AIM: This study quantified associations between (absolute and relative) individual income and obesity prevalence. These associations were then used to model the potential effect of a New Zealand (NZ) Government's income redistributive policy (the Families Package) on adult obesity prevalence.
METHODS: Logistic regressions were used to investigate associations between absolute individual income and adult obesity prevalence in NZ. Linear regressions were used to assess associations between relative income (income inequality measured by Gini) and obesity prevalence (from the NCD-RisC) for OECD countries. Potential impact fractions were calculated to determine how income redistribution might affect obesity prevalence.
FINDINGS: Absolute individual disposable income was significantly associated with obesity in NZ females (but not males) in a shallow, inverted J-shaped fashion. Income inequality was significantly positively associated with obesity prevalence in NZ females but not in males. The Families Package had a modest effect on income distribution and reduced Gini in NZ by 1.43%. Female obesity prevalence in NZ was modelled to decrease by 0.12 percentage points and 0.98 percentage points due to changes to absolute income and income inequality, respectively.
CONCLUSIONS: Despite being the most substantial income tax package in New Zealand since the 1990s, this policy had a modest effect on income redistribution, and its expected impact on reducing obesity in females was also modest, with no effect in males. The J-shaped curve indicates that income redistribution could even increase obesity prevalence among low-income women.