If you want to lose weight, watch the portions you dish out on your plate.

That’s one of the messages the Dietitians of Canada (DC) will be focusing on during nutrition month in March.

Recent surveys indicate that close to half of adult Canadians are overweight and one in six is obese.

“Portion sizes are a huge issue,” says Heidi Bates, a registered dietitian from Edmonton. “We have seen the portion sizes of some foods really grow over the last 20 years. And bigger portions mean more calories.”

For example, a 30.5-cm (12-inch) submarine bun equals six servings of grain products, half of the Canada’s Guide to Healthy Eating recommended five to 12 daily servings. For someone who’s not very active, it’s an entire day’s worth of grain products.

“We have just gotten used to restaurant and food services serving portions that are really quite large,” says Bates, “so we visually come to know it as being a portion size when in fact we are probably eating two portions now.”

People tend to think they are getting more for their money and lose sight of standard portion sizes, says Bates. A common restaurant portion size of spaghetti is 750 ml (3 cups), when the standard portion is 125 ml (? cup).

As part of the nutrition month campaign, dietitians are presenting the Healthy Way Challenge - a new challenge each week in March - on their website, http://www.dietitians.ca/eatwell.

Bates says there’s not one specific reason that Canadians are gaining weight.

“It would be very simplistic to say bread or pasta is the culprit like some diet books try to tell us,” she says. “But really it is a whole bunch of lifestyle habits including physical inactivity.

“Look at the way we live. We can drive through just about everything, from dry cleaning, banking (and getting) food, and never leave the comfort of our vehicle.

“We have created communities where you have to pretty much have a car because all the services are located in one place and all the residences are located in another.”

Another nutrition initiative for March has brought together the Dairy Farmers of Canada and Breakfast for Learning, a non-profit organization that supports child nutrition programs across the country, to launch a nutrition game.

Mission 5522 refers to the minimum number of servings of each food group recommended by Canada’s Food Guide. Healthy eating includes five servings of grain products, five servings of vegetables and fruit, two servings of milk products and two servings of meat and alternatives each day.

The game has pirate-themed activities featuring nutrition-related puzzles and brain-teasers that take kids on a quest to unlock the secret code to healthy eating.

“We know there is a gap between what kids know and the foods they choose,” says Kathy Furgala, a Toronto dietitian.