Professor Doug Sellman of the National Addiction Centre said all soft drinks and unhealthy foods should be marked red under a 'traffic light' food labelling system.
He compared companies selling those foods without warning labels to drug dealers.
"This is being very strongly resisted by the food industry. It's a bad idea if you're into drug dealing. It's just a good idea if you're into health."
Food and Grocery Council chief executive Katherine Rich said comparing food companies to drug dealers was unfair and offensive.
"Professor Sellman is undermining his credibility with these kinds of comments. To refer to a food company as a drug dealer is patently absurd."
A traffic light system labelling foods for fat, saturated fat, sugar and salt content would be confusing for consumers, she said.
Information from the Australian Food and Grocery Council showed that system would give milk amber lights for fat, saturated fat and sugar, while soft drinks only got one red light for sugar, she said.
"It doesn't work and it ends up sending out very confusing messages.
"The truth is there would not be a warning label on the planet that would have dealt with this extreme consumption. You can't label for extremes."
Professor Sellman said while Ms Harris' case was "extreme", there were thousands of people across New Zealand who were addicted to soft drinks and energy drinks.
He had encountered many people who drank up to five litres of soft drink a day.
Young people were particularly vulnerable to addiction to energy drinks such 'V', he said.
"There are enormous health impacts from the use of what's being sold as legitimate food but it's not good food. A lot of the deaths in New Zealand are the result of addictive behaviour and part of that is food addiction."
Addictive foods and drinks usually contained high amounts of sugar and fat and a "psychoactive" substance such as caffeine, Professor Sellman said.
Addicts such as Ms Harris would start out with low level consumption and build up over time, he said.
"They It's like the tide. It comes in and then suddenly you realise it's high tide."
University of Otago researcher Lisa Te Morenga said the sheer volume of water Ms Harris was consuming in the 10 litres of Coca-Cola she was drinking could have been more toxic than the huge levels of sugar and caffeine.
A person consuming up to 10 litres of any liquid a day would severely put their health at risk, Dr Te Morenga said.
"Even drinking that much water a day would be detrimental, as our maximum capacity for water is something like 4 litres a day. I certainly wouldn't recommend it,'' she said.
Dr Te Morenga is leading a Dunedin study of people who consume large quantities of sugary drinks and the corresponding risks of them developing diabetes and obesity.
She said aside from death, adverse health effects of consuming so much soft drink included diabetes and obesity.
"For someone who has a habit like that, it's definitely an addiction,'' she said.
A Coca-Cola Oceania representative, who was in the coroner's court as an observer, told the inquest the company did not believe there was any basis for finding the consumption of Coke caused Ms Harris' death.
"We deeply sympathise with the tragic death of Ms Harris, but we are firmly of the view her death was not due to the purchasing of Coca-Cola."
She said medical evidence referred to other contributing factors and the "possibility rather than a probability" of the role Coke played.
Evidence on how much Coca-Cola Ms Harris drank varied. Her partner, Chris Hodgkinson, at one point claimed it was 10 litres a day, and at another point said it was five 1.5 litre bottles each day.
Other witnesses said Ms Harris would drink upwards of 4 litres of Coke a day and police said 7 litres a day was a mid-range figure of her consumption.
EXPENSIVE HABITS
7.5 litres a day
@ $1.50 per 1.5l bottle*
= 5 bottles per day
= $7.50 per day
= $2737.50 per year
* Based on $3 for two on special at Countdown yesterday
Plus ...
30 cigarettes
@ $13.60 a pack of 20
= $20.40 day
= $7446 a year
