A Windsor chef estimates that 30 per cent of the food he serves ends up being scraped into the garbage.

"Most people don’t eat everything on their plate," The City Grill’s executive chef, Shawn McKerness, said.

That’s what the Cut Waste, Grow Profit draft report from the Ontario-based Value Chain Management Centre found. It suggests that more than half (51 per cent) of the estimated $27 billion of food wasted countrywide ends up as unwanted leftovers.

"A lot of people just don’t eat leftovers." McKerness said.

However, there isn’t much he can do about the waste. Once it’s paid for, it makes no difference to the restaurant’s bottom line.

But McKerness said he has to make portions big enough to provide for leftovers — even if customers routinely scrap them. He said diners want "good bang for their buck" when they sit down to eat.

"A lot of Windsorites like to see a lot of food on their plate. If they don’t, they don’t come back," he said. "In order to impress a lot of guests, you have to have the wow factor. If they don’t feel that value, they’re not going to come back to the restaurant."

McKerness said food is often better the next day.

"Lasagna, for example, is a great leftover food," McKerness said.

The Cut Waste, Grow Profit draft report found that expectations for larger portion sizes, confusion about safe consumption and sell-by dates, and the low cost to households of over-purchasing and wasting food were among factors blamed for the wasteful behaviour.

Grant Baldwin, director of the documentary Just Eat It: A Food Waste Story, said expiration dates are set "extremely conservatively" and food can be safely consumed for months, sometimes years, after the date.

He also said that 25 per cent of the food Canadians buy at the grocery store ends up uneaten and in the trash.

"And it’s not food scraps we’re finding. We’re finding packaged items, the kind of stuff you’d see stored," he said. 

According to another report published earlier this year, more Canadians are making an effort to eat their leftover food.

A report prepared for the Canadian Grocer, a trade magazine for grocers, found more Canadians are eating more leftovers at lunch now than six years ago.

According to the study by NPD Group, 22 per cent of Canadian lunches included a leftover. In 2011, 28 per cent did.