Green tea extract is a great overall wellness supplement because of all of the health benefits associated with it. It does help speed up your metabolism meaning it aids in fatloss, but simply taking green tea will probably not show a huge difference in regards to visible fatloss. It is more something that works in the background as an extra boost to a well planned diet and exercise routine geared towards losing fat.
I personally use Green Tea extract year round due to its health benefits and the fact that its pretty damn cheap.
Here is a good summary of the health benefits of Green Tea and some more info can be found in this Wikipedia Article:
Green tea contains anti-oxidants that:
1. Helps to prevent cancer.
The is some strong evidence that green tea included in you every day diet can reduce bladder, colon, esophageal, pancreas, rectum, and stomach cancer up to 60%. An antioxidant known as "epigallocatechin gallate" (EGCG for short) is at least 100 more times more effective than vitamin C and 25 times more effective than vitamin E at protecting cells from harmful influence.
The amazing thing about it that EGCG it not only inhibits the growth of new cancer cells it also kills some of the existing cancer sells without harming the healthy ones.
2. Lowers "bad" cholesterol (known as LDL) and improves the ratio of "good" cholesterol (known as HDL). It explains why tea-drinkers can eat almost twice the foods containing cholesterol as those who don't drink green tea, but still have an equal
3. Stops the unnatural formation of blood clots which if not taken care of will cause thrombosis. It takes on added importance if you consider that thrombosis is one of the main causes of strokes and heart attacks.
4. Reduces high blood pressure by repressing angiotensin II which causes constriction of the blood vessels causing high blood pressure.
5. Lowers blood sugar (polyphenols and polysaccharides are the two main antioxidants are especially effective in lowering blood sugar). That helps prevent and relieve type-two diabetes.
6. Protects liver against toxins like alcohol and chemicals in cigarette smoke.
7. Promotes oral health by suppress the process of plaque formation and destroys the bacteria that forms plaque. It also destroys bacteria that causes bad breath, so after eating something sweet I suggest you drink a cup of green tea.
8. Destroys free radicals that cause aging.
9. Boosts your immune system function (because of its high concentration of polyphenols and flaveboids).
10. Possess antibacterial and antiviral properties.
Recent studies show that green tea inhibits the spread of disease, speeds up recovery from cold and flu. It also kills seven strains of food poisoning bacteria including clostridium, botulus and staphylococcus (which makes it a good treatment for diarrhea).
11. Helps your body to maintain healthy fluid balance and relieve fatigue and stress often caused by dehydration.
12. Blocks main receptors that produce allergic
13. Stimulates metabolism, calorie burning process and is wildly being used as an important part of a healthy diet.