The public health lobby recently renewed its push for “sugar tax” on soft drinks, arguing it would help reduce obesity. “A tax on sugar sweetened beverages should be introduced as a matter of priority,” the Australian Medical Association (AMA) stated early in January. The doctor’s lobby group — fresh from their self-serving win in preventing Australians from buying codeine-based medication — argued that food producers and retailers are contributing to “overweight and obesity with associated health problems” and if those industries profess any commitment to nutrition, the “credibility of these statements is undermined by their lack of engagement around evidence-based interventions”.

The AMA has been cheered on by significant sections of the media, with Fairfax and the ABC providing positive coverage for a tax and suggesting any lack of interest from politicians — the government was quick to rule out a sugar tax — as the sinister product of the toxic lobbying power of Big Soda.

Problem is, it’s the AMA and the public health industry — a powerful, taxpayer-funded industry in its own right operating from academia and government health bodies — that refuses to engage with the evidence.

[Sugar tax unhelpful and unnecessary but try telling the nanny statists]

Let’s take Mexico, for example. It’s compulsory for journalists to mention Mexico when advocating a sugar tax, but the hard evidence from that country, which introduced a sugar tax on both beverages and foods in 2014, is that sugar taxes simply don’t work. Advocates of a sugar tax claim it produced a 6% decrease in soft drink purchases. Problematically, however, that conclusion is based on a survey of households and an assumed level of growth of soft drink purchases against which the survey results were assessed. In contrast, actual revenue data from the soft drink tax available from the Mexican finance ministry (available here) shows that sales only dipped by a negligible amount in the first year and then resumed climbing.

But even if sales did drop 6% in Mexico, and that drop was sustained, it hasn’t had any impact on obesity or diseases like diabetes in Mexico: both rose between 2012 and 2016 despite the 2014 imposition of the tax. That’s at odds with the ludicrously optimistic predictions of sugar tax proponents that it would save tens of thousands of lives and curb diabetes by 200,000 cases.

[Getting a sugar rush from controlling the poor]

While the public health industry might want to ignore the failure of the Mexican tax, it’s worth investigating just why it is that the sugar tax failed. One clue is provided by the Californian city of Berkeley: that city imposed a soft drink tax in 2015. Ostensibly, it was a win for nanny statists: the tax saw a 6 kilocalorie decline in soft drink consumption a day per capita. But intake of calories from untaxed beverages like milk and smoothies increased by nearly 32 kilocalories per capita. That is, the good citizens of Berkeley were consuming 25.5 kilocalories more from beverages, because to the extent they reduced soft drink consumption, they substituted other drinks, including some with greater calories.

Nanny statists appear to assume that once they increase the cost of soft drinks, consumers will obediently shift to water or diet drinks. While some do, it seems many more simply shift to untaxed drinks with high calorie content. That’s why there is no evidence from anywhere in the world that sugar taxes actually achieve public health benefits.

NEXT: We’re fat because we consume too much sugar? Not so fast, sweetie.