Drinking fizzy water may boost weight loss by boosting glucose uptake and metabolism, a study suggests.
The carbonated beverage has been hailed as a potential slimming aid as it can make you feel full, curb hunger pangs and reduce blood glucose levels.
Now, Japanese expert Dr Akira Takahashi, from the dialysis centre at Tesseikai Neurosurgery Hospital, has put forward a theory for exactly how these physiological effects are achieved.
His research compared the process of drinking fizzy water with haemodialysis, a treatment that involves filtering blood to remove waste and excess fluid when the kidneys are not working properly.
Haemodialysis turns blood alkaline, primarily producing carbon dioxide.
Similarly, the CO₂ of fizzy water is absorbed through the stomach lining and rapidly converted to bicarbonate (HCO3) in red blood cells.
Dr Takahashi said the alkalinisation process speeds up glucose absorption and use by activating key enzymes in red blood cells, which may explain how drinking fizzy water aids weight loss.
But he noted that it was “not a standalone solution for weight loss”. The researcher added: “A balanced diet and regular physical activity remain crucial components of sustainable weight management.
“Also, drinking carbonated water can have some effects on the digestive system, particularly for individuals with sensitive stomachs or pre-existing gastrointestinal conditions.
“Moderation is key to avoiding discomfort while still enjoying the possible metabolic benefits of carbonated water.”
The findings were published in the journal BMJ Nutrition Prevention & Health. However, Professor Keith Frayn, an emeritus professor of human metabolism at the University of Oxford, was not convinced by the theory.
He said: “I am sceptical of the claimed mechanism. If fizzy drinks were to be shown to lead to weight loss, it would much more likely be through effects on feelings of fullness.
“In the meantime, however, sugar-sweetened fizzy drinks are recognised as a source of excess calories and likely to do just the opposite.”
