Still or sparkling water for the table? It’s a polarising question. Some simply hate the carbonated cousin of the flat stuff. But what it does to our digestion is also a source of contention.
There was a theory which circulated on social media that fizzy water increases appetite, an argument which finds its roots in a limited study on, er, male rats.
Now though, the tide might be turning in favour of water with fizz, thanks to the results of a new study about its effects on blood glucose levels. And in times when many are monitoring their blood sugar spikes with devices such as the Zoe, it’s been enough to pique serious interest.
The findings of the research by Tesseikai Neurosurgery Hospital in Japan argue that carbonated water could lower blood glucose, which could in turn be beneficial for the metabolism and therefore aid weight loss.
It points to the fact that carbon dioxide in the water could speed up the absorption of glucose when it is taken up by red blood cells. And as this has the effect of minimising spikes and dips in blood sugar levels, the body’s cells might more effectively burn fat between meals for energy.
However, other experts have thrown the findings into question, with further research published in the journal BMJ Nutrition Prevention & Health by Dr Akira Takahashi noting that: “While many advocate for its benefits, it is important to explore the underlying mechanisms more closely.”
The original paper suggests that haemodialysis (a common type of dialysis) turns blood alkaline, primarily by producing carbon dioxide. Similarly, the Japanese researchers said, the carbon dioxide in fizzy water is absorbed by the stomach and into the bloodstream. This alkalinisation process speeds up glucose absorption, they claim.
But professor Keith Frayn, emeritus professor of human metabolism at the University of Oxford, says: “I am sceptical of the claimed mechanism. Even if it were possible to show that the carbon dioxide in fizzy drinks increases the use of glucose by red blood cells, that will not necessarily lead to weight loss. Red blood cells cannot fully ‘burn’ the glucose and it will be recycled by the liver.” Other experts confirmed there is far from enough evidence to test such a hypothetical link, which would require testing in well-designed human intervention studies.
So are there any benefits to glugging carbonated water beyond the enjoyment of added fizz? Dr Liza Osagie of SOLICE Health tells The Standard: “While fizzy water may temporarily reduce hunger by providing a sense of fullness, it’s not clear its long-term effects as a weight loss strategy.”
Dr Osagie advises that even if the alkalinisation is occurring, don’t expect to see palpable results. “Studies have indeed suggested that fizzy water might aid weight loss by boosting blood glucose uptake and metabolism — the rate at which the body uses and converts energy — but the effects are so small, drinking it can't be relied on alone to shed the pounds.”
Nutritionist Stephanie J. Moore is also dubious. “It could be that if someone drinks fizzy water rather than no water at all, they will benefit a little from some hydration, which does help metabolism and can reduce hunger, otherwise, this sounds like nonsense!”
Moore warns that tricking the body is never wise, and there could even be some downsides: “Fizzy water can cause abdominal bloating, which can suppress appetite, but again, not an ideal way to be controlling food intake.” Another undesirable side-effect of drinking too much of the stuff? “Fizzy drinks can cause or exacerbate reflux, especially if consumed during or after meals.”
For those looking to lose weight, the experts advise the good old fashioned, sustainable approach. “Weight management is far more complex than curbing hunger pangs; it requires a holistic approach that includes balanced nutrition, physical activity, and emotional wellbeing,” Dr Liza implores.
What does this look like in 2025? “Personalised nutrition plans, integrating real, whole foods tailored to individual metabolic needs. Combining this with mindful eating, resistance training, and high-intensity interval training (HIIT) ensures fat loss while preserving muscle mass. Behavioural interventions, such as habit tracking and stress management, remain crucial for lasting results. Emerging tools like wearable tech and continuous coaching and support from experts ensure sustainable progress.”
In short there is no quick fix, and glugging back gallons of fizzy water will likely leave you feeling worse for wear rather than thinner.
