡0.64 §0.56 ¡0.56 §0.47 ¡0.08 0.92
FFM Dfat-free mass, BCI Dbody composition improvement, BMD Dbone
mineral density.
a
Change from baseline and study completion, defined as the value at the last visit
minus baseline (for weight and fat changes, negative values indicate benefit,
whereas the opposite pertains to FFM, BMD, and BCI).
Table 2. Comparison of Average Changes between Treatment
and Placebo Groups without Adjusting for Compliance
Parameter Active (38) Placebo (42) A-P
a
p
Weight (lb) 0.55 §0.77 1.21 §0.73 ¡0.66 0.53
Body fat (%) 0.02 §0.27 0.53 §0.25 ¡0.51 0.18
Fat mass (lb) 0.16 §0.63 1.10 §0.60 ¡0.94 0.28
FFM (lb) 0.39 §0.52 0.11 §0.50 0.28 0.70
BCI (lb)
b
0.23 §0.86 ¡0.99 §0.82 1.22 0.31
BMD (g/cm
2
)¡0.59 §0.33 ¡0.14 §0.31 ¡0.45 0.32
FFM Dfat-free mass, BCI Dbody composition improvement, BMD Dbone
mineral density.
a
Change from baseline and study completion, defined as the value at the last visit
minus baseline (for weight and fat changes, negative values indicate benefit,
whereas the opposite pertains to FFM, BMD, and BCI).
b
The BCI is based on scoring losses of fat or gains in lean as positive outcomes,
whereas gains of fat or losses of lean are scored negatively. By adding a particu-
lar person’s positives and negatives, the BCI is obtained (see Methods for more
details).
4 VOL. 0, NO. 0
Glucomannan and Body Composition
shown). Although there were no baseline differences between
the active treatment and placebo groups in total cholesterol
(TC) and low-density lipoprotein (LDL) cholesterol, a com-
parison of cholesterol changes occurring in the 2 groups
revealed a significantly greater reduction in TC (¡13.9, p<
0.008) and in LDL cholesterol (¡13.7, p<0.005) in the
treatment group compared to the placebo group. Both groups
were further stratified into 3 subgroups using baseline total
cholesterol levels of high >200, acceptable D151–199, and
low <151. In the active treatment group, subjects with high
cholesterol had a statistically significant reduction in both
total and LDL cholesterol. Those with acceptable levels
remained unchanged and those with low levels increased their
cholesterol levels, although the latter failed to reach statistical
significance. In contrast, there were no significant reductions
in cholesterol or LDL levels in the high cholesterol placebo
group, nor were any significant changes were found in high-
density lipoprotein, triglycerides, glucose, or C-reactive pro-
tein. For all other measures, determination of adverse or posi-
tive effects was based on changes from baseline that were
initially normal or abnormal but were the opposite at the end
of the study. None of these changes were found on any of the
remaining blood tests.
Adverse Effects
No significant adverse effects were reported by subjects in
either of the study groups. No adverse changes in blood chem-
istries, fat-free mass, or bone density were found.
DISCUSSION
Using a double-blind, placebo-controlled protocol, this
study compared changes in DEXA-measured body composi-
tion and a panel of 42 blood chemistry measurements as
a function of taking a dietary supplement containing 3 g of
konjac glucomannan fiber combined with 300 mg of calcium
carbonate with a placebo group taking only the 300 mg of
calcium carbonate. The amount of calcium in both groups
was used by the sponsor as a “filler” and was assumed to
have little or no effect on bone density because it was far
below the recommended amounts for daily consumption of
this element [17,18]. The study was conducted over the holi-
day period from October to early January to see whether it
could help combat the weight gain and detrimental body com-
position (lean, fat, and bone) changes that normally occur dur-
ing this season.
Table 5. Average Changes (delta) after 2 Months on Protocol
between Compliant and Noncompliant Placebo Groups
Placebo
Minutes
Parameter Compliant (22) Noncompliant (20) A-P
a
p
Weight (lb) 1.87 §0.98 0.50 §1.03 1.37 0.34
Body fat (%) 0.49 §0.38 0.57 §0.40 ¡0.08 0.87
Fat mass (lb) 1.21 §0.84 0.99 §0.88 0.22 0.86
FFM (lb) 0.66 §0.73 ¡0.49 §0.76 1.15 0.28
BCI (lb) ¡0.55 §1.22 ¡1.48 §1.28 0.93 0.60
BMD (g/cm
2
)¡0.24 §0.39 ¡0.04 §0.41 ¡0.21 0.72
#Capsules
Parameter Compliant (32) Noncompliant (10) A-P p
Weight (lb) 1.21 §0.82 1.22 §1.47 ¡0.01 1.00
Body fat (%) 0.69 §0.31 0.00 §0.55 0.69 0.28
Fat mass (lb) 1.38 §0.69 0.23 §1.23 1.15 0.42
FFM (lb) ¡0.16 §0.60 0.99 §1.08 ¡1.15 0.36
BCI (lb) ¡1.54 §1.00 0.76 §1.79 ¡2.30 0.27
BMD (g/cm
2
)¡0.22 §0.33 0.10 §0.58 ¡0.32 0.64
Both
Parameter Compliant (18) Noncompliant (24) A-P p
Weight (lb) 2.18 §1.08 0.49 §0.93 1.69 0.96
Body fat (%) 0.54 §0.42 0.52 §0.36 0.02 0.24
Fat mass (lb) 1.39 §0.92 0.89 §0.80 0.51 0.68
FFM (lb) 0.79 §0.80 ¡0.40 §0.69 1.19 0.27
BCI (lb) ¡0.60 §1.35 ¡1.28 §1.17 0.68 0.70
BMD (g/cm
2
)¡0.03 §0.43 ¡0.23 §0.38 0.20 0.74
FFM Dfat-free mass, BCI Dbody composition improvement, BMD Dbone
mineral density.
a
Change from baseline and study completion, defined as the value at the last visit
minus baseline (for weight and fat changes, negative values indicate benefit,
whereas the opposite pertains to FFM, BMD, and BCI).
Table 6. Average Changes (delta) after 2 Months on Protocol
between Active Treatment and Placebo Groups in Compliant
Subjects
Compliant
Minutes
Parameter Active (19) Placebo (22) A-P
a
p
Weight (lb) ¡2.87 §0.85 1.87 §0.79 ¡4.74 <0.001
Body fat (%) ¡0.83 §0.34 0.49 §0.31 ¡1.32 0.007
Fat mass (lb) ¡2.49 §0.76 1.21 §0.70 ¡3.70 <0.001
FFM (lb) ¡0.38 §0.73 0.66 §0.68 ¡1.04 0.30
BCI (lb) 2.11 §1.22 ¡0.55 §1.13 2.66 0.12
BMD (g/cm
2
)¡0.36 §0.46 ¡0.24 §0.43 ¡0.12 0.85
#Capsules
Parameter Active (25) Placebo (32) A-P p
Weight (lb) ¡0.48 §0.96 1.21 §0.85 ¡1.69 0.19
Body fat (%) ¡0.23 §0.35 0.69 §0.31 ¡0.92 0.05
Fat mass (lb) ¡0.76 §0.80 1.38 §0.70 ¡2.14 0.05
FFM (lb) 0.28 §0.68 ¡0.16 §0.60 0.44 0.63
BCI (lb) 1.04 §1.12 ¡1.54 §0.99 2.58 0.09
BMD (g/cm
2
)¡0.56 §0.35 ¡0.22 §0.31 ¡0.34 0.47
Both
Parameter Active (16) Placebo (18) A-P p
Weight (lb) ¡2.75 §0.95 2.18 §0.89 ¡4.93 <0.001
Body fat (%) ¡0.81 §0.37 0.54 §0.35 ¡1.36 <0.01
Fat mass (lb) ¡2.47 §0.87 1.39 §0.82 ¡5.30 <0.003
FFM (lb) ¡0.28 §0.79 0.79 §0.75 ¡1.07 0.33
BCI (lb) 2.19 §1.37 ¡0.60 §1.29 2.79 0.15
BMD (g/cm
2
)¡0.64 §0.49 ¡0.03 §0.47 0.60 0.38
FFM Dfat-free mass, BCI Dbody composition improvement, BMD Dbone
mineral density.
a
Change from baseline and study completion, defined as the value at the last visit
minus baseline (for weight and fat changes, negative values indicate benefit,
whereas the opposite pertains to FFM, BMD, and BCI).
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION 5
Glucomannan and Body Composition
Glucomannan is extracted from the tubers of the konjac
plant and has been used in the Orient, particularly Japan, for
over 1,000 years [19]. It is a water-soluble fiber with the high-
est molecular weight and strongest viscosity among any die-
tary fiber known to science, and it can absorb up to 100 times
its weight in water. Some previous studies have reported that
glucomannan can decrease appetite, lower serum cholesterol,
and improve glucose or blood sugar control in people with
diabetes [20–25]. These studies also suggest that it can reduce
the glycemic index of carbohydrates, resulting in improved
glucose control, lowered insulin levels, and reductions in
serum total and LDL cholesterol. It has been proposed that
lowered insulin levels result in less storage of dietary fat and
increased utilization of stored fat [26]. The ability of gluco-
mannan to quickly and profoundly absorb water suggests that
it may lead to a swelling in the stomach, resulting in conse-
quent feelings of fullness and decreased appetite.
Effort was expended to achieve “real world” conditions by
minimizing the exclusion criteria and enrolling participants
who closely resembled the consumers who were most likely to
use the product [27–29].
From the standpoint of exposing study participants to
risks, it was impossible to know all of the medical condi-
tions that might be affected by participation in the study and
consumption of the dietary supplements, particularly without
knowing the subject’s personal medical history and medical
conditions [30]. Listing the medical conditions that would
exclude participation could imply that the investigators
know what conditions will be affected by participation and
which ones would not, which is rarely, if ever, the case for
untested products. Study participants with unspecified condi-
tions might assume that because their medical condition was
not listed, there were no risks associated with their condi-
tion. Therefore, to reduce this risk, subjects were asked to
provide their personal physicians with a copy of the
informed consent and a list of product ingredients to see
whether they had any medical conditions that would exclude
them from the study. When completing and signing the
informed consent form, participants were asked to certify
that they had reviewed their participation with their physi-
cians or health care providers.
After enrollment, care was taken to emphasize among sub-
jects the importance of complying with the protocol; that is,
taking the correct daily dose of the supplement at the appropri-
ate time. We believe that these instructions were given in a
manner comparable to other clinical studies concerning weight
loss and certainly in a manner that was more stringent than
those characteristically given in a busy office practice setting.
However, as shown in Table 3, despite these efforts, less than
half of the subjects fully complied with the dosing instructions.
Accepting the overall data without considering compliance
fully as in most weight loss studies, the conclusion from our
study would be that glucomannan had no effect [16].
However, the expanded data in the present study allowed a
different conclusion. When taken as directed (compliance),
the glucomannan supplementation facilitated a loss of excess
body fat without essentially any concomitant loss of FFM or
BMD. These positive changes were found in comparisons
between the active treatment and placebo groups and when
using within-group comparisons between compliant and non-
compliant subjects. These changes did not occur between the
compliant and noncompliant placebo groups. Taking the sup-
plement correctly also led to decreased circulating total and
LD cholesterol levels. It is also worth noting that these
changes occurred during a holiday season (October, Novem-
ber, and December) when people typically gain weight and
avoid dieting.
CONCLUSIONS
These data support the safety and efficacy of using a glu-
comannan dietary supplement to facilitate improvements in
body composition (lean, fat, and bone) and serum lipid levels.
These data also illustrate the importance of 2 potentially con-
founding procedures when conducting weight loss research.
One is the importance of using changes in body composition,
instead of scale weight or body mass index (BMI), as out-
come measures. The data support our previous contentions
that using scale weight or BMI changes assesses only the
amount, but not the kind, of weight that is lost or gained in
weight control interventions [15,30]. When using scale weight
and BMI, failing to distinguish changes in FFM (lean and
bone) from changes in body fat could significantly distort the
conclusions that would be drawn regarding the success or fail-
ure of weight loss interventions. One cannot help but reason
that many weight loss studies have been erroneously inter-
preted by failing to make this distinction. Another conclusion
to be drawn from the present study is the importance of incor-
porating measures of compliance or adherence. The positive
changes in body composition and lipid levels reported were
not evident until corrections for compliance were applied to
the study data. Had they not be applied, the efficacy of using
a glucomannan supplement would have been masked
completely, a concern we expressed in a previous manuscript
[30]. The absence of safety concerns found in this and other
studies as well as the effects of compliance on reported effi-
cacy suggests the need for additional and longer-term studies.
FUNDING
Although Natural Alternatives International, Inc. (NAI),
San Marcos, California, provided funding for this study, at no
time did it have access to the data or participate in the statisti-
cal analyses or review of this article.
6 VOL. 0, NO. 0
Glucomannan and Body Composition
REFERENCES
1. Iacobellis G, Ribaudo MC, Leto G, Zappaterreno A, Vecci E, Di
Mario U, Leonetti F: Influence of excess fat on cardiac morphol-
ogy and function: study in uncomplicated obesity. Obes Res
10:767–763, 2002.
2. Kenchaiah S, Evans JC, Levy D, Wilson PW, Benjamin EJ, Lar-
son MG, Kannel WB, Vasan RS: Obesity and the risk of heart fail-
ure. N Eng J Med 347:305–313, 2002.
3. Danaei G, Ding EL, Mozaffarian D, Taylor B, Rehm J, Murray
CJ, Ezzati M: The preventable causes of death in the United
States: comparative risk assessment of dietary, lifestyle, and met-
abolic risk factors. PLoS Med 6:1000058, 2009.
4. Wagner K-H, Brath H: Global view on the development of non-
communicable diseases. In Bagchi D, Preuss HG (eds): “Obesity.
Epidemiology, Pathophysiology, and Prevention.” Boca Raton,
FL: CRC Press, pp 45–52, 2013.
5. Ogden CL, Carroll MD, Kit BK, Flegal KM: Prevalence of child-
hood and adult obesity in the United States, 2011–2012. JAMA
311:806–814, 2014.
6. Koh K, Blakey CR, Roper AY: Healthy People 2020: a report card
on the health of the nation. JAMA 311:2475–2476, 2014.
7. Chevallier JM: From bariatric to metabolic surgery: 15 years
experience in a French university hospital. Bull Acad Natl Med
194:25–36, 2010.
8. Kasalicky M: Contemporary overview of the bariatric–metabolic
surgery. Rozhi Chir 91:5–11, 2012.
9. Cerulli J, Lomaestro BM, Malone M: Update on the pharmaco-
therapy of obesity. Ann Pharmacol 32:88–102, 1998.
10. Carek PJ, Dickerson LM: Current concepts in the pharmacological
management of obesity. Drugs 57:883–904, 1999.
11. Food and Drug Administration: Early communications about
ongoing safety review Orlistat (marketed as Alli and Xeni-
cal). 2009. Accessed at http://www.fda.gov/Drugs/DrugSaf
ety/PostmarketDrugSafetyInformationforPatientsandProviers/
DrugSafetyInformationforHeathcareProfessionals/
ucm179166.htm
12. Gupta AK, Greenway FL: Safety of obesity drugs. In Bagchi D,
Preuss HG (eds): “Obesity. Epidemiology, Pathophysiology, and
Prevention.” Boca Raton, FL: CRC Press, pp 327–348, 2013.
13. Khandalavala B, Chatterjee A: Historical perspectives, efficacy of
current drugs, and future directions in management of obesity. In
Bagchi D, Preuss HG (eds): “Obesity. Epidemiology, Pathophysi-
ology, and Prevention.” Boca Raton, FL: CRC Press, pp 349–364,
2013.
14. Preuss HG, Gottlieb W: “The Natural Fat Loss Pharmacy.” New
York: Broadway Books, pp 1–260, 2007.
15. Kaats GR, Michelak JE, Preuss HG: An evaluation of the efficacy
and safety of a chitosan fiber product. J Am Coll Nutr 25:389–
394, 2006.
16. Onakpoya I, Posadzki P, Ernst E: The efficacy of glucomannan
supplementation in overweight and obesity: a systematic review
and meta-analysis of randomized clinical trials. J Am Coll Nutr
33:70–78, 2014.
17. Standing Committee on the Scientific Evaluation of Dietary Refer-
ence Intakes, Food and Nutrition Board, Institute of Medicine.
“Dietary Reference Intakes for Calcium, Phosphorus, Magnesium,
Vitamin D and Fluoride.” Washington, DC: National Academy
Press, 1997.
18. Weaver CM, Heaney RP: Calcium. In Shils ME, Shike M, Ross
AC, Caballero B, Cousins RJ (eds): “Modern Nutrition in Health
and Disease.” 10th ed. Baltimore, MD: Lippincott Williams &
Wilkins, pp 194–210, 2006.
19. Swanson B, Keithley JK: Glucomannan in weight loss: a
review of the evidence. In Bagchi D, Preuss HG (eds):
“Obesity: Epidemiology, Pathophysiology.” Boca Raton, FL:
CRP Press, pp 433–442, 2007.
20. Keithley J, Swanson B: Glucomannan and obesity: a critical
review. Altern Ther Health Med 11:30–34, 2005.
21. Walsh DE, Yaghoubian V, Behforooz A: Effect of gluco-
mannan on obese patients: a clinical study. Int J Obes 8:289–
293, 1984.
22. Arvill A, Bodin L: Effect of short term ingestion of konjac gluco-
mannan on serum cholesterol in healthy men. Am J Clin Nutr
61:585–589, 1995.
23. Martino F, Martino E, Morrone F, Carnevali E, Forcone R,
Niglio T: Effect of dietary supplementation with gluco-
mannan on plasma total cholesterol and low density lipopro-
tein cholesterol in hypercholesterolemic children. Nutr Metab
Cardiovasc Dis 15:174–180, 2005.
24. Gallaher DD, Gallaher CM, Mahrt GJ, Carr TP, Hollingshead CH,
Hesslink R Jr, Wise J: A glucomannon and chitosan fiber supple-
ment decreases plasma cholesterol and increases cholesterol
excretion in overweight normocholesterolemic humans. J Am
Coll Nutr 21:428–433, 2002.
25. Chen HL, Sheu WH, Tai TS, Liaw YP, Chen YC: Konjac sup-
plement alleviated hypercholesterolemia and hyperglycemia in
type 2 diabetic subjects—a randomized, double blind trial. J
Am Coll Nutr 22:36–42, 2003.
26. Preuss HG: Bean amylase inhibitor and other carbohydrate
absorption blockers: effects on diabesity and general health. J Am
Coll Nutr 28:266–276, 2009.
27. Tunis SR, Stryer DB, Clancy CM: Practical clinical trials: increas-
ing the value of clinical research for decision making in clinical
and health policy. JAMA 290:1624–1632, 2003.
28. Bailar JC: The powerful placebo and the Wizard of Oz. N Engl J
Med 344:1630–1632, 2001.
29. Tudor-Locke C, Bell RC, Myers AM, Harris SB, Ecclestone
NA, Lauzon N, Rodger NW: Controlled outcome evaluation
of the First Step Program: a daily physical activity interven-
tion for individuals with type 2 diabetes. Int J Obes 28:
113–119, 2004.
30. Kaats GR, Preuss HG: Challenges to the conduct and interpreta-
tion of weight loss research. In Bagchi D, Preuss HG (eds):
“Obesity. Epidemiology, Pathophysiology, and Prevention.” Boca
Raton, FL: CRC Press, pp 833–852, 2013.
Received August 15, 2014; accepted January 14, 2015.
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION 7
Glucomannan and Body Composition
