There a few pleasures in life as enjoyable as a good cup of tea. The scent, the colour, the anticipation as you wait for it to cool enough for that first, tentative sip — it is a long sigh personified. A release.
As you can tell, I’m a fan of tea.
Green tea in particular is a subject of fascination. Made from a slightly different plant than black tea, and prepared differently, it is a beautiful blend of subtlety and flavour. A wonderful beginning to a long day, or a fitting end to a difficult one.
But, according to many people, that’s not all it is.
According to many, green tea is not just a delicious beverage — it can actually help you lose weight. It would be wonderful if true, health in one perfectly-brewed cup.
Unfortunately, the evidence is clear.
Green tea won’t make you lose weight.
Catechins, Polyphenols, And Other Long Words
The idea behind green tea as a weightloss tool is actually pretty interesting. The basic premise is that green tea has a number of biologically active molecules in it — chemicals that have effects on the way your body functions — and these chemicals are hypothesized to be able to make us lose weight.
The main compounds that people are interested in are called catechins, a type of polyphenol that is present in high quantities in green tea. These molecules are thought to do a number of things that might make us lose weight, for example reducing our absorption of fats.
There are also some large epidemiological studies that have found that people who drink more green tea are healthier than people who don’t drink much. This type of study can’t establish a causal relationship — we don’t know if these people are healthy because of the tea or something else — but taken with the evidence around catechins, it provides an interesting argument that green tea might cause weight loss.
What we’d need to see if green tea actually does do this is, ideally, a randomized controlled trial. You’d have one group of people taking a green tea supplement, compare them to another group taking a placebo control, and see if there was any difference between the two groups. In an ideal world, you’d have quite a few of these trials, so that you could look at them together in a systematic review, and see if green tea caused weight loss overall.
Lucky us, scientists have done exactly that.
So what did they find?
There have been a number of systematic reviews on the subject of green tea for weight loss over the last few years: one in 2009, another in 2012, two from 2014, and one more in 2015. There are fewer reviews on this question more recently, which is for a good reason that I’ll come to.
Let’s have a brief look at the conclusions of the reviews:
2009 — positive. Found a small but significant improvement in weight due to green tea
2012 — negative. No difference between green tea and placebo control
2014(1) — negative. No difference between green tea and placebo control (for weight loss)
2014(2) — negative. No difference between green tea and placebo control
2015 — negative. No difference between green tea and placebo control
So, if we look at the best current available evidence, there seems to be no difference between taking a placebo pill and taking one containing green tea extract*.
In other words, green tea won’t make you lose weight.
But is that the end of the story?
The evidence is clear: green tea doesn’t do anything for weight loss.
The reason that people aren’t really doing as much research on the question any more appears to be because they’ve taken a different tack. Green tea almost certainly doesn’t do anything for weight loss, but there is evidence that it might help in other places.
You see, there’s some research showing that green tea can reduce blood pressure. Not by an enormous amount — the average reduction appears to be somewhere around half of what you’d get from traditional medications — but even a small improvement is huge when you consider how safe green tea extracts are (they are mostly side-effect free).
But before you go and boil a fresh pot of liquid medicine, it’s important to note that these results are not consistent and may simply be due to the quality of the research on green tea. There’s also no evidence that some of the other claims made for green tea — that it helps with diabetes, for example — are well-supported.
However, what there is good evidence for is that replacing sugary drinks in your diet with unsweetened beverages like green tea is good for you. Not because green tea will do anything in and of itself, but because you’ll be consuming less Coke.
So what does this mean to you?
Well, firstly, definitely drink more green tea. It is delicious, cheap, and a great way to hydrate without adding extra calories. It might even help a bit to lower your blood pressure.
If you’re worried about your weight, go talk to a doctor and/or a dietitian. They study hard to give you the best advice about your health that they can.
But don’t drink green tea to lose weight.
The evidence shows that it won’t do anything to help at all.
*Note: these systematic reviews mostly looked at actual, powdered green tea extract as an entire food, NOT catechin compounds formulated from green tea.