The heads at Sainsbury's, Morrisons and the Co-op told The Times they ignored both sell-by and best-before dates, while executives from Tesco, Waitrose and Marks & Spencer disregarded use-by dates.
It comes as campaigners argues that millions of tonnes of food is wasted or thrown away each year in the UK because of confusion among consumers over when food is no longer safe to eat.
Dalton Phillips, chief executive of Morrisons, said he used a "smell test" rather than official expiry dates for much of his food.
He said: "Meat especially... I would smell it. Our date codes in the UK are pretty strict. But good, aged beef is nicer. I am always going over the date on my yoghurts. A sell-by date for lots of cheese is ridiculous - they get better with age. The rule is, smell it."
Mark Price, managing director of Waitrose, added that he often ate fruit, vegetables, cheese, meat, sausages and bacon "a day or two after" the use-by date.
Last year Tesco said it threw away almost 30,000 tonnes of food waste in the first six months.
Government figures this week showed that the average weekly spending on all household food and drinks in 2012 was £29.29 per person, an increase of 4.6% on 2011.
Food was the largest item of household expenditure for poor households after housing, fuel and power costs.
The average family could save £60 a month by reducing the amount of food it throws away, campaign group Love Food Hate Waste said.
Mary McGrath, from the charity Foodcycle, said: "Simpler and more accurate expiry dates would help consumers and supermarket bosses alike. We are wasting shocking amounts of perfectly edible food every day. I would have to question what they are doing about food waste."
Best-before dates are intended to advise customers on when a food product may be past its best but still safe to eat, guidance from the Food Standards Agency says.
Use-by dates are meant to show when food is no longer fit to eat, while sell-by dates are used in some shops as instructions to staff to help with stock control.