— Diet Wiki Selected excerpts from the best websites —
…Green tea is one of the healthiest beverages on the planet.
It is loaded with antioxidants and various plant compounds that may benefit your health.
Some people even claim that green tea can increase fat burning and help you lose weight….
….Green tea made from the dried leaves and leaf buds of the Camellia sinensis plant is often touted as a natural remedy with many benefits, from weight loss promotion to prevention of cardiovascular disease.
Many people prefer to seek these benefits by taking green tea supplements, which are capsules that are either filled with dry green tea leaves or made with green tea extract—a substance prepared by soaking the green tea leaves in an alcohol solution to isolate active components such as epigallocatechin-3-gallate (EGCG).….
The useful parts of green tea are the leaf bud, leaf, and stem. Green tea is not fermented and is produced by steaming fresh leaves at high temperatures. During this process, it is able to maintain important molecules called polyphenols, which seem to be responsible for many of the benefits of green tea.
Antioxidants and other substances in green tea might help protect the heart and blood vessels.
Green tea can help you lose weight in many ways.
It has been shown to increase your metabolism and help burn more fat .
Green tea suppresses appetite and leads to less energy consumption .
Green tea also interacts with other compounds that burn fat as well as adrenaline to increase the body’s metabolic rate .
EGCG suppresses an enzyme that breaks down norepinephrine, so this increases the amount of norepinephrine in the body. This hormone signals for more fat cells to be broken down, which can now be used as energy .
In addition to these properties, green tea can increase your endurance. The exhaust time for patients that drink green tea was extended. This means that you can exercise for a longer time and be able to lose more weight .
There is conflicting evidence about the effects of green tea in obese people. Some early research shows that taking green tea extract can slightly improve weight loss in obese people. Other early research shows that drinking green tea or green tea-containing beverages can reduce body weight and body mass index (BMI) in obese adults or children. Some multi-ingredient products containing green tea have also shown benefit for weight loss. In most cases, the benefit of green tea on weight loss seems to be linked with the amount of catechins or caffeine contained in the beverage or supplement. However, not all research shows benefit. The best evidence to date suggests that taking green tea that contains caffeine might slightly reduce body weight in overweight and obese patients compared to caffeine alone. But the amount of weight loss is small and probably not meaningful.
The authors of a meta-analysis of six randomized controlled trials with a total of 98 participants found that caffeine alone or in combination with catechins significantly increases energy expenditure in a dose-dependent fashion compared with placebo . This effect might be important for maintaining weight loss by helping counteract the decrease in metabolic rate that can occur during weight loss. Catechins combined with caffeine also significantly increase fat oxidation, but caffeine alone does not. Other human research indicates that EGCG alone does not increase resting metabolic rate, fat oxidation, or the thermic effect of feeding (the increase in metabolic rate associated with the digestion and absorption of food) [162,163].Taken together, these findings suggest that green tea catechins and caffeine might act synergistically [41,157,158].
Another systematic review and meta-analysis included 15 randomized controlled trials, 6 of which examined the effects of caffeine (39–83 mg/day) with and without green tea catechins (576–690 mg/day) on anthropometric measurements. The authors reported that green tea catechins combined with caffeine over a median of 12 weeks modestly yet significantly reduced body weight by a mean of 1.38 kg and waist circumference by a mean of 1.93 cm compared with caffeine alone . Only two studies in this meta-analysis examined the effects of green tea catechins alone. Their results suggest that green tea catechins alone do not affect body weight or other anthropometric measurements. A subsequent trial also found that decaffeinated green tea extract containing EGCG (1,315 mg/day total catechins) for 12 months had no overall effect on body weight, BMI, or waist circumference in 121 overweight or obese postmenopausal women .
TL;DR: weight-loss relevant compounds found in green tea(catechins) work only alongside with caffeine(also found in green tea), resulting in a slight weight loss.
According to the National Cancer Institute, the polyphenols in tea have been shown to decrease tumor growth in laboratory and animal studies and may protect against damage caused by ultraviolet UVB radiation.
In countries where green tea consumption is high, cancer rates tend to be lower, but it is impossible to know for sure whether it is the green tea that prevents cancer in these particular populations or other lifestyle factors.
The health benefits of green tea extract are mostly due to its high antioxidant content.
Polyphenol antioxidants called catechins comprise the majority of green tea extract’s antioxidant content. Among the catechins in green tea, epigallocatechin gallate (EGCG) is the most researched and thought to provide the most health benefits.
The Mayo Clinic summarized some of the findings about green tea in 2008. A combination of epidemiological and population studies seem to suggest that the benefits of green tea may include: (4)
- Reducing atherosclerosis and risk of heart disease
- Lowering blood pressure
- Reducing cholesterol levels
- Reducing inflammation in arthritis cases
- Improving bone density
- Improving memory
- Preventing cancer
One study that looked at the consumption of up to 1200 mg of green tea catechins in supplement form in healthy adults reported:
- Abdominal pain
- Excess intestinal gas
- Muscle pain
- There have been some case reports of liver problems in people taking concentrated green tea extracts; however, these problems do not seem to be connected with green tea infusions or beverages.
- Green tea and green tea extracts contain caffeine, which can cause insomnia, anxiety, irritability, upset stomach, nausea, diarrhea, or frequent urination in some people.
- Green tea extract contains small amounts of vitamin K, which can inhibit the effectiveness of anticoagulant drugs.
Do not exceed 400mg of EGCG per day, as more has been associated with liver issues.