NIHR Signal Larger portion, package or tableware size may increase food consumption

Published on 15 January 2016

This Cochrane review found that people ate and drank more when offered larger-sized portions or when using larger tableware (such as plates, bowls, bottles or glasses). However, the evidence for the effects of portion, package and tableware size on selection and consumption was of moderate quality and most of the included studies (58 of 72) were conducted in the US. The implications for commissioning and public health practice will require judgment and local knowledge.

The increase in consumption was about 215 to 279 kcal or 12 to 16% of the average energy intake for a UK adult. Adults increased their intake about twice as much as children. The findings re-enforce NICE guidance, which recommends encouraging people to limit their portion size.

The results also support public health programmes that try to reduce food or drink intake by including advice on portion size. No research on the portion size of alcoholic (as opposed to non-alcoholic) drink consumption was found.

Share your views on the research.

Why was this study needed?

Overeating, drinking too much alcohol and smoking have all been shown to increase the risk of cancers, heart disease, diabetes and various other non-communicable diseases. For example, an obese woman is 13 times more likely to develop type 2 diabetes. These diseases reduce quality of life and increase healthcare costs. Although the rate of smoking is gradually reducing in the UK, the rate of obesity is rising rapidly. The Health and Social Care Information Centre report that obesity rates have increased for men from 13.2% in 1993 to 26% in 2013 and from 16.4 to 23.8% for women.

People are repeatedly exposed to varying shapes and sizes of food, alcohol and tobacco products in shops, restaurants and bars. This review aimed to see how influential product size and shape is on our choices and consumption in order to inform health promotion interventions to reduce obesity, alcohol-related illness and smoking rates.

What did this study do?

This Cochrane systematic review and meta-analysis found 72 eligible randomised controlled trials. They compared at least two groups of people presented with a choice of size or shape of a portion, package or item of tableware, on their selection or consumption of food, alcohol or tobacco products. Sixty nine studies looked at food and non-alcoholic drinks and three at tobacco products; no studies on alcoholic drinks were found. Almost all of the studies assessed responses to different sizes rather than shapes.

The average age of participants ranged from three to 55 years, with more studies in adults than children.

The methods used for the review were sound and the researchers assessed the risk of eleven types of bias in the included studies. There was an unclear risk of bias in over 75% of studies reporting the consumption outcome and in 43 studies there were differences in the baseline characteristics between the comparison groups that themselves could have led to differences in outcome, independent of the intervention. Two of 72 included trials were from the UK whereas the majority were conducted in the USA, where portion sizes may be larger than in the UK. Therefore, these results need to be treated with some caution.

What did it find?

  • People consistently ate more food or drank more non-alcoholic drinks when offered larger-sized portions, packages or items of tableware than when offered smaller-sized versions. The effect was considered small to moderate, equivalent to about 215 to 279 kcal or 12 to 16% of average energy intake for a UK adult (Standardised Mean Difference [SMD] 0.38, 95% Confidence Interval [CI] 0.29 to 0.46). This came from a meta-analysis of 58 studies, 6603 participants.
  • The effect of portion size was greater (about double) amongst adults than children.
  • People selected more non-alcoholic drinks when they were offered them in shorter and wider glasses or bottles, compared to taller and narrower vessels. The effect was considered very large (SMD 1.47, 95% CI 0.52 to 2.43), but came from a meta-analysis of just three very diverse studies.
  • There was no difference when comparing longer and shorter cigarettes.

What does current guidance say on this issue?

NICE guidance, published in 2015, targeted at everyone who provides information on weight management, recommends encouraging people to choose smaller portions and avoid additional servings.

What are the implications?

At face value, the results suggest that policies and practices that reduce the size, availability and appeal of larger-sized portions, packages and tableware will reduce the amount people eat and drink. However better quality underlying research is required and despite the intuitively attractive conclusions, balanced policies in the complex area of obesity prevention will need more than one review. Potential interventions that could be tested further include education, changes to regulatory and legislative frameworks, voluntary agreements with the food industry, reducing default serving sizes of energy-dense food, or providing smaller crockery, cutlery and glasses in food outlets.

There was not enough evidence on whether the effect size varied between people from different socioeconomic groups, so it remains uncertain whether any successful interventions would reduce health inequalities. There was also not enough evidence to guide policy or practice on tobacco or alcohol “portion” or packet size.

Citation

Hollands GJ, Shemilt I, Marteau TM, et al. Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. Cochrane Database Syst Rev. 2015;9:CD011045.

Bibliography

C3 Collaborating for Health. Non-communicable diseases in the UK. A briefing paper prepared for the UK Parliament (House of Lords). London: C3 Collaborating for Health; 2011.

Health and Social Care Information Centre. Statistics on Obesity, Physical Activity and Diet. England 2015. Leeds: Health and Social Care Information Centre; 2015.

Health and Social Care Information Centre. Statistics on Smoking. England 2015. Leeds: Health and Social Care Information Centre; 2015.

NICE. Maintaining a healthy weight and preventing excess weight gain among adults and children. NG7. London: National Institute for Health and Care Excellence; 2015.

Marteau TM, Hollands GJ, Shemilt I, et al. Downsizing: policy options to reduce portion sizes to help tackle obesity. BMJ. 2015; 351: h5863.

Why was this study needed?

Overeating, drinking too much alcohol and smoking have all been shown to increase the risk of cancers, heart disease, diabetes and various other non-communicable diseases. For example, an obese woman is 13 times more likely to develop type 2 diabetes. These diseases reduce quality of life and increase healthcare costs. Although the rate of smoking is gradually reducing in the UK, the rate of obesity is rising rapidly. The Health and Social Care Information Centre report that obesity rates have increased for men from 13.2% in 1993 to 26% in 2013 and from 16.4 to 23.8% for women.

People are repeatedly exposed to varying shapes and sizes of food, alcohol and tobacco products in shops, restaurants and bars. This review aimed to see how influential product size and shape is on our choices and consumption in order to inform health promotion interventions to reduce obesity, alcohol-related illness and smoking rates.

What did this study do?

This Cochrane systematic review and meta-analysis found 72 eligible randomised controlled trials. They compared at least two groups of people presented with a choice of size or shape of a portion, package or item of tableware, on their selection or consumption of food, alcohol or tobacco products. Sixty nine studies looked at food and non-alcoholic drinks and three at tobacco products; no studies on alcoholic drinks were found. Almost all of the studies assessed responses to different sizes rather than shapes.

The average age of participants ranged from three to 55 years, with more studies in adults than children.

The methods used for the review were sound and the researchers assessed the risk of eleven types of bias in the included studies. There was an unclear risk of bias in over 75% of studies reporting the consumption outcome and in 43 studies there were differences in the baseline characteristics between the comparison groups that themselves could have led to differences in outcome, independent of the intervention. Two of 72 included trials were from the UK whereas the majority were conducted in the USA, where portion sizes may be larger than in the UK. Therefore, these results need to be treated with some caution.

What did it find?

  • People consistently ate more food or drank more non-alcoholic drinks when offered larger-sized portions, packages or items of tableware than when offered smaller-sized versions. The effect was considered small to moderate, equivalent to about 215 to 279 kcal or 12 to 16% of average energy intake for a UK adult (Standardised Mean Difference [SMD] 0.38, 95% Confidence Interval [CI] 0.29 to 0.46). This came from a meta-analysis of 58 studies, 6603 participants.
  • The effect of portion size was greater (about double) amongst adults than children.
  • People selected more non-alcoholic drinks when they were offered them in shorter and wider glasses or bottles, compared to taller and narrower vessels. The effect was considered very large (SMD 1.47, 95% CI 0.52 to 2.43), but came from a meta-analysis of just three very diverse studies.
  • There was no difference when comparing longer and shorter cigarettes.

What does current guidance say on this issue?

NICE guidance, published in 2015, targeted at everyone who provides information on weight management, recommends encouraging people to choose smaller portions and avoid additional servings.

What are the implications?

At face value, the results suggest that policies and practices that reduce the size, availability and appeal of larger-sized portions, packages and tableware will reduce the amount people eat and drink. However better quality underlying research is required and despite the intuitively attractive conclusions, balanced policies in the complex area of obesity prevention will need more than one review. Potential interventions that could be tested further include education, changes to regulatory and legislative frameworks, voluntary agreements with the food industry, reducing default serving sizes of energy-dense food, or providing smaller crockery, cutlery and glasses in food outlets.

There was not enough evidence on whether the effect size varied between people from different socioeconomic groups, so it remains uncertain whether any successful interventions would reduce health inequalities. There was also not enough evidence to guide policy or practice on tobacco or alcohol “portion” or packet size.

Citation

Hollands GJ, Shemilt I, Marteau TM, et al. Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. Cochrane Database Syst Rev. 2015;9:CD011045.

Bibliography

C3 Collaborating for Health. Non-communicable diseases in the UK. A briefing paper prepared for the UK Parliament (House of Lords). London: C3 Collaborating for Health; 2011.

Health and Social Care Information Centre. Statistics on Obesity, Physical Activity and Diet. England 2015. Leeds: Health and Social Care Information Centre; 2015.

Health and Social Care Information Centre. Statistics on Smoking. England 2015. Leeds: Health and Social Care Information Centre; 2015.

NICE. Maintaining a healthy weight and preventing excess weight gain among adults and children. NG7. London: National Institute for Health and Care Excellence; 2015.

Marteau TM, Hollands GJ, Shemilt I, et al. Downsizing: policy options to reduce portion sizes to help tackle obesity. BMJ. 2015; 351: h5863.

Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco

Published on 15 September 2015

Hollands, G. J.,Shemilt, I.,Marteau, T. M.,Jebb, S. A.,Lewis, H. B.,Wei, Y.,Higgins, J. P.,Ogilvie, D.

Cochrane Database Syst Rev Volume 9 , 2015

BACKGROUND: Overeating and harmful alcohol and tobacco use have been linked to the aetiology of various non-communicable diseases, which are among the leading global causes of morbidity and premature mortality. As people are repeatedly exposed to varying sizes and shapes of food, alcohol and tobacco products in environments such as shops, restaurants, bars and homes, this has stimulated public health policy interest in product size and shape as potential targets for intervention. OBJECTIVES: 1) To assess the effects of interventions involving exposure to different sizes or sets of physical dimensions of a portion, package, individual unit or item of tableware on unregulated selection or consumption of food, alcohol or tobacco products in adults and children.2) To assess the extent to which these effects may be modified by study, intervention and participant characteristics. SEARCH METHODS: We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, eight other published or grey literature databases, trial registries and key websites up to November 2012, followed by citation searches and contacts with study authors. This original search identified eligible studies published up to July 2013, which are fully incorporated into the review. We conducted an updated search up to 30 January 2015 but further eligible studies are not yet fully incorporated due to their minimal potential to change the conclusions. SELECTION CRITERIA: Randomised controlled trials with between-subjects (parallel-group) or within-subjects (cross-over) designs, conducted in laboratory or field settings, in adults or children. Eligible studies compared at least two groups of participants, each exposed to a different size or shape of a portion of a food (including non-alcoholic beverages), alcohol or tobacco product, its package or individual unit size, or of an item of tableware used to consume it, and included a measure of unregulated selection or consumption of food, alcohol or tobacco. DATA COLLECTION AND ANALYSIS: We applied standard Cochrane methods to select eligible studies for inclusion and to collect data and assess risk of bias. We calculated study-level effect sizes as standardised mean differences (SMDs) between comparison groups, measured as quantities selected or consumed. We combined these results using random-effects meta-analysis models to estimate summary effect sizes (SMDs with 95% confidence intervals (CIs)) for each outcome for size and shape comparisons. We rated the overall quality of evidence using the GRADE system. Finally, we used meta-regression analysis to investigate statistical associations between summary effect sizes and variant study, intervention or participant characteristics. MAIN RESULTS: The current version of this review includes 72 studies, published between 1978 and July 2013, assessed as being at overall unclear or high risk of bias with respect to selection and consumption outcomes. Ninety-six per cent of included studies (69/72) manipulated food products and 4% (3/72) manipulated cigarettes. No included studies manipulated alcohol products. Forty-nine per cent (35/72) manipulated portion size, 14% (10/72) package size and 21% (15/72) tableware size or shape. More studies investigated effects among adults (76% (55/72)) than children and all studies were conducted in high-income countries - predominantly in the USA (81% (58/72)). Sources of funding were reported for the majority of studies, with no evidence of funding by agencies with possible commercial interests in their results.A meta-analysis of 86 independent comparisons from 58 studies (6603 participants) found a small to moderate effect of portion, package, individual unit or tableware size on consumption of food (SMD 0.38, 95% CI 0.29 to 0.46), providing moderate quality evidence that exposure to larger sizes increased quantities of food consumed among children (SMD 0.21, 95% CI 0.10 to 0.31) and adults (SMD 0.46, 95% CI 0.40 to 0.52). The size of this effect suggests that, if sustained reductions in exposure to larger-sized food portions, packages and tableware could be achieved across the whole diet, this could reduce average daily energy consumed from food by between 144 and 228 kcal (8.5% to 13.5% from a baseline of 1689 kcal) among UK children and adults. A meta-analysis of six independent comparisons from three studies (108 participants) found low quality evidence for no difference in the effect of cigarette length on consumption (SMD 0.25, 95% CI -0.14 to 0.65).One included study (50 participants) estimated a large effect on consumption of exposure to differently shaped tableware (SMD 1.17, 95% CI 0.57 to 1.78), rated as very low quality evidence that exposure to shorter, wider bottles (versus taller, narrower bottles) increased quantities of water consumed by young adult participants.A meta-analysis of 13 independent comparisons from 10 studies (1164 participants) found a small to moderate effect of portion or tableware size on selection of food (SMD 0.42, 95% CI 0.24 to 0.59), rated as moderate quality evidence that exposure to larger sizes increased the quantities of food people selected for subsequent consumption. This effect was present among adults (SMD 0.55, 95% CI 0.35 to 0.75) but not children (SMD 0.14, 95% CI -0.06 to 0.34).In addition, a meta-analysis of three independent comparisons from three studies (232 participants) found a very large effect of exposure to differently shaped tableware on selection of non-alcoholic beverages (SMD 1.47, 95% CI 0.52 to 2.43), rated as low quality evidence that exposure to shorter, wider (versus taller, narrower) glasses or bottles increased the quantities selected for subsequent consumption among adults (SMD 2.31, 95% CI 1.79 to 2.83) and children (SMD 1.03, 95% CI 0.41 to 1.65). AUTHORS' CONCLUSIONS: This review found that people consistently consume more food and drink when offered larger-sized portions, packages or tableware than when offered smaller-sized versions. This suggests that policies and practices that successfully reduce the size, availability and appeal of larger-sized portions, packages, individual units and tableware can contribute to meaningful reductions in the quantities of food (including non-alcoholic beverages) people select and consume in the immediate and short term. However, it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range. We are unable to highlight clear implications for tobacco or alcohol policy due to identified gaps in the current evidence base.

The size of a portion or package is a modifiable property of food, alcohol and tobacco products that may influence their selection and consumption. The size of an item of tableware used to consume such products may similarly influence their selection and consumption. Examples include the size of a pasta dish served to restaurant customers, the size or shape of plates or glasses that these products are served on and in, and the number of cigarettes in packets sold in shops or the length of each cigarette. The intervention in this review involved manipulation of the size or physical dimensions of a food, alcohol or tobacco product, its packaging or the tableware used in its consumption. The comparisons of interest were between products, packages or items of tableware that differ in terms of these properties.

Expert commentary

This well conducted review identifies that reduced portion sizes can make a material difference to energy consumption, and thus to obesity. While this might appear merely to confirm the glaringly obvious, it is a valuable finding: not only is the apparently obvious sometimes not true, there is a growing demand for evidence to support public health interventions (whether or not there is evidence to support the status quo). This review thus contributes useful information on a piece of the jigsaw puzzle of an effective response to obesity. Smaller portions aren't going to solve the problem on their own, but they can certainly help.

The main challenge, of course, lies in turning this knowledge into action. The review did not address the effectiveness of intervention strategies, but there are clear implications for the ways in which food is served and sold. Whether changes to portion sizes of foods, drinks and snacks will take place without government intervention remains to be seen, and whatever changes are implemented it will be important to identify and respond to any unintended consequences.

Dr Harry Rutter, Senior Clinical Research Fellow, London School of Hygiene and Tropical Medicine

Expert commentary

There are some troubling flaws with this review. To start with, the combining of food, tobacco and alcohol into one review is odd. The research on tobacco is limited and dated and there are no results for alcohol whatsoever – this is really a review only about food. The evidence is at best ‘moderate’, often ‘low’ or ‘very low’, yet the conclusions are repeatedly exaggerated in the text, and the stated implication that reducing plate sizes could solve the obesity crisis is pure conjecture. My concern is that the evidence in the full report has been misleadingly contracted into the executive summary, which in turn will be précised into a press release, and then further distilled into a tabloid newspaper report which will promote the putative benefits of reducing portion size, without a full assessment of the very flimsy evidence which was used to reach these conclusions. I accept the concept that increased portion size is bad, and that it is likely to be a driver behind the obesity epidemic, but without adequate scientific evidence, a scientific review is untenable.

Professor David Haslam, GP and Physician in Obesity Management, Luton & Dunstable Hospital, and Chair of the National Obesity Forum

Categories