Purchasing sugar-sweetened beverages (SSBs) is becoming increasingly common and accessible. Excessive buying of these beverages has been linked to various health issues, including an increased risk for dental caries, weight gain, obesity, hypertension, diabetes, and cardiovascular diseases (Tappy and Lê, 2010; Te Morenga et al., 2013; Te Morenga et al., 2014). Recent research has revealed that the addictive properties of sugar and its potential to disrupt normal satiety signaling leads to increased sense of hunger and overeating behaviors (Lustig et al., 2012; Lustig, 2010; Crawshaw et al., 2021).

Implementing a sugar tax has emerged in public health policy discussions as a strategy to combat the adverse effects of excessive sugar consumption. Earlier studies have demonstrated that implementing or increasing of SSB taxes leads to a reduction in the average SSB purchases (Colchero et al., 2016; Sturm et al., 2010) and sugar intake (Sánchez-Romero et al., 2016; Kao et al., 2020). However, the evidence from Asia is currently weak (Basu et al., 2014a; Cabrera Escobar et al., 2013; Cobiac et al., 2017; Silver et al., 2017). Hattersley and Mandeville (Hattersley and Mandeville, 2023) highlighted that national SSB taxes in 2023 only affected 10% of the population in East Asia and the Pacific region. Recent studies in two Asian settings, namely, Singapore and urban Vietnam, reported high public support for an SSB tax to reduce sugar intake, but did not examine its impact on purchase habits or population health (Tan et al., 2021). Considering that the impacts of policy interventions to reduce sugary drink purchase are influenced by the type of intervention, its public acceptance, and the specific context (Promberger et al., 2012), investigations employing Asian populations were warranted to offer broader generalizations and a more comprehensive understanding of the potential impact of SSB taxes.

Hong Kong, an affluent setting in East Asia with a per capita GDP of US$44481.34 in 2021 (Census and Statistics, 2023), faces a 39% population that is overweight (Clark et al., 2021; Ko et al., 2010). The average daily sugar intake in Hong Kong exceeds recommended level by the World Health Organization (WHO), with approximately 32% of total sugar purchase coming from non-alcoholic beverages, including non-diet soft drinks (Wagner et al., 2021).

Given these concerns, the Department of Health in Hong Kong has expressed interest in introducing an SSB tax to address health issues associated with sugar purchase. However, evidence is required to determine the optimal rate, scope, and impact of such a tax (Thomas et al., 2021). Hence, we conducted a cross-sectional study to examine SSB purchase habits in Hong Kong and whether and at what tax rates an individual intends to reduce their SSB purchase (“willingness to pay” (WTP)). Based on the WTP data, we further conducted a simulation study to assess the long-term impact of SSB taxes on the prevalence of obesity/overweight and type 2 diabetes mellitus (T2DM). We hypothesize that an introduction of SSB tax is likely to decrease the prevalence of overweight/obesity and T2DM based on the WTP pattern in Hong Kong. Considering the similarities of food habits and income levels across Asia Pacific, this study's findings are expected to provide crucial evidence that can assist policymakers in making decisions regarding the most effective and equitable tax rate on SSBs, that effectively address public health concerns related to overweight/obesity and T2DM, considering the socioeconomic factors specific to the region.