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Downsizing: policy options to reduce portion sizes to help tackle obesity

BMJ 2015; 351 doi: (Published 02 December 2015) Cite this as: BMJ 2015;351:h5863

Portion size matters
Click here to see an infographic, showing the impact of portion size, and how policies could be developed in response.

  1. Theresa M Marteau, professor of behaviour and health1,
  2. Gareth J Hollands, senior research associate 1,
  3. Ian Shemilt, senior research associate1,
  4. Susan A Jebb, professor of diet and population health2
  1. 1Behaviour and Health Research Unit, University of Cambridge, Cambridge, UK
  2. 2Nuffield Department of Primary Care Health Sciences, University of Oxford, UK
  1. Correspondence to: T M Marteau tm388{at}
  • Accepted 21 October 2015

Larger portions of food increase consumption. Theresa Marteau and colleagues suggest ways to reduce their size, availability, and appeal

The worldwide prevalence of obesity and overweight has risen substantially over the past three decades with no country yet achieving a reduction.1 International and national ambitions to “end childhood obesity”2 and “reduce non-communicable diseases by 25% by 2025”3 are unmatched by policies that could realise them. The causes of obesity are complex but overconsumption of food and sugary drinks is a critical proximal determinant, driven in part by large portion sizes. The importance of developing interventions and policies to reduce the size, availability, and appeal of large portions is underscored by the compelling evidence that people eat and drink more from larger portions.4

The problem

The size of portions, packages, and tableware has increased over the past 50 years (fig 1). Our recent Cochrane review shows that people consistently consume more food or non-alcoholic drinks when offered larger sized portions or packages, or when using larger items of tableware.4 The size of this effect suggests that eliminating larger portions from the diet could reduce average daily energy consumed by 12-16% among UK adults and by 22-29% among US adults. Our estimates are in line with those generated in another review on portion size using different methods.5

Fig 1 US and UK posters illustrating changes in portion, package, and tableware sizes since the 1950s. Reproduced with permission from Centers for Disease Prevention and Control and World Cancer Research Fund

Crucially, portion size is a modifiable determinant of dietary energy intake. Although clearer guidance on healthy portion sizes for a range of foods and drinks is awaited,6 most national and international policies to prevent obesity highlight a need to reduce portion sizes.7 8 Indeed, a recent …

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