Can you Coke until you choke?

"Don't try this at home. If you do, consult your doctor and a mental health professional."

This is the warning of George Prior, who is drinking 10 cans of Coca-Cola a day for a month to show his fellow Americans how much sugar they consume.

His website reads: So, you think I'm nuts? You think you're not drinking 10 Cokes a day?

"Add up some of your usual drinks and see how the sugar content compares. You may be surprised to find that you're just as insane as I am."

Prior claims 10 Coca-Colas are equivalent to the average level of sugar consumption in the US. He told The Times that Americans consume 70.7kg of sugar a year, according to the US Department of Agriculture. He said that is roughly equivalent to 200 g a day - t he sugar content of 10 Coca-Cola cans - and that he has put on 9kg after adhering to the "diet" for only 22 days.

"You can now dramatically see the effect that this very 'normal' amount of sugar has on a person," said Prior.

By The Times's calculations, the sugar content of 10 Coca-Cola cans is actually 390g, so the daily sugar consumption of the average American would actually be equivalent to five Cokes, half of what Prior claims.

Wits Public Health Professor Karen Hofman said: "One fizzy drink a day increases the risk of diabetes by 25%.

"In South Africa the number of new cases of diabetes has doubled in the last 10 years. We can't afford this.

"Aside from the terrible personal cost, the economic consequences for the country [are] huge. Treating people who get diabetes and its complications - such as blindness and the need to have their feet amputated - is costly."

Dietician Celeste Naude from the Stellenbosch Centre for Evidence said obesity, rather than sugar per se, was the primary driver of heart disease and diabetes. But she warned that sugar was often hidden in food.

She said: "Over the past three to four decades the food environment has changed dramatically with these aggressively marketed ultra-processed, highly palatable, energy-dense food products."

She said added sugars and sodium now dominate the contents of the food products people eat, especially in developing countries such as South Africa.