The Surprising Link Between Sparkling Water, Metabolism, and Weight Loss

It could help, but no miracle cure

By BMJ Group

A new analysis published January 22 in BMJ Nutrition, Prevention & Health suggests that sparkling soda water may support weight loss by slightly enhancing blood glucose uptake and metabolism—the process by which the body converts energy. 

However, the effects are minimal, meaning carbonated water alone is not a reliable solution for shedding pounds.

According to the author, there are no shortcuts to effective weight loss. Regular physical activity and a well-balanced diet remain essential, and the long-term effects of consuming large amounts of fizzy water are still unknown.

Potential Mechanisms of Soda Water

Sparkling water is often considered a potential weight-loss aid because it can create a feeling of fullness, helping to curb hunger, and is thought to speed up digestion and lower blood glucose levels.

However, the author emphasizes that the exact mechanisms by which carbonated water might reduce blood glucose levels and support weight management are not yet fully understood.

To try and find out, the author compared the process of drinking fizzy water with hemodialysis, whereby blood is filtered (dialyzed) to remove waste and excess water when the kidneys no longer can, drawing on previously published research.

Comparative Analysis with Hemodialysis

Hemodialysis turns blood alkaline, primarily producing carbon dioxide (CO₂). Similarly, the CO₂ of fizzy water is absorbed through the stomach lining and is rapidly converted to bicarbonate (HCO₃) in red blood cells. This alkalinization process speeds up glucose absorption and use by activating key enzymes in red blood cells, explains the author.

Clinical observations during hemodialysis show that blood glucose levels fall as blood passes through the dialyzer, despite a higher glucose level in the dialysate solution to start with, he adds.

Minimal Impact on Weight Loss

While these findings suggest that fizzy water may indirectly promote weight loss by enhancing the uptake and use of blood glucose, context is key, emphasizes the author.

During a typical 4 hour hemodialysis session around 48000 ml of blood flows through the dialyzer, resulting in around 9.5 g of glucose being used during the session, he explains.

“Given this minimal glucose reduction, the impact of CO₂ in carbonated water is not a standalone solution for weight loss. A balanced diet and regular physical activity remain crucial components of sustainable weight management,” he insists.

“Also, drinking carbonated water can have some effects on the digestive system, particularly for individuals with sensitive stomachs or pre-existing gastrointestinal conditions. The primary concerns include bloating, gas and, in some cases, exacerbation of certain symptoms associated with digestive disorders, such as irritable bowel syndrome or gastro-oesophageal reflux disease,” he points out.

Conclusion and Expert Commentary

“Moderation is key to avoiding discomfort while still enjoying the possible metabolic benefits of carbonated water,” he says.

Commenting on the analysis, Professor Sumantra Ray, Executive Director, NNEdPro Global Institute for Food, Nutrition and Health, which co-owns the journal, said: “While there is a hypothetical link between carbonated water and glucose metabolism this has yet to be tested in well designed human intervention studies.

“And although this study adds to the evidence base, it doesn’t provide sufficient evidence on which to make recommendations for the preventive or therapeutic use of carbonated water. Additionally, any potential benefits must be weighed up against the potential harms of carbonated drinks which may contain sodium, glucose, or other additives.”

Reference: “Can carbonated water support weight loss?” by Akira Takahashi, 21 January 2025, BMJ Nutrition, Prevention & Health.
DOI: 10.1136/bmjnph-2024-001108