In the first installment in our three-part Psychology of Food series, Andrea Janus asks the question: Are larger plates and portions to blame for our ballooning waistlines?

When a recent study showed that meals in paintings of the Last Supper had grown by biblical proportions over the last thousand years, it came as no surprise to experts who argue that ballooning portion sizes are a driving force behind the North American obesity epidemic.

The study, by renowned food and behaviour scientist Brian Wansink, found that the size of the main dish grew by 69 per cent and the size of the plate by 66 per cent in 52 paintings of Jesus' last meal completed between the years 1000 and 2000.

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While the findings, which were published in the International Journal of Obesity, pertain only to artists' renderings of portion sizes, they also mimic a real-life dramatic increase in the amount of food that we eat.

According to "Downsizing our consumption norms" a study by Wansink and Loert van Ittersum published in The Journal of the American Dietetic Association:

  • large-sized offerings in supermarkets have increased 10-fold since 1970.
  • "jumbo-sized" portions of foods are on average about 250 per cent larger than a normal portion.
  • the surface area of the average dinner plate has increased 36 per cent since 1960.

The study also found that the serving sizes of some entrees in popular cookbook "The Joy of Cooking" have increased by as much as 62 per cent since the tome was first published in 1920.

And all of these super-sized plates, packages and recipes mean we're ingesting super-sized portions of foods.

The same study found that people tend to serve themselves and consume between 20 and 40 per cent more from larger-sized packages, and eat between 30 and 50 per cent more from larger-sized restaurant portions.

We as consumers have not said no and stopped purchasing, which is our biggest chip in the game.

-- Heidi Bates, registered dietitian

 

Other studies by Wansink and his colleagues have even found that people don't believe they have eaten more when served with larger plates and portions, even when the evidence confirms they have.

The bottom line, according to Wansink and Van Ittersum, is that larger packaging and dishware and increased portion sizes have reduced our ability to regulate our food intake.

As a result, we eat more than we should.

"Large-sized packages, large-sized restaurant portions and large-sized dinnerware all have one thing in common," the authors wrote. "They all perceptually suggest to us that it is more appropriate, typical, reasonable and normal to serve and to eat more food than smaller plates or smaller packages would instead suggest."

At a time when studies show Canadians are less physically active than ever before, and therefore burning fewer calories, eating more has obvious ramifications: a 2008 Statistics Canada report found that more than 17 per cent of Canadian adults are obese.

In the United States, as many as 34 per cent of adults are obese, according to data released last year.

Restaurants don't profit from making people fat

But are the food manufacturing, dinnerware and restaurant industries solely to blame for how much food we're stuffing into our bodies? The short answer is no.

While fast-food restaurants compete for consumers' dollars by offering value-sized (i.e. super-sized) meals at cheap prices, Wansink points out that restaurants don't profit from making people fat. It's people who are ultimately responsible for what foods, and how much of them, go into their own mouths.

Registered dietitian Heidi Bates, of the University of Alberta's Department of Agricultural, Food and Nutritional Science in Edmonton, says the food industry is trying to "wow" consumers with large portions and cheap prices, but it's up to individuals to see through that.

"We certainly haven't said no to that, which is where our personal responsibility comes in," Bates told CTV.ca in a telephone interview. "Even in the face of the larger portion sizes, we as consumers have not said no and stopped purchasing, which is our biggest chip in the game."

But individuals aren't entirely to blame, according to Bates. She cites research that shows our ability to recognize larger portions as unhealthy has lagged behind the growth of the portions themselves.

"With food, if we are consistently exposed to large portion sizes and we don't have any other frame of reference, we blithely go along and you can't really change behaviour that you're not aware of," Bates said.

Indeed, how would the average person know that years ago, the average bagel equaled a 2-oz. serving, while today's bagels are about 4 oz. in size, or that the average muffin has tripled in size, from 50 g to 150 g? Or how would a restaurant-goer know that their fettuccine alfredo may be a whopping six times bigger than a normal serving size for pasta?

It's up to the individual

Despite that knowledge deficit, experts believe it comes down to consumer awareness and discipline to control how much we're eating.

The average man only needs between 2,500 and 3,000 calories and the average woman needs between 1,900 and 2,400 calories, depending on their physical activity levels.

But when a cheeseburger, an order of large French fries and a large Coke can add up to more than 1,100 calories, we can easily get half our daily calorie needs in just one meal.

The fast-food industry, despite being one of the leaders in the charge to oversized portions, has begun to adapt its menus to try and cater to customers who may be overhauling their lifestyles.

Individual portion-sized bags of chips, 100 calorie chocolate bars, the new 7.5-oz., 90-calorie cans of Coca Cola and McDonald's new McMini sandwiches, to name a few, are all designed for the health-conscious consumer.

But "are they something that can help teach people portion size, which they could be?" Bates wonders. "Or are they something that invites people to indulge and not think about it?"

Barbel Knauper, a McGill University psychology professor, believes that rather than create laws that require McDonald's to shrink portion sizes, individuals must take ownership of their own food choices.

Own what you eat

Knauper, alongside graduate student Ilana Kronick, conducts research into why people, especially dieters, form so-called compensatory intentions, such as a vow to skip dinner, in order to indulge in diet-busting foods. The problem is, research shows that most people don't follow through on the compensatory behaviour and therefore often fail to meet their weight-loss goals.

According to Knauper, people can be trained to become more aware of, and to resist, such behaviours, just as they can be trained to eat more appropriate portions no matter what packaging the food comes in.

"I'm a psychologist, so that's of course my mantra, to think we can empower people to better regulate and not fall prey to the environment," Knauper told CTV.ca in a telephone interview.

"Because otherwise we would all end up obese if we were not to a certain extent able to regulate our behaviour and not fall prey all the time to the portion sizes that are being offered to us."

Are you struggling to rein in the amount of food you eat? Read our story Paring Down Portions for more from registered dietitian Heidi Bates and Barbel Knauper on how you can once again own what you eat.