Beneficial effects of catechin-rich green tea and inulin on the body
composition of overweight adults
Hsin-Yi Yang1,2, Suh-Ching Yang3, Jane C.-J. Chao3and Jiun-Rong Chen2,3*
1Department of Nutrition, I-Shou University, Yanchao District, Kaohsiung City, Taiwan, ROC
2Nutrition Research Center, Taipei Medical University Hospital, Taipei, Taiwan, ROC
3Department of Nutrition and Health Sciences, Taipei Medical University, 250 Wu-Hsin Street, Taipei 110, Taiwan, ROC
(Received 8 December 2010 – Revised 16 December 2010 – Accepted 9 February 2011 – First published online 28 October 2011)
Green tea catechin has been proposed to have an anti-obesity effect. The aim of the present study was to investigate whether the effect of
catechin-rich green tea in combination with inulin affects body weight and fat mass in obese and overweight adults. A total of thirty sub-
jects were divided into a control group and an experimental group who received 650ml tea or catechin-rich green tea plus inulin. A
reduction of body weight (21·29 (SEM 0·35)kg) and fat mass (0·82 (SEM 0·27)kg) in the experimental group was found after 6 weeks,
and no adverse effects were observed. After refraining from consumption for 2 weeks, sustained effects on body weight and fat mass
were observed. We conclude that continuous intake of catechin-rich green tea in combination with inulin for at least 3 weeks may be ben-
eficial for weight management.
Key words: Green tea: Catechins: Inulin: Obesity: Body fat
Morbidity from overweight and obesity is increasing, leading
to numerous health problems. Prolonged excess energy
intake and decreased energy expenditure lead to body fat
accumulation. Obesity, especially visceral obesity, carries a
strong risk of some related CVD and metabolic diseases,
such as the metabolic syndrome, hyperlipidaemia, hyperten-
sion and diabetes mellitus(1). Lifestyle modification, especially
changing dietary habits, plays an important role in the
management of obesity. Both increasing energy expenditure
and decreasing energy intake may stimulate weight loss and
improvement of body composition.
the world. Green tea-derived polyphenols such as epigallocate-
chin gallate (EGCG), the most abundant catechin in tea, have
been reported to produce physiological effects, including anti-
oxidative, anticancer, anti-obesity and hypolipidaemic effects.
Epidemiological studies in Taiwanshow aninverse relationship
Human and animal studies have explored the mechanism by
which green tea catechins may be beneficial for the prevention
or treatment of obesity. EGCG may decrease energy intake by
reducing food intake, interrupting lipid emulsification and
absorption, and increasing energy expenditure via thermogen-
esis, fat oxidation and faecal lipid excretion, and this so far
only has been shown in animal studies. However, information
from human studies is still limited(4).
Inulin-type fructans are a linear polydisperse carbohydrate
material consisting mainly of b-(2 ˆ 1) fructosyl-fructose link-
ages. They resist hydrolysis by human digestive enzymes;
thus, they are recognised as a kind of non-digestive oligosac-
charide(5). Inulins are now widely used as an ingredient of
functional foods for its properties as dietary fibre and prebio-
tics. A series of studies has demonstrated that inulin affects
lipid homeostasis and metabolism, and body weight, though
the mechanisms remain unclear(6,7). Therefore, the present
study was designed to investigate whether habitual consump-
tion of green tea beverages containing high doses of catechins
in combination with inulin can produce weight loss and fat
redistribution in overweight subjects.
Materials and methods
Preparation of green tea
For the experimental group, 28g of green tea leaves (Camellia
sinensis) were extracted with 2 litres of hot water (708C) for
8min and then filtered to get the tea extract; for the control
group, 8·5g of tea leaves were extracted in the same
manner as above. In addition, 18g inulin powder/l (.85%
*Corresponding author: J.-R. Chen, fax þ886 2 2737 3112, email email@example.com
Abbreviation: EGCG, epigallocatechin gallate.
British Journal of Nutrition (2012), 107, 749–754
q The Authors 2011
British Journal of Nutrition
fructo-oligosaccharides; average chain length: seven mono-
mers; Sensus, Roosendaal, Netherlands) were added to the
experimental green tea as a source of dietary fibre and to
make the two beverages indistinguishable in taste. The final
catechin concentrations were 81 and 267mg/bottle in the con-
trol and experimental tea, respectively. The two beverages
were packed identically in 325ml bottles.
A total of thirty volunteers, aged 20–50 years old, with BMI
$24kg/m2were recruited for the present trial (Table 1).
Subjects were recruited by announcement at Taipei Medical
University and Taipei Medical University Hospital (Taipei,
Taiwan). The exclusion criteria were as follows: use of medi-
cations and supplements; consumption of other tea products
1 week before and during the experimental period; postmeno-
pausal women; systemic, liver, renal and digestive diseases.
Before the experiment, we explained the content, purpose
and possible risks of the study to all subjects and written
informed consent was obtained from all subjects.
The study was conducted according to the guidelines laid
down in the Declaration of Helsinki and all procedures invol-
ving human subjects/patients were approved by the Human
Investigation Review Board of Taipei Medical University and
performed under the supervision of a family medicine
doctor and dietitians from the Taipei Medical University
Hospitals. Written informed consent was obtained from all
subjects. Subjects were assigned to either the control (n 15)
or the experimental group (n 15) through stratified randomis-
ation according to age, sex and BMI. During the 6-week
experimental period, subjects ingested the tea beverage
(650ml/d) and consumed three meals (7531–8368kJ) per d
offered by the Taipei Medical University Hospital. The con-
sumption of other food and beverages containing catechins,
polyphenols or caffeine was prohibited. Subjects were also
advised to maintain their physical activity levels. After the
6-week experimental period, all subjects continued with
another 2-week follow-up period without ingestion of any
tea beverages. Subjects were asked to record their daily diet-
ary intake for 3d at baseline, 6th and 8th weeks, and the
records were reviewed by a dietitian.
Height, body weight, waist circumference and hip circumfer-
ence were measured while the subjects were in standing pos-
ition at baseline, 3rd, 6th and 8th weeks. Waist circumference
was assessed using a tape measure around the mid-distance
between the last rib margin and the iliac crest. Hip circumfer-
ence was measured at the level of the largest circumference
around the hip. The body fat ratio was measured by the
bioimpedance analysis method (InBody 3.0 body composition
analyser; Biospace, Seoul, Korea).
Blood pressure measurements
After a 5min rest, blood pressure was measured on the right
arm with an automatic blood pressure monitor (FT-500R;
Jawon, Kyungsan, Korea). Systolic and diastolic blood press-
ure was calculated as the average of three measurements.
Blood sampling and clinical analysis
All biochemical analyses were carried out on a Hitachi 7170
Autoanalyser (Hitachi, Tokyo, Japan). We also measured cardio-
pulmonary functions of all subjects at the beginning and end
of the study. The electrocardiogram was recorded with the
Page Writer Trim III Cardiograph (Philips, Burlington, MA, USA)
and the lung function test was performed with a spirometer
(KoKo Legend Spirometer; nSpire Health, Longmont, CO, USA).
All evaluation data are presented as means with their standard
errors. The difference in percentage of males and females
between the control and experimental groups was assessed
Table 1. Characteristics of the subjects before and after the intervention
(Mean values with their standard errors, n 15)
Control groupExperimental group
Waist circumference (cm)
Hip circumference (cm)
Total fat mass (kg)
Lean body mass (kg)
* Mean values were significantly different from W0 in the same group (P,0·05).
H.-Y. Yang et al.750
British Journal of Nutrition
by the x2test. The age, body composition, anthropometric
and biochemical analysis of the two groups were evaluated
by Student’s t test, and differences between the values of
each time point and the initial measurement were analysed
by the paired t test. A P value ,0·05 was considered to be
Subjects and dietary intake
Basal characteristics of the subjects assigned to different groups
are shown in Table 1. No difference was found in age, weight,
BMI, fat mass, waist and hip circumference between the control
and experimental groups at baseline. All subjects consumed
three meals per d offered by the hospital and were also asked
to keep diet records at baseline, 6th and 8th weeks to evaluate
their dietary intake. There was no significant difference in
energy intake or protein, fat and carbohydrate composition of
the diet between the two groups during the experimental and
follow-up periods (P.0·05). All subjects consumed their study
beverage as instructed during the experimental period.
Body weight, body composition, waist and hip
Reduction in body weight, BMI and fat mass in the experimen-
tal group was significantly different from that of the control
Changes in body weight (kg)
Changes in BMI (kg/m2)
Changes in fat mass (kg)
Changes in lean
body mass (kg)
Changes in waist
Changes in hip
Fig. 1. Changes in (a) weight, (b) BMI, (c) fat mass, (d) lean body mass, (e) waist circumference and (f) hip circumference during the experimental and follow-up
periods. Values are means, with their standard errors represented by vertical bars (n 15). *Mean values were significantly different from those of the control group
(P,0·05; Student’s t test).
Green tea, inulin and body composition751
British Journal of Nutrition
group at 3rd and 6th weeks, and differences were maintained
at the 2-week follow-up period, as shown in Fig. 1. Hip and
waist circumference was reduced in the experimental group
compared with the control group after consuming the study
beverage for 6 weeks, although no significant difference was
found (waist, P¼0·07; hip, P¼0·06).
Blood pressure and blood biochemical analysis
Blood pressure and blood chemical measurement of all sub-
jects were within the normal range during the experimental
period. After consuming the study beverage for 6 weeks,
blood pressure and blood glucose concentrations were signifi-
cantly decreased in the experimental group. Diastolic blood
pressure and blood glucose in the control group were also
lower than the baseline values. Blood lipids in both groups
showed no change during the experimental and follow-up
periods (Table 2).
Safety and tolerability
No adverse event was found in either group. Hepatic and
renal function parameters were all within the normal range
(Table 2), and cardiopulmonary function and electrocardio-
grams were normal in all subjects during the experimental
and follow-up periods.
The present study shows that daily consumption of 650ml
catechin-rich green tea beverage plus inulin (534mg catechins
and 11·7g inulin) was acceptable and no adverse effect was
observed in our subjects. After 6 weeks, body weight, BMI,
fat mass and blood pressure were significantly decreased in
the experimental group. The result shows that catechin-rich
green tea plus inulin may have beneficial effects in people
who are overweight.
For overweight patients, reducing weight and fat mass is the
main target of diet modification. Many studies have reported
the effects of tea catechins on lipid metabolism and body fat
accumulation. Long-term consumption of tea catechins helps
to suppress high-fat diet-induced obesity via activation of
hepatic lipid metabolism(8). Daily intake of 300mg EGCG,
the main catechin in green tea, also has the potential to
increase fat oxidation in men(9). In addition, tea catechins
may reduce the deposition of visceral fat and hepatic fatty
acid synthesis(10), and EGCG supplementation prevents obes-
ity by reducing adipose tissue mass by inhibiting adipocyte
differentiation and reducing lipogenic enzyme expression(11).
The present study found that catechin-rich green tea
decreased fat mass and BMI. Although another study has
found that administration of tea catechins during a low-
energy diet had no additional effect on body weight and
body composition, and speculated that this may be due to
increased hunger with green tea treatment(12), we found no
difference in energy intake between the control and exper-
imental groups. Weight loss associated with green tea cate-
chins may involve its thermogenic properties and promoting
fat oxidation(13). Green tea may suppress body fat by reducing
digestibility of foods and increasing brown adipose tissue ther-
mogenesis via b-adrenoceptor activation(14). In one animal
study, long-term EGCG treatment (3·2g/kg) attenuated the
development of obesity and visceral fat(15). In a human
study, daily consumption of tea containing 690mg catechins
for 12 weeks reduced body fat in healthy Japanese men(16),
and catechin-rich beverages (576mg) ameliorated obesity
and decreased waist circumference and systolic blood press-
ure when compared with original green tea (75mg catechins)
without raising safety concerns in Japanese children(17). How-
ever, a double-blind study has found no effects of green tea
catechins on weight management(12). Another study has
demonstrated that catechin-rich tea extract (583mg/d) led to
a reduction in body fat in Japanese women and men with
visceral fat-type obesity after a 12-week experiment(18). In
addition, inulin-type fructan can also reduce body-weight
gain(7). In the present study, we added 18g inulin/l to a
catechin-rich green tea beverage and observed significant
weight loss and fat mass reduction after 3 weeks, when
compared with the control group, and the effects remained
2 weeks after refraining from consumption. These results
suggest that inulin and green tea catechins in our beverage
may be the effective components to induce weight loss
and fat mass. However, the mechanisms by which inulin
improves weight management is still very limited and needs
Green tea also contains caffeine, which may stimulate ther-
mogenesis, and 150mg caffeine/600mg catechins correspond
to approximately the content in three cups of green tea(19).
A meta-analysis has also shown that caffeine intake may
influence the effect of catechins on weight loss and weight
maintenance(20). Habitual high caffeine intake was associated
with a greater weight loss and relatively higher thermogenesis
and fat oxidation. However, this association has been found
during the weight-loss phase when subjects were put on a
low-energy diet(21). In a clinical study, subjects treated with
caffeine in amounts equivalent to those found in green tea
extract also showed no effect on energy expenditure and
respiratory quotient(13). Thus, the effect of catechin-rich
green tea beverage on body weight and fat mass cannot be
completely explained by its caffeine content.
A study has reported that green tea consumption protects
the cardiovascular system(18). In the present study, neither
the control group nor the experimental group showed a
change in blood lipids after the experimental period. A cross-
sectional study has demonstrated an inverse association
between green tea consumption and serum lipids(22). Another
study has also shown that habitual intake of green tea pro-
duced a significant reduction in plasma cholesterol and
TAG(23). Inulin intake may also regulate lipid homeostasis by
decreasing fatty acid synthase mRNA in hepatocytes(5). A poss-
ible reason for the absence of hypolipidaemic effect found by
the present study may be that the baseline blood lipid levels of
our subjects were within the normal range. Hypertension is
also a CVD risk in obese subjects, and habitual tea drinkers
have a lower risk of developing hypertension(24). Consistent
with this, we found a decrease in systolic and diastolic
H.-Y. Yang et al.752
British Journal of Nutrition
Table 2. Biochemical analysis and blood pressure of the subjects during the experimental and follow-up periods
(Mean values with their standard errors, n 15)
Control group Experimental group
W0 W3W6 W8W0 W3W6 W8
Heart rate (times/min)
Uric acid (mg/l)
W, week; SBP, systolic blood pressure; DBP, diastolic blood pressure; BUN, blood urea nitrogen; GOT, glutamate oxaloacetate transaminase; GPT, glutamate pyruvate transaminase, g-GT, g-glutamyltransferase; HDL-C,
HDL-cholesterol; LDL-C, LDL-cholesterol; T4, thyroxine; MCV, mean corpuscular value.
* Mean values were significantly different from W0 in the same group (P,0·05; paired t test).
Green tea, inulin and body composition
British Journal of Nutrition
blood pressure 3–6 weeks after consuming a catechin-rich
beverage plus inulin, and systolic blood pressure remained
lower than baseline even after the consumption had been
stopped for 2 weeks. These results suggest that catechin-rich
green tea beverage may also be beneficial for cardiovascular
In conclusion, frequent intake of catechin-rich green tea
in combination with inulin for more than 3 weeks may con-
tribute to weight loss, fat mass reduction and lower blood
pressure. The beneficial effects of catechin-rich green tea
beverage plus inulin suggest that sustained drinking may
contribute to managing weight in overweight populations,
and prevent further CVD and metabolic diseases.
The present study was funded by the Functional Food
Research Fund (Taipei Medical University, Taipei, Taiwan).
The contribution of each author was as follows: H.-Y. Y.,
S.-C. Y. and J. C.-J. C. performed the experiments and contrib-
uted to the writing of the manuscript; J.-R. C. designed the
study, and was the promoter, investigator and coordinator.
All authors read and approved the final contents of the
manuscript. The authors declare that there are no conflicts
of interest and adhere to the Committee on Publication
Ethics guidelines on research and publication practice.
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