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With our appetite for low or zero sugar products increasing, artificial sweeteners are big business.

Food or drinks containing artificial sweeteners are often marketed as a healthier option, and it’s understandable why. Because artificial sweeteners are significantly sweeter than sugar, they can be used in very small amounts and contribute little to no calories. There are lots of types, but the most well researched are aspartame and saccharin.

A possible link between artificial sweeteners and cancer has been reported in the media. But despite lots of research in this area, there’s no convincing evidence that sweeteners in our food and drink increase the risk of cancer.

While there’s nothing to worry about from a cancer perspective, questions still remain about whether or not artificial sweeteners can help us lose weight. And as being overweight or obese increases the risk of 13 types of cancer, knowing whether they help is important.

But getting a solid answer to this question is tricky. Diet is notoriously difficult to study and so far, researchers have reached different conclusions. Overall, it looks like artificial sweeteners like aspartame aren’t causing harm, but they’re not having the big weight loss benefits that some people expected either.

Can we have our cake and eat it too?

If sweeteners are replacing a high calorie alternative, it seems logical that by reducing calories they should help with weight loss.

But whether this is the case is tricky to prove. It’s difficult to study the long-term impact of a specific part of our diet for lots of reasons. For one, measuring exactly how much people consume is hard. And there are lots of other things that could explain any differences – like other elements of a person’s diet or how much they exercise – so we need large studies that take these things in to account.

Most studies have looked at artificially sweetened drinks rather than sweeteners in foods, and the results are mixed. For this reason, the European Food Safety Authority won’t allow products containing artificial sweeteners to carry a weight loss health claim.

A 2016 review found that people using artificial sweeteners had both a lower calorie intake and reduced body weight. But these results should be treated with a healthy dose of scepticism as the study was conducted and funded by the International Life Sciences Institute, whose members include companies such as Coca-Cola, Red Bull and Pepsi. Each of these companies has a vested interested in the artificial sweetener business.

The results also don’t fully tally up with a more recent, independent analysis of 56 studies. This analysis found very little evidence to suggest low energy artificial or natural sweeteners, like stevia, are helping lots of people to lose weight.

But when 3 studies were picked out that only included overweight or obese adults, artificial sweeteners did provide a small benefit to weight loss. While positive for this group of people, the researchers say that larger and longer-term studies are needed to confirm this.

If not weight loss, then what about weight gain?

Surprisingly, some research has found that sweeteners might make us gain weight. But the latest review didn’t agree with this.

This raises an important question: if products containing artificial sweeteners contain less calories, why doesn’t the evidence show they are helping us to lose weight?

One explanation is something called ‘reverse causality’ – whereby people who are already overweight or obese are more likely to be choosing food or drinks with sweeteners to help with weight loss. This makes it difficult to say whether the artificial sweeteners or weight gain came first, or how one may affect the other.

But some researchers think there might be more going on, including effects on our gut health, appetite and desire for sweet foods.

But these are unproven theories.

Are sweeteners actually making us hungrier?

Throughout the day, our gut sends messages to our brain in the form of hormones. These hormones tell our brain when we are hungry or full. There has been some suggestion that sweeteners could interfere with these messages, and therefore make us eat more rather than less.

‘’When we eat food containing sugar, the gut produces more of the hormone that tells our brain we are full, and less of the hormone that tells our brain we are hungry. Currently, the evidence suggests that sweeteners don’t prompt the release of either of these gut hormones in humans,’ says Dr Ana Pinto, a nutrition researcher from King’s College London (KCL).

Does a diet or low-calorie option at lunch equal more at dinner?

If sweeteners aren’t affecting our gut, is there a psychological effect?

Some research has proposed a reward effect, in which we feel we have some ‘calories to spare’ if we have replaced a high calorie product with a diet alternative.

Daphne Katsikioti, who also studies nutrition at KCL, explains: “‘Some researchers have suggested that when we eat or drink products containing artificial sweeteners, we later compensate for the ‘missing’ energy by eating more.”

But she adds that there’s good evidence to suggest that this doesn’t happen and that artificial sweeteners can be helpful to reduce calories.

Finally, some people have suggested that the intense sweetness that comes from sweeteners could lead to a particularly sweet tooth in the long term. The latest review found very little evidence of this, so more research is needed to pin down if this a possible side effect of artificial sweeteners.

To sweeten or not to sweeten?

Despite the theories, the European Food Safety Authority have ruled that artificial sweeteners in food and drink pose no threat to our health if consumed within daily allowances. For aspartame, this is equivalent to 15 cans of diet coke. That’s a stark contrast to what we know about the harms of having too much sugar.

But products containing sweeteners often don’t offer much nutritional benefit. And the lack of convincing evidence that they can help with weight loss shouldn’t be overlooked.

The take-home message is artificially sweetened drinks aren’t a silver bullet for weight loss. But if you drink a lot of sugary drinks and think a diet version might help you cut down on sugar, that’s a good step and is very unlikely to do you any harm.

Katie Patrick is a health information officer at Cancer Research UK 


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Katie Roberts April 2, 2019

Hi Maureen,

Thanks for your question. Cancer Research UK works closely with members of the Scottish Parliament to make sure that cancer is at the top of the health agenda We’ve most recently been doing this as part of our campaign to tackle obesity in Scotland
We also provide updates on all devolved nations via our online news channels, including covering when new treatments are made available on the NHS in Scotland

Best wishes,

Katie Roberts, Cancer Research UK

Maureen Gibb March 29, 2019

Never much about NHS Scotland. Why? Contributed by direct debit for over 20 years and would like to know if Scotland is on your radar.

Tracy Eaton March 24, 2019

Thankyou this has answered several questions I had as people saying to me since my cancer stop all sugar it gives you cancer but so does aspartame so stop and look at ingredients. Don’t have it . It becomes confusing and scaremongering. I feel now I can still with too much worry still have a single can of diet coke aday. Moderation the key

John black March 14, 2019

My dad needs help to lose weight

Steve February 18, 2019

This article doesnt really add value, just makes things more confusing. The only reassuring part is breaking the link between sweetners and cancer.

Jill February 18, 2019

For me anything artificial is dangerous. I try and steer well away.
Better to have as less as possible of anything artificial in your diet.

Ivy Pound February 18, 2019

I’m a retired Slimming World consultant and members who switched to sweeteners did lose weight

Cay Thorn February 18, 2019

Very confusing

Isobel Edgar February 18, 2019

What about people who are boarding on diabetic and have replaced sugar in tea coffee and on cereal with a sweetener? Is this healthier? Also is it safe for my 10 year old to have diet lemonade he prefers it to the sugared ones. He only has it at the weekends as a treat. But with a family history of diabetes I am very cautious about giving him too much sugar.
Mrs Edgar

Bilikisu Savage February 17, 2019

Thank you for the comprehensive educative information.

Ley Holloway February 17, 2019

I’ve never liked the idea of artificial anything, Aspartame particularly has a very unpleasant aftertaste so i won’t drink anything containing it, recently gave up on J20 since it’s artificial sweetener content has risen. If they help people cut down on their sugar intake then I suppose they’re a good thing. Not for me though.

Olivia February 17, 2019

I think anything artificial is daft over something that is natural!
If you must sweeten???! ; Understand sugar is a drug and not necessary like salt. Use honey (local if you can, less likely to develop allergy).

Matthew Inge February 17, 2019

The covet addition of aspartame to food and drink shouldnt be allowed to continue. If a food stuff which previously didn’t contain aspartame now does it should be splashed across the packaging. My wife is allergic to aspartame and sneaking it into food without advertising is dangerous.
This also removes consumer choice.

Linda Rostron February 17, 2019

I know that one day I am going to die from this body and return to spirit. While I’m in this body I want to enjoy life including delicious food and drink. I am not keen on artificial sweeteners, they have a strange taste/aftertaste. I much prefer a touch of honey, Manuka when I can afford it.

Jill Zarfati February 17, 2019

I am almost 76 and for at least 55 years I have not put sugar or any sweetener in my coffee which I drink without any kind of milk.
I occasionally eat cakes and biscuits, but prefer more savoury flavours.
So I can’t help with your question

Lin February 17, 2019

cut the natural sugars in drinks and food people will get used to having less sugar in cakes and sweets

Stella February 17, 2019

Very comprehensive article. I agree with other comments especially the need for fully independent research, as any funded by companies with a vested interest is bound to come out in favour of their product.

Joan sowton February 17, 2019

My concern is with vascular dementia.there have been good studies that prove the clogging of these in the brain could be added to by using artificial sweeteners.I have been diagnose in the last two this is a huge concern to me.I now have to have blood thinning medication. I like many people love my. Coffee and tea and drink about. 10 cups a day .sweetened with two aspartsmine based pills.I use artificial sweetener in cooking and custards .although I Dont have many fizzy drinks.but my first choice that I keep in my cupboard is Zero coke..I have been using these for over 40 years..and as I now are looking to help myself not lose anymore brain cells .when I saw this latest health scare. I truly thought this is me. And I threw everyone of the sweeteners in the bin.I am going to try the fruit based ones .I can’t say they are very nice .so maybe I can do without. But I will be using sugar in my cakes and custard and only having those as a treat at weekends. I am mortified a better study by our governments did not take place before allowing these poisons to be put into everyday food and drinks. I worry for our children .who we give this too to help with tooth decay and obesity that we are leading them into a different nightmare .im very concerned that no one can give me a reassurance from a reputable source.other than the big conglomerants who feed us with this stuff. I urge caution when using these sweeteners.

JaneB February 17, 2019

From the NHS site: “findings suggest artificial sweeteners “may have directly contributed to enhancing the exact epidemic [obesity and diabetes] that they themselves were intended to fight”.” … and they taste disgusting too …

Lynnette Roberts February 17, 2019

I found this article very interesting. I’ve always had concerns that artificial sweeteners do little to address what has become known as “Our sweet tooth”. As you say research and trials into diets and the huge industry that has grown around it are often misleading due in part to who has financed the study. Time to get of my high horse 😉

Mrs R Pegler February 17, 2019

This is one of the most sensible, comprehensive articles on health scare products that I have ever read. It gives all viewpoints and is very informative. If only every study and report could be as helpful as this one. Thank you.

Brian woulds February 17, 2019

Sweetners certainly do help with weight loss and I have been using them for years and also diet coke and the weight I’ve lost has certainly helped me not put ot back on

Judith Margaret Hayes February 16, 2019

More education on healthy diet choices is needed. I have seen people – especially teenagers – buying carb and sugar filled snacks plus a sugar-free drink. I’m sure they think that the low calorie drink will stop them putting on weight! So people need to understand that sugar-free drinks as part of a healthy diet is much better, plus plenty of exercise and at least 5-a-day veg & fruit.

Linda February 16, 2019

All I know is since I’ve developed ibs I’ve to avoid sugar free as sweeteners have an awful affect on my system

Victoria Simpson February 16, 2019

I firmly believe that the artificial ingredients regardless of what they are, if made in a factory more than 1 ingredient are bad for us! Naturally occurring, grown, and seasonal should be pushed and pushed through schools and for it to be cheaper to buy fresh meat, fish fruit and veg than ready made processed rubbish! I also think we need to look at more responsibly resources of meat and fish, and portion sizes of meat and fish!