The best summary, in laymen's terms, that I found on the
scientific studies of EGCG, the catechin found in green tea,
is provided in this article by Janet Raloff, titled, 'Trimming
with Tea' on the Science News Online website:
It first cites the original European study in which 10 men
received, over the course of 3 days, placebos, caffeine,
and EGCG (in the amount found in 2-3 cups of green tea).
The result was that the men burned more calories (80) on
the day they received EGCG, all else being equal.
This landmark study is described in much greater detail in
this article titled, 'Lose Weight with 5-HTP & EGCG', by
Will Block, the publisher and editorial director of Life
Enhancement magazine, on the LifeEnhancement website,
beginning in a section titled, 'EGCG and Caffeine Tested':
In the next section of her article, Raloff outlines the
much more in-depth study conducted by Nagao* and other
scientists at the Kao Corporation in Tokyo, involving
the study of 38 employees' weight over a period of months.
Half the employees were given a small dose (22mg) of the
green tea catechins (about the equivalent of one cup of
tea). The other half were given 690mg in the same amount
of product. The results were clear:
"...both groups of men lost weight?roughly 1.3 kilograms
for those drinking the low-catechins tea and 2.4 kg for
those on the brew heavily spiked with catechins.
More importantly, much of the weight loss in the latter
group came from fat. Compared with measurements of the
men before the trial began, total fat volume fell 10.3
percent in the average high-catechin-tea drinker but
just 2.6 percent in the others. Further analysis showed
that roughly equal proportions of subcutaneous fat
(stored in pads under the skin) and visceral fat (the
marbling within muscle and internal padding deep within
the trunk) disappeared in both groups. That's good
because although paring subcutaneous fat leads to a
slimmer physique, losing visceral fat is better for a
person's health. Visceral fat poses a greater risk of
heart disease and diabetes"
"The low-catechin tea drinkers shaved 1.6 centimeters
off their waistlines while the high-catechin group
trimmed off more than twice that much."
"...concentrations of triglycerides?which increase a
person's risk of heart disease?increased a little more
than 2 percent in the low-catechin group, they remained
unchanged in the high-catechin-tea drinkers. And although
cholesterol concentrations increased in both groups of
men, it climbed 6.3 percent in the low-catechin group but
only 3.4 percent in the others. Moreover, concentrations
of dangerous LDL cholesterol and oxidized-LDL cholesterol
dropped in both groups, but more than three times as much
? 11.5 percent and 36.3 percent, respectively?in the men
who drank the high-catechin brews."
More on the page:
The article lists multiple references, including that last
study, by Nagao* which is presented on the American Journal
of Clinical Nutrition website:
A search on Google Scholar also results in 977 results with
relevant studies and articles which may interest you:
"green tea" "weight loss"
On the other side of the coin, there is the page on 'Tea'
from the Micronutrient Information Center of the Linus
Pauling Institute at Oregon State University, which states:
"Weight reduction can be achieved by long-term decreases
in energy intake and/or increases in energy expenditure.
Several small short-term trials have reported modest 3-4%
increases in energy expenditure after the consumption of
oolong tea or green tea extract."
"At present, there is no evidence from controlled clinical
trials that tea or tea extracts promote weight loss or
improve weight maintenance in humans. Interestingly,
recent studies showed a lowering of tissue fat levels in
mice drinking green tea, black tea, or caffeine."
It is interesting to note, however, that the page of 70
references which lead them to this conclusion does not
contain a reference to the study conducted by Nagao*:
I would personally conclude that green tea should not
be considered a solitary solution to weight loss, but
it certainly helps in the reduction of fat tissue by
way of the increased fat oxidation and thermogenesis
which it promotes. This alone increases the ratio of
muscle tissue to fat, which promotes a higher metabolic
rate and further fat burning. Additionally, there are
numerous other benefits being discovered in relation
to green tea, including benefits for blood sugar,
cholesterol, bad breath, dental cavities, antioxidant
effects, and potentially anticarcinogenic qualities.
If you have any questions, please post a Request for
Clarification before rating this answer.
Additional information may be found from further exploration
of the links provided above, as well as those resulting from
the Google searches outlined below.
Searches done, via Google:
egcg "weight loss" scient
scientists "green tea" "weight loss"
...via Google Scholar:
"green tea" "weight loss"