Justin King has launched an astonishing tirade against advocates of front-of-pack GDAs, describing the food and drink industry's failure to engage with the health and obesity agenda as "disgraceful".

The Sainsbury's CEO, who infuriated the industry when the retailer became the first to adopt the FSA's traffic lights, reopened old wounds when he described FDF-endorsed GDAs as "dishonest" at last week's CIES World Food Business Summit in New York.

"It's interesting that food manufacturers are railing against multiple traffic lights," he said. "They don't believe traffic lights add anything and are using GDAs front-of-pack even though they've been back-of-pack for 10 years and haven't made a difference.

The use of colour-coded GDAs was disingenuous, he said. "If you don't believe colour makes a difference, don't use it. Putting those panels on the front of cereal using green is dishonest. Put it in black and white. If you didn't think colour communicated anything, you wouldn't use blues and greens. No-one is using red. I wonder why."

The industry was not doing enough to tackle obesity, he added. "It's disgraceful, frankly, that the industry's not engaging with these issues. If we don't, we will reap what we are currently sowing," he said.

Calling on the industry to market products "in an honest, open and engaging way", King urged it to first acknowledge the problem. "We won't get the opportunity if we continue to sit in a place of denial," he said.
The UK diet had gone into a "50-calorie deficit", he said, with people consuming 750 fewer calories a day but expending 800 fewer through exercise. "Fifty calories a day deficit in your diet, you'll put on a pound a month, a stone a year and go from fighting fit to clinically obese in two years."

Manufacturers and rivals dismissed his comments, which came just days before US health and obesity experts sent a letter to President Barack Obama urging him to introduce an anti-obesity strategy similar to the UK's Healthy Weight, Healthy Lives policy launched last year.

"We know that front-of-pack GDAs make a difference and a recent report by the FSA made this exact point when it said GDAs were widely understood and used by customers," said a Tesco spokeswoman. "GDAs provide the most accurate, consistent and factual information and research shows they better enable customers to make informed decisions."

Traffic lights were confusing, said Rachel Fellows, Kellogg's UK corporate communications manager. "We use GDAs as they give consumers the nutritional composition of a product per portion," she said. "Traffic lights judge the nutrition credentials of a food on a 100g portion more than three times the average serving of our cereals."