Does Green Tea Really Work as A Weight Loss Supplement?

by Dr. Ahmed Zayed
Published on January 9, 2019 and last updated for accuracy on April 4, 2019

The road to a successful weight loss is long but rewarding. Every pound you lose can only serve as motivation to keep going and lose even more. A lot of natural products and ingredients can support weight loss endeavor, and green tea is one of them. In fact, green tea is quite a popular ingredient in weight loss products and chances are you’ve already used or come across some item which had this extract on the label.

You’re probably curious about the actual efficacy of green tea, just like I was. So, here’s what you need to know about green tea extract for weight loss.

Green tea overview

Green tea is considered the healthiest beverage on the planet, next to water of course. It’s a type of tea made from leaves of Camellia sinensis, an evergreen shrub or small tree native to East Asia, the Indian subcontinent, and southeast Asia. Different varieties of the shrub or tree have been identified, and each of them is used for a different tea.

Besides green tea, the Camellia sinensis varieties also give us black tea, white tea, yellow tea, and oolong. Green tea is made from unoxidized leaves and belongs to the group of less processed types of tea. As a result, it has a high concentration of antioxidants which are responsible for most health benefits of this tea. The primary active compounds of green tea are catechins such as epigallocatechin gallate (EGCG).

For centuries traditional Chinese medicine and medical practices of other cultures relied on green tea for treatment of many health conditions. Green tea is popular today too, thanks to its versatility. Is weight loss really one of its benefits? Read on to find out.

Can green tea really aid weight loss?

Green tea has become a popular weight loss aid. Just take a look at dietary supplements and other products marketed for weight loss, and you’ll see green tea is on the ingredient list. Popularity is one thing, but true potential is something else. Is green tea just a trend or it really works? It’s perfectly natural to ask this question, and you don’t want to take something for weight loss just because it’s a popular ingredient.

Well, it turns out green tea really works.

The September 2009 issue of the International Journal of Obesity published a review which found that green tea catechins are effective for weight loss and weight maintenance. The main objective of the review was to elucidate whether green tea indeed has a function in weight regulation. Scientists from the Netherlands identified 49 studies published in English on this topic, but 11 works matched requirements for the final selection.

Results of the review showed that catechins significantly decreased body weight and successfully maintained body weight after a period of weight loss. Interestingly, the study found that green tea catechins exhibited a seemingly smaller effect on Caucasians compared to Asians, but the difference wasn’t significant (1).

The Canadian Pharmacists Journal published an interesting paper which also investigated the efficacy of green tea for weight loss. The paper reviewed studies on this subject conducted in Japan and other countries. Findings revealed that participants in green tea group lost on average 0.2 to 3.5kg more than their counterparts in the control group (2).

Although evidence on this subject is promising, it’s important to carry out further research. Most studies use extracts that contain higher levels of active ingredients than tea bags.

How does green tea work?

We’ve already established that green tea promotes weight loss and weight maintenance, the question is – how? This wonderful tea uses multiple mechanisms to help you slim down and achieve your body goal in an entirely natural way. Below, you can see how green tea works to help you lose weight.

Faster metabolic rate

To lose weight successfully your body needs to burn more calorie than you consume through diet. That’s where your metabolism steps in! Faster metabolic rate is an important aspect of a successful weight loss, but you need to achieve it in a healthy manner. Green tea helps with that.

In most studies on this topic green tea increases metabolic rate by 3% to 4%, but in some research papers, the effect is as high as 8% (3, 4, 5).

As you can already presume the primary “culprits” for these effects are catechins.

While most papers focused on short-term effects, multiple studies confirmed long-term benefits as well. For instance, one study found that among 60 participants those who took green tea extract lost additional 7.3 pounds (3.3kg) and burned 183 more calories a day after three months compared to their counterparts who didn’t take green tea (6).

Green tea mobilizes fat from fat cells, aids fat burning

Fat, especially in the abdominal area, is stubborn and difficult to get rid of. Overweight and obese bodies have accumulated fat mass that puts a person’s health in danger. Fat loss is an important aspect of slimming down, but it can be difficult to find an ideal aid to sort this problem. It looks like green tea can be just the thing you need.

You see, green tea contains substances or compounds that promote fat loss. Caffeine is one of those substances. Even though a cup of green tea contains 24mg to 40mg of caffeine compared to 100mg to 200mg in a cup of coffee, the amount is still sufficient for moderate fat-burning effect. Caffeine is a stimulant that promotes fat burning and improves athletic performance (7).

In order to burn fat, the body needs to break it down in fat cells first and push it into the bloodstream — active compounds in green tea aid this process by enhancing the effects of fat-burning hormones like noradrenaline or norepinephrine. For example, EGCG inhibits an enzyme that breaks down norepinephrine (8).

A study from the American Journal of Clinical Nutrition revealed that men who took green tea extract burned 17% more fat than subjects who didn’t take it. Scientists concluded green tea enhances the fat-burning impact of exercise (9). Basically, it helps you burn more calories during a workout than you would lose without green tea.

Evidence also confirms that green tea catechins increase fat burning both during workout and rest (10). This is particularly important if we bear in mind that rest is equally important as exercise.

Green tea could make you eat fewer calories

A major problem we face when trying to lose or control weight is excessive calorie intake. We eat way too much because we feel hungry. In fact, most weight loss products work by reducing the number of calories you consume. Green tea could exhibit a similar effect. Some studies found that EGCG supplements or green tea extracts could decrease the amount of fat absorbed from foods, thus helping you eat less (11).

These effects haven’t been confirmed in human studies, though.

Stress management

Stress is a natural response of our body to sudden changes and unfamiliar events. Although we’d like to avoid stress entirely, that’s not really possible. The best we can do is to reduce exposure to stress triggers and find a unique way to manage or cope with stress. Why are we talking about stress now? Well, the answer is because stress plays a role in your body weight. More precisely, when left unresolved stress can lead to weight gain.

Research from Cell Metabolism found a reason why stress promotes weight gain. The cause is a relationship between fat cells and the timing of stress hormones (12). Besides weight gain, unresolved stress depletes energy levels, decreases productivity, and promotes fatigue. When tired you can’t (and don’t want to) exercise which is why it’s difficult to slim down. In fact, stress management is important for weight loss. A study from the Journal of Human Nutrition and Dietetics confirmed that subjects from the intervention group experienced a greater weight reduction due to stress management program (13).

Stress management is important for overall health including your weight loss, and green tea can help you achieve it. One study found that intake of green tea suppresses excessive stress response (14). July 2017 issue of the journal Nutrients confirmed that green tea intake was associated with lower stress and improved sleep quality (15).

Improved quality of sleep is a significant health effect of green tea. We’ve become a chronically sleep-deprived society, but what most of us fail to acknowledge is that sleep deprivation is closely related to stress. Plus, lack of sleep can also promote weight gain.

Basically, besides fat-burning effects and faster metabolism, green tea relaxes your mind and helps you sleep better which can also help you lose weight. When you feel calm, you’re more inclined to be mindful and motivated to take care of your body. This can only inspire you to change diet and exercise regularly.

Potential side effects

Green tea is generally safe for consumption, but it’s recommended to avoid drinking high amounts of it. Some adverse reactions associated with the intake of green tea include:

  • Headache
  • Stomach problems
  • Difficulty falling asleep
  • Anemia and iron deficiency
  • Vomiting
  • Dizziness
  • Nervousness
  • Diarrhea
  • Heartburn
  • Tremor
  • Confusion
  • Convulsions
  • Irritability

Bear in mind that the risk of side effects is low. Some adverse reactions could occur if you drink too much. While safe and healthy, green tea may not be suitable for everyone, at least not without doctor’s permission. It could interact with some drugs such as:

  • Taking amphetamines and ephedrine – green tea has a strong interaction with these drugs so consult your doctor before you decide to drink it
  • Antibiotics, adenosine, birth control pills – green tea has a moderate interaction with these drugs (16)

You should also be cautious if you already have some stomach problems, iron deficiency, anemia, anxiety disorders, glaucoma, liver disease, and if you’re pregnant or breastfeeding. Persons with these problems can still drink green tea but in lower amounts. It’s useful to ask your doctor whether it’s safe.


Green tea, the healthiest beverage in the world, has a wide range of health benefits that improve our quality of life. The tea has become a popular weight loss ingredient, but it’s natural to wonder whether it really works or not.

Multiple studies have confirmed that green tea works indeed. This wonderful tea promotes weight loss and weight management through multiple mechanisms. Some mechanisms of action include fat loss, stress management, faster metabolic rate. It’s useful to include green tea into your lifestyle.

If buying a supplement containing this ingredient make sure you read labels first and get the high-quality product. Remember, successful weight loss also requires lifestyle management that involves well-balanced diet and regular workouts. Plus, green tea enhances fat-burning effects of exercise.



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