Healthy foods are cheaper than junk food, so why are we so fat?

If you've always maintained you'd buy healthier food if it just cost less, you may be in for a surprise.

A recent USDA study challenges the notion that junk food is less expensive than fruits, vegetables and whole grains, decimating a popular excuse for many who choose less healthy options.

The issue at stake is that in the past researchers had measured the cost of food on a price per calorie basis. This means that a small bag of chips — which would be higher in calories, sodium and saturated fat — would get you more bang for your buck than, say, a cup of broccoli, which is the recommended serving size for broccoli.

But TIME argues that North Americans needn't be concerned with consuming enough calories — our problem is quite the opposite. Therefore when you compare serving size with serving size, the broccoli becomes the more cost-efficient option.

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However, Canadian experts on nutrition and obesity eye the new study with caution. Our obesity epidemic is far more complex than just comparing apples with orange-coloured "cheez snax," they say. For instance, the time it takes to cook a healthy meal versus grabbing fast food, may be a factor for many families, says Calgary-based obesity expert Dr. Arya Sharma.

"Just compare the time and effort it takes to walk into a fast food restaurant and grab a hamburger or even a salad versus having to go and shop for the ingredients, take them home, prepare them from scratch, and serve them," he argues."And don't forget the time it takes to clean up the mess and wash the dishes."

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Sara Kirk, the Canada Research chair in Health Services Research at the School of Health and Human Performance in Halifax makes the point that processed foods are heavily marketed and readily available, whereas fruits and vegetables are less available and more perishable, making them difficult for stores to sell.

She agrees that convenience frequently wins out over cost and that people must be equipped with the skills necessary to identify healthier options and know how to cook them, in order for things to change. Food insecurity is also a factor, she says.

"If you are on a low income and can choose between an apple and a large bag of chips to keep you or your child from feeling hungry, the chips would win out as they are more satiating," says Kirk. "This is a real issue in Canada, where income-related food insecurity affects more that 2 million Canadians."

Environment must also be considered when examining food choices, says Shelly Russell-Mayhew, a professor in University of Calgary's Psychology Department and expert in health psychology.

"If there are no grocery stores within walking distance, or it is not safe to walk in a neighbourhood, then fruits and vegetables, whether cheaper or not, may not be easily accessible," she says. "In other words, when examining public food choices, an unhealthy or even toxic environment needs to be considered and the outcome not just seen as a result of personal choices."

Watch the video below for how busy families can buy one key ingredient, like a chicken, and make five different meals for a week.