Childhood obesity is a ticking time bomb for our health system. It is related essentially to diet. There is no convincing evidence that activity levels in children has changed. The issue is complex but the "low-hanging fruit" is fizzy drinks. As long as the tax goes towards something useful rather than disappearing into the consolidated fund people will support it. In Mexico the tax went to providing quality water in schools. Perhaps in NZ it could go towards providing healthy school lunches. In Mexico the tax on sugar sweetened beverages was associated with reductions in purchases of taxed beverages and increases in purchases of untaxed beverages. This research was published in the British Medical Journal. Of course the Industry disputes this, but I would rather trust the independent research.