Reducing the size of large food portions, packaging and tableware could help to tackle obesity, according to a report published in the BMJ.

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Large portions can lead to obesity and overweight.

Obesity has risen globally over the past 30 years, with no country yet achieving a reduction. Countries set goals of ending childhood obesity but lack policies that could make it happen.

The causes of obesity are complex, but overconsumption of food and sugary drinks is a key factor, driven in part by large portion sizes.

A recent Cochrane review by Theresa Marteau, from the University of Cambridge in the UK, and colleagues provides the "most conclusive evidence to date" that people consume more food or drinks when faced with larger size portions or packages, and when using larger items of tableware.

The researchers show that eliminating larger portions completely could reduce daily energy intake consumed by 22-29% among US adults.

Possible ways to reduce portion size

On this basis, the team put forward potential policy changes that could reduce the size, availability and appeal of large food and drink portions, to help reduce excessive consumption and prevent obesity.

The suggestions include:

  • Reducing serving sizes of high-calorie food and drink, such as the standard single serving of candies, fries and cakes
  • Reducing availability of larger portion and package sizes, for example, by removing the largest serving size
  • Making larger portion sizes in stores and cafes less accessible, for example, by limiting portion size at checkouts, aisle ends and special displays
  • Restricting pricing practices that enable larger portion and package sizes to cost less in relative terms than smaller sizes, and restricting price promotions on larger portion and package sizes
  • Highlighting single portion sizes in packaging
  • Restricting portion and package sizes in advertisements 
  • Making smaller tableware the norm for self-service and served foods and drinks, including plates, cups and glasses
  • Designing tableware to encourage smaller mouthfuls, such as shallow plates, straight-sided glasses and smaller cutlery
  • Pricing tableware in relation to size.

The authors note that sizes of portions, packages and tableware have grown over the past 50 years, and they suggest that 1950s-type portion and tableware sizes could be the optimum size. For food and drinks that are high in energy, the size may have to be reduced by over 50%.

Dealing with resistance

The changes may be unpopular, but as portion size is a modifiable determinant of energy intake, they could make a difference. The researchers refer to a recent economic analysis that cites portion size reduction as the most likely factor to reduce the population health burden of obesity.

Since the food industry could find it hard to make the first move, a combination of regulatory and non-regulatory measures to help set up a "virtuous circle" that could lead to recalibrated portions may be in order.

Regulations would be easier to enforce in public sector organizations, such as schools, hospitals, military bases and prisons than in industry, so agreements could be voluntary but reinforced by "disincentives or sanctions for nonparticipation."

The authors comment:

"Although policy makers and the food industry have primary responsibility for action, public acceptability is likely to be an important facilitator."

Tobacco controls are a good example of how potentially difficult health initiatives have mobilized public support.

Some studies have already indicated that people would be willing to accept smaller portion sizes. In a US campus restaurant, 14-33% of those invited to halve the size of a starchy side dish accepted, whether or not there was a discount.

Uncertainties include not knowing how far portion sizes can be reduced before becoming unacceptably small, and whether people would actually eat less, or if they would be tempted to have two plates instead of one.

Medical News Today recently reported that being overweight or obese when young can increase the chance of sudden cardiac death.