Taxing high-calorie or lower nutritional quality foods would reduce France’s growing obesity problem, a study released by a government agency has concluded.

The report argued obesity cost France EUR20.4bn (US$22.73bn) in healthcare costs in 2012 – with 15% of the population obese and 32.3% overweight.

Drawing on the experience of a tax on high-calorie food imposed by Mexico in 2014, the Trésor agency said: “Nutritional taxes are the only method where the economic gains in health cost savings exceed the price of implementation.”

However, to be effective, the tax must be set at the right level, the report said. It cited a US study where imposing a tax 1-8% of the product price did not reduce sales, while a 33% tax led to 3.5% less consumption.

The study also suggests increasing the value-added tax on products “most harmful to health”.

Emphasising the levy must not disadvantage lower-income families, which consume more junk food, the agency added “there is nothing to stop a redistribution measure…” being added to compensate this tax.

The Trésor also proposed giving health professionals more money to fight obesity, “re-orientating” consumers towards healthier choices – for example cutting portion sizes and putting fruit instead of crisps in vending machines – upping the number of obesity prevention campaigns, stopping or banning all junk food adverts aimed at children and more “anti-obesity” nutritional labelling.