Background
Excess sugar consumption has been linked to numerous negative health outcomes, such as obesity and type II diabetes. Reducing sugar-sweetened beverage (SSB) consumption may reduce sugar intake and thus improve health. The aim of the study was to test the impact of the potentially different rewarding nature of water or diet drinks as replacements for SSB, using a habit and implementation intention–based intervention.

Method
An online randomised, two-arm parallel design was used. One hundred and fifty-eight participants (mainly from the UK and USA) who regularly consumed SSBs (Mage = 31.5, 51% female) were advised to create implementation intentions to substitute their SSB with either water or a diet drink. Measures of SSB consumption, habit strength and hedonic liking were taken at baseline and at 2 months. Water or diet drink consumption was only measured at 2 months.

Results
There was a large and significant reduction in SSB consumption and self-reported SSB habits for both the water and diet drink groups, but no difference between groups. There were no differences in hedonic liking for the alternative drink, alternative drink consumption and alternative drink habit between the two groups. Reduction in SSB hedonic liking was associated with reduced SSB consumption and habit.

Conclusion
This study demonstrates that an implementation intention–based intervention achieved substantial reductions in SSB consumption and habits. It also indicates that hedonic liking for SSBs and alternative drinks are associated with changes in consumption behaviour. Substituting SSBs with water or diet drinks was equally as effective in reducing SSB consumption.