Portion sizes make it too easy to overeat, review finds

People really do eat more food and drink more non-alcoholic drinks when the portions are larger, say researchers who call for the size, availability and appeal of large servings to be reduced.

Our response to eat everything on larger plates may be more automatic than we realize

Growing portion sizes at restaurants, grocery stores, and at home are largely to blame for the growing obesity epidemic, U.K. researchers say 2:03

People really do eat more food and drink more non-alcoholic drinks when the portions are larger, say researchers who call for the size, availability and appeal of large servings to be reduced.

People consistently consumed more food and drink when offered larger-sized portions, packages or tableware than when offered smaller-sized versions, researchers said in the Cochrane Database of Systematic Reviews.

"At the moment, it's just all too easy and often a better value for money for us to eat and drink too much," said Ian Shemilt, a co-author of the review and a researcher in the behavioural health unit at the University of Cambridge.

Reducing the amount of food that ends up in front us in the first place is likely to be the key, he said. Overeating increases the risk of heart disease, Type 2 diabetes and many cancers.

The researchers estimated that if we were able to eliminate larger-sized portions completely, that could reduce energy intake by up to 279 calories a day among U.K. adults. Over the course of a week, that adds up to equivalent to what you might eat in a whole day.

Part of the challenge is that portion sizes have increased .  A portion size is the amount of food you actually put on your plate to eat in one sitting.  Some examples of "portion distortion":

  • About 20 years ago, a coffee shop muffin tended to be 2.5 ounces (71 grams) and 210 calories. Today, they can be 113 grams and up to 500 calories.
  • A plate of chicken Caesar salad two decades ago was about 1.5 cups big and had 390 calories.  Today's larger plates serve up about three cups of salad and nearly 800 calories.
  •  A portion of peanuts was 80 per cent larger in 2013 than in 1993, the British Heart Foundation says. 

Another challenge is we're often encouraged from an early age to eat everything on our plate.

But what the findings in the review suggest is that the environmental influences surrounding our food consumption, such as at home, at supermarkets, pubs and restaurants, could cause us to eat more sometimes without our awareness, Shemlit said.

"Responses to larger plates for example may be more automatic than conscious."

He suggested:

  • Place size limits on sugary drinks.
  • Cut portions of larger packages of energy-dense snacks such as those sold in vending machines.
  • Place larger portions in less accessible parts of the supermarket aisle, rather than at eye level.
  • Restrict price promotions that make larger servings or more servings per pack cost less in relative and sometimes absolute terms.

Consumers also need to do their part alongside governments and the food industry because both the supply and demand need to be reduced to recalibrate portion sizes to the amount of energy our bodies need, Shemilt said.

In Mexico, where nearly 33 per cent of the population is obese, one of former New York City mayor Michael Bloomberg's charities bought prime time ads to counter industry opposition to soda taxes to mobilize public demand for a soda tax, he said.

Nearly 62 per cent of Canadian men (8.2 million) and 46 per cent of women (6.1 million) were obese or overweight and faced increased health risks because of excess weight, based on the 2013 Canadian Community Health Survey.

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