Green Tea For Weight Loss

Last updated October 7th 2014

Green tea is renowned for its potential health benefits, and is often sold both as tea and in supplement form on the traditional medicine market to treat a number of conditions, including obesity.

Green tea has received an extremely large amount of media attention regarding the potential of its components to help treat a range of conditions, and improve health in general. The substance is best known for its catechin (antioxidant) content, and it is this component that supposedly holds the key to fighting diseases and improving general health. Of course, no single drink is going to wholly prevent the contraction of disease, but it may help to lower your chances of contracting certain conditions. Green tea is believed to improve blood flow, lower cholesterol, lower blood pressure, prevent cardiovascular diseases, improve brain activity, for example memory, and possibly reduce the chances of getting Alzheimer’s disease.

What Is Green Tea?

Green tea has been used to treat a great range of conditions in Chinese herbal medicine for centuries, and is now available to buy all over the world in a wide variety of forms. It is still particularly popular in Asian countries, and more recently, this popularity has spread to the West. The most common types of green tea include the well-known green, black, and oolong teas. Each of these products is made using the leaves of the plant ‘Camellia sinsensis’. The leaves are taken from the plant and steamed in order to produce green tea, and fermented to form black tea and oolong. It is these leaves that purportedly contain a significant amount of antioxidants, and the method of processing involves very little oxidation, ensuring that they maintain this important component.

Green tea contains more flavonoids – phytochemicals that may work as anti-oxidants and anti-carcinogens – than fruit and vegetables. The raw extract of green tea can now be found in a range of beverages, foods, dietary supplements, and even cosmetic products. It has received a lot of media attention surrounding its potential health benefits. Claims have been made that people who consume the substance regularly have a reduced risk of developing heart disease, some forms of cancer, diabetes, cardiovascular diseases, and obesity.

What Is Green Tea Claimed To Help Weight Loss?

Green tea is believed to have a beneficial effect on weight loss, and can often be found as an ingredient in weight loss supplements, as well as in beverage form. The principal component of green tea that aids weight loss is a catechin (a type of antioxidant) called epigallocatechin gallate (EGCG). This substance is thought to enhance the activity of fat burning enzymes in the body, and help to boost the metabolism. This means that the substance may increase the activity of cells in the body, helping them to burn calories faster, and also increase the activity of the enzymes that are used in the process of breaking down fat molecules.

In turn, any fat consumed in the diet should be broken down faster, rather than being stored as fat in the body, thus helping an individual to lose weight gradually. Both the metabolism boosting and fat burning effects of green tea will only be apparent if consumed alongside a healthy diet and regular exercise. Green tea also contains some caffeine, though not as much as would be found in regular tea. Caffeine too is believed to have some effects on weight loss, for example, it has been shown in some studies to increase the rate of metabolism, and is also believed to work as an appetite suppressant.

Caffeine supposedly alters the concentrations of certain appetite-related neurotransmitters in the brain, such as serotonin, reducing hunger cravings and making you feel fuller for longer. This should mean that consumers don’t snack as much in between meals, and possibly eat less during meals. Caffeine is also a stimulant, meaning that it increases energy levels, possibly making people more willing to perform exercise. These impacts could be beneficial to a weight loss regime, however it must be mentioned that the amount of caffeine found in most green teas is unlikely to have a significant effect.

Is There Any Evidence To Support These Claims?

Green tea has been thoroughly tested for its potential benefits to weight loss.

One study was performed on 60 obese subjects and was undertaken to investigate the impacts of green tea on weight loss. Over 12 weeks, half of the participants were randomly allocated to the test group, who consumed green tea daily, and the other half to a placebo group, who consumed a placebo daily. The authors concluded that green tea consumption does have an impact on decreasing body weight, and it achieves this by increasing energy expenditure and fat oxidation in the body.

A similar study was performed on individuals with metabolic syndrome. The impact of green tea beverages, or extracts, on weight loss in humans was tested. 35 subjects were used, all of whom were obese, and suffered from metabolic syndrome. Subjects were randomly assigned to either a control or test group. The control group consumed four cups of water per day, whilst the test group consumed four cups of green tea and two capsules per day. The trial continued for eight weeks, and it was concluded that green tea extract had a significant impact, helping to decrease bodyweight.

A number of studies have however, produced less positive results, here is an example of this. This study was performed on 100 obese female subjects. They were randomly allocated to either control or test group, who consumed either green tea or a placebo three times a day for 12 weeks. The results suggested that the green tea extract had no impact on the percentage decrease in bodyweight when compared to the placebo group.

This study also produced negative results. The authors aimed to test the effect of green tea on resting energy expenditure and substrate oxidation in overweight female subjects. Here, green tea extract was consumed alongside a low energy diet. 46 overweight female volunteers took part, and the subjects were randomly allocated to one of two groups. One of these groups consumed green tea extract daily, and the other a placebo, for 83 days. No significant difference was found between the weights of those taking the green tea or the placebo.

Another study attempted to examine the impacts of green tea on weight maintenance by preventing the regain of weight. 104 overweight and obese subjects took part. Subjects were allocated to either a treatment (green tea) or a control (placebo) group, all of whom dieted for four weeks before the trial began, the trial then ran 13 weeks. The authors concluded that green tea consumption had no impact on weight loss. Another was performed on 76 overweight and obese subjects; it was concluded here that a mixture of green tea and caffeine could lead to greater weight maintenance.

Overall, the results of clinical trials on green tea are varied, with some producing positive results, and others showing no significant difference between the impact of green tea or a placebo. It seems that the ingredient may work well for some people, but not for others.

How Does Green Tea Compare To Other Ingredients?  

There is an immensely wide range of weight loss products on the market, each of which contains different ingredients that claim to work to help people lose weight in different ways. This huge variety can make choosing between the products and working out which are most likely to work for you a very daunting concept. Here green tea will be compared to Garcinia cambogia, raspberry ketones, and green coffee bean – all of which are commonly used ingredients in weight loss products. Which areas of weight loss are tackled will be considered, and whether or not there is any scientific evidence to back up these claims will be reviewed.

Green Tea Vs Garcinia Cambogia

Green tea and Garcinia cambogia are ingredients that claim to work in quite different ways. Green tea works as a fat burning and metabolism booster. Garcinia cambogia on the other hand purports to work principally as a fat binder, but is also believed to have appetite-suppressing properties. Both of the ingredients have been the subjects of a number of clinical trials. The effectiveness of Garcinia cambogia as a weight loss agent has been tested on rats, mice, and humans. The results of these however, have been rather contradictory and largely inconclusive. Some studies have suggested that the substance may be useful for weight loss in rats and mice, however the same has not been found in human subjects, and unfortunately results from studies on small mammals are not directly transferable to humans.

More scientific studies have been performed on green tea, and a large number of these were done using human subjects. The results of these have too been varied, with some showing beneficial effects of green tea on weight loss, and others suggesting that the substance makes no difference. Overall, green tea has been more studied than Garcinia cambogia. Both ingredients have shown some promise as weight loss aids, but it seems that they may only work for some people.

Green Tea Vs Raspberry Ketones

Most products containing raspberry ketones claim that they work as fat burners and metabolism boosters; this is essentially the same way as green tea supposedly works to aid weight loss. Several scientific studies have been undertaken on the effectiveness of raspberry ketones; however, the majority of these are very early-stage studies that have been performed on small mammal subjects. The results of the clinical trials have generally shown positive results, but these results are not directly transferable to humans, and so more studies certainly need to be undertaken on human subjects before it can be stated whether or not the ingredient is likely to be of any use to aiding weight loss in humans.

Due to the fact that a number of studies have been performed on the impact of green tea on weight loss in humans, this ingredient is undoubtedly better studied, and thus any side effects are also better known. Raspberry ketones have received a lot of media attention, and customer reviews indicate that the substance does seem to work for some people. However, the evidence for its efficacy to date is lacking. Again, it seems to be the case that each of the ingredients may be beneficial for some people, but not for others.

Green Tea Vs Green Coffee Bean

Green coffee beans are essentially the raw form of the beans that are roasted to make everyday coffee; they have long been renowned for their potential use as weight loss aids, and have received plenty of media attention as such. Green coffee beans supposedly work as fat burners, metabolism boosters, and appetite suppressants. These claims are often made on product websites, though the exact mechanisms that they supposedly work by in the body are not made clear. Overall, it seems that they purport to work using very similar mechanisms to green tea.

Green coffee bean extract has been the subject of a few clinical trials. One study showed positive results on human subjects, and this trial is often used as ‘proof’ for the efficacy of the ingredient. This study has however faced a significant amount of criticism since publication, particularly based on the small amount of subjects used. Other studies on the ingredient have provided varied results, some of which are positive, and some showing no difference between weight lost in subjects taking green coffee beans and those taking placebos. Overall, studies of both green tea and green coffee beans have shown varied results. More studies need to be performed on green coffee beans in order to determine its efficacy.


Are There Any Other Benefits To Green Tea?


The polyphenols in green tea supposedly hold antimutagenic, antidiabetic, antibacterial, anti-inflammatory, and hypocholesterolemic properties, according to a paper that can be read here. It has been suggested in the past to benefit genital warts, cancer, weight management, and cardiovascular disease, though the results of these studies are varied. The American FDA has in fact approved an ointment for genital warts that includes a mixture of green tea catechins.

A number of studies have suggested that the consumption of green tea may have an inverse relationship with the risk of getting cancer; results of studies are however quite varied and contradictory. A study suggested that consuming over 10 cups of green tea per day can decrease the risk of humans contracting cancer, when compared to people consuming less than three cups per day. Drinking more green tea also seemed to delay the onset of cancer.

A study of overall mortality over a long period of time (11 years) found that green tea consumption was associated with reduce mortality as a result of all causes, and as the result of cardiovascular disease. The authors did however not find a relationship between green tea and mortality due to cancer. The authors of the above study also mention that there is a significant amount of evidence from studies undertaken in vitro and on animals that green tea can prevent cardiovascular disease and carcinogenic processes, but that these roles would have the same impact in humans are not known.

A review of the health benefits of green tea states that green tea is likely to have impacts as an anticarcinogenic as well as antitumor, improvements in cardiovascular health, and atherosclerosis. It also mentions that the substance may have an impact on stress reduction, and may reduce cholesterol levels in the blood.


What Side Effects Are Associated With Green Tea?


Although green tea does not contain as much caffeine as normal tea, it does still have a caffeine content, and as such may incur some of the resulting side effects. Caffeine is a stimulant and so can cause anxiety, jitteriness, headaches, heartburn, dizziness, sleeplessness, increased heart rate, and increased blood pressure. Green tea also contains tannins – substances that can cause gastro-intestinal problems; gastro-intestinal side effects can include excess stomach acid (so be aware of consuming the product if you suffer from stomach ulcers or acid reflux), diarrhoea, stomach cramps, nausea, and vomiting.

More serious problems that have been reported include liver issues and weak bones. Green tea can increase the amount of calcium that is excreted in the urine, and can cause (or at least worsen) osteoporosis. It has also been mentioned that tannins can lead to iron deficiencies, so be aware of this if you suffer from anaemia. It is recommended that you consult a doctor before consuming the product if you suffer from cardiovascular problems, diabetes, irritable bowel syndrome, liver disease, bone problems, or glaucoma. Avoid consuming the ingredient if you are pregnant. Overall, the benefits of green tea outweigh the possible side effects, but be aware of interactions in the body if you suffer from any pre-existing conditions.


Where Can You Buy Green Tea?


A wide variety of green teas are available to buy in beverage form at relatively low prices from an extremely large range of sources, including most of the large supermarkets in the United Kingdom, such as Sainsbury’s, Tesco, Morrison’s, and Asda. It is also available to buy from a wide range of retailers online, including from more specialist tea companies. Green tea extract can also be purchased in supplement form. These are also available to buy from well-known high street stores in the United Kingdom, such as Boots, Holland and Barrett, and many pharmacies, such as Lloyds. It is also easy to find the supplements to buy from well-known online stores.


Early research into green tea suggests that it has a wide range of benefits for overall health, and may reduce the risk of an individual contracting a number of life-threatening conditions. Green tea is very easy to buy in beverage or supplement form and has few side effects. Its ability to perform as a fat burner and metabolism booster is less well understood, although some studies have produced positive results in this area, too. Results from research regarding the benefits of green tea on weight loss have been varied, but it seems they may work for some people’s weight loss regimes, even though they may not be as beneficial to others.