I have a demon sweet tooth and don’t mind the odd fizzy, sugary drink. I’ve started opting for sugar-free alternatives but have heard some scary claims such as these being linked to weight gain and disease. I was wondering whether I am actually better off drinking the sugar-filled versions. I can just hear my doctor asking “what’s wrong with water?” but sometimes I can’t resist! — Tilly
On a hot day, there’s nothing like the sweet, bubbly hit of a fizzy drink to quench your thirst.
But while it’s well known that sugary soft drinks are bad for your health, there’s also a fair bit of scepticism around about drinks that are sweetened with things that aren’t sugar.
So are diet soft drinks better for you, or even worse than the sugar-filled original versions? Let’s take a look.
What are sugar alternatives made from?
The chemicals that give diet fizzy drinks their sweetness do so by interacting with the same parts of your mouth that sense the sweetness in sugar.
Spoon for spoon, many of these sweeteners have similar energy to sugar, but they’re hundreds or thousands of times sweeter than sugar.
That means you only need to use a fraction of the amount to get the same sweetness hit, so the kilojoules in your drink become negligible.
Some of these sweeteners, such as aspartame and sucralose, are “artificial”, in that they are manufactured using chemical processes.
Others, such as stevia and monk fruit extract, come from plant sources, although they generally undergo significant processing before ending up in your drink.
Just because some sugar-free sweeteners come from “natural” sources doesn’t make them better, said Emma Beckett, a nutrition scientist at the University of Newcastle.
“There’s this idea that ‘natural’ is better for you. But, you know, poisons are also natural. Quite often coming from plants.”
Is there any evidence they cause health problems?
Not really. There have been claims that sugar-free sweeteners have been linked to diseases such as cancer, but these are based on very thin, outdated evidence.
Because of the miniscule amounts of these chemicals that are required to sweeten soft drinks, the risk of them causing disease is also vanishingly small.
Aspartame in particular is one of the most exhaustively studied substances around.
“In the amounts we consume them, there’s no evidence of harm and they are very tightly regulated,” Dr Becket said.
“People really should not worry about things that are approved for use. It is quite rigorous, they constantly review the evidence behind their safety.”
What’s with the link between diet drinks and weight gain?
There have been studies that have shown links between all soft drinks — both sugary and diet ones — and increased risk of death, especially from cardiovascular disease.
But a link doesn’t necessarily imply cause and effect.
“Say [a study finds] overweight women are more likely to drink Diet Coke,” Dr Beckett said.
“Does Diet Coke make women overweight? Or are overweight women more likely to choose Diet Coke in the attempt to lose weight?
“It’s very hard to unpack those observational studies in terms of causation versus just correlation.”
However, there are some experts who think there might be something about sugar-free sweeteners that encourages people to gain weight.
It might just be that people subconsciously eat more because they’ve already been “good” by choosing a diet drink. Or it might be something else happening inside the body.
“There’s lots of theories about the microbiome and how that might change with artificial sweeteners or how you might confuse the satiety centres in the body when you have that sugary taste,” Dr Beckett said.
There could be a problem if no energy hit follows up the sugary taste.
“That could have consequences for appetite and driving you to eat more.”
Are sugary soft drinks really that bad?
They’re certainly not great for you. There is strong evidence for the advice to limit the amount of free sugars in your diet — that is, those sugars added to foods and drinks, or naturally found in honey, syrups and juices.
Reducing sugar intake helps maintain a healthy body weight, protecting against many diseases, and is also better for your teeth.
So while water is the best option if you’re looking for a drink, a diet soft drink is preferable to a sugary one,” Dr Beckett said.