Carbonated Water Cuts Alcohol and Snacking

A daily glass of sparkling water reduced snacking by 1.5 times per week and trimmed alcohol intake by 24 grams, and improved liver enzymes.

STUDY: Hashimoto H et al, Scientific Reports 2026; 

STUDY TYPE: Randomized controlled trial

FUNDING: Asahi Soft Drinks Co., Ltd. Two of the five authors are Asahi employees.

Background

Carbonated water may reduce appetite by distending the stomach, slowing gastric motility, and producing a sense of fullness. Most prior evidence comes from short-term lab studies. This trial tested it in the real world.

The Study

• 46 healthy Japanese adults (ages 20–64, body mass index 23–30) who habitually snacked and drank alcohol at least weekly
• Randomized to 500 ml/day of carbonated water vs. plain water for 12 weeks
• Outcomes: snacking frequency, alcohol intake, body weight, BMI, and blood chemistry

Results

Snacking dropped more in the carbonated water group, by about 1.4 fewer times per week at week 4 (moderate effect, Cohen’s d = 0.73) and 1.5 fewer times per week at week 12 (Cohen’s d = 0.61), compared to the plain water group.

Alcohol intake fell by 24 grams per week more in the carbonated water group at 12 weeks — roughly two standard drinks, with a moderate effect size (Cohen’s d = 0.73).

Body weight dropped 0.72 kg more and BMI 0.26 kg/m² more in the carbonated water group at week 12. Liver enzymes also improved: AST fell 4.1 U/L more and ALT fell 9.5 U/L more versus plain water. These enzyme values stayed within normal range throughout.

Side Effects

No adverse events were attributed to the carbonated water. Adverse event rates were similar in both groups (26% carbonated vs. 35% plain water), with only transient events like headaches and cold symptoms.

Limitations

Small, open-label, industry-funded, not correction for the many outcomes tested, and several p-values barely crossed 0.05

Practice Implications

1. Take this study as a plausible signal, not proof.
2. If you or your patient is trying to cut back on snacking or evening drinks, swapping in carbonated water is an easy behavioral substitution worth considering.