Gyms may be closed thanks to lockdowns, but that hasn’t stopped the Australian government from lecturing its citizens about our waistlines. Policymakers are considering taking a page from Britain’s book and bringing in the nanny state to combat the obesity crisis. From sin taxes to advertising bans, British public health policy has become a manual for how to fail at making a nation healthier – and consign civil liberties to the garbage truck in the process. 

The first of these disastrous policies was the soft drinks sugar levy, introduced in 2018 by then- prime minister Theresa May in an effort to put...