Mexican obesity 180Two years after the Mexican government introduced a tax on sugary drinks, the country's residents continue to consume more carbonated drinks per person than any other nation and have one of the world's highest rates of childhood obesity.

According to latest research each Mexican gets through an estimated 163 litres (36 imperial gallons) on average per person every year - 40% more than an average American (who drinks 118 litres, or 26 gallons).

In January 2014, Mexico introduced a national tax on sugary drinks and junk food - a 10% tax on every litre of sugar-sweetened drinks and an 8% tax on high-calorie food. The effect of these on children is a particular concern - according to Mexico's Health Ministry, the country leads the world in childhood obesity.

Dr Salvador Villalpando, a childhood obesity specialist at the Federico Gomez children's hospital in Mexico City told the BBC: "About 10% of kids are being fed soda from zero to six months of age. By the time they reach two it's about 80%."

According to research by Mexico's National Institute of Public Health, together with the University of North Carolina, in the first year the tax reduced consumption of sugary drinks by an average of 6% over the 12 months, reaching 12% by the month of December. In the poorest housholds, monthly purchases of sweet drinks fell by a full 17%.

However Jorge Terrazas of Mexico's bottled drinks industry body, Anprac argues that fizzy drinks only account for 5.6% of Mexico's average calorie consumption so can only be a small part of the solution to obesity and diabetes.

No data has yet been published that would indicate whether the tax is having an effect on Mexicans' health. But Dr Miguel Messmacher, under-secretary of revenues at Mexico's Ministry of Finance, says he is in no doubt that it is working.

"We've raised close to 20bn pesos (£760m)," he said. "It's a fairly significant amount. I think the results we have so far have led to the changes in behaviour we wanted."

In October a report by Public Health England recommended a tax of between 10% and 20% on high-sugar products as one measure needed to achieve a "meaningful" reduction in sugar consumption. Food Standards Scotland has also recently proposed a sugar tax.

Join the debate on obesity at our upcoming conference 'The 2016 Childhood Obesity Framework - Tackling the epidemic from a child’s first 1,000 days onwards' (15 June, London)