Can reduced portions reduce consumption? IGD reviews the evidence

Could size reductions lead to reduced energy intake?
Could size reductions lead to reduced energy intake?

Related tags Portion size Food Nutrition

Many food companies are promoting smaller portions and reducing the size of existing products as part of a plan to reduce overall calorie intake – but is this the most effective approach?

In this guest article, IGD’s nutrition and scientific affairs executive Hannah Arnold examines the current evidence around portion sizes and consumption, and calls for more research into the best ways to help people manage their energy intake.

Portion size: The need for more research

People are leading increasingly busy lives and when it comes to eating more healthily many are looking to the food industry to help. Eight out of ten shoppers (79%) tell us they believe the industry has a role in tackling obesity and only 7% believe it has no role.

Many food and drink companies are exploring ways to make every day products healthier. Several have signed up to the UK Government’s Public Health Responsibility Deal, with 20 companies currently committed to help reduce the population’s calorie intake by five billion a day.

This calorie reduction pledge includes several options such as reducing the size of existing products or menu items and promoting smaller sizes.

Despite increasing evidence that the provision of larger portion sizes can lead to increased consumption, there is currently no conclusive evidence to demonstrate that specific size reductions will lead to a decrease in overall energy intake.

IGD’s working group pinpoints knowledge gap

IGD is a charity and our industry groups bring experts together to work on industry-wide challenges for everyone’s benefit.

Our industry nutrition strategy group (INSG) brings together nutritionists, scientists & regulatory personnel from food companies, trade associations and NGOs.

This year an INSG working group reviewed the current evidence for portion size of pre-packaged food and drink and consumption behaviour. This included determining informal aspects that can influence portion size through interviews with retailers, manufacturers and food service companies.  

Information was also collected from a stakeholder workshop to identify gaps in the current evidence base, and exploring all relevant literature in relation to pre-packaged foods and consumption behaviour.

The existing literature is sparse and only a few conclusions can be drawn. The studies reported are often short-term, conducted in controlled settings and do not provide evidence for longer-term outcomes or free living behaviours.

Recommendations for research priorities

IGD’s INSG portion size working group reviewed the information collected and made some clear recommendations for priority areas of research that may help to identify ways to help consumers manage energy intake from pre-packaged products:

  1. 1.       Determine whether portion size of pre-packaged products is the optimum mechanism to help consumers manage intake

From current evidence it’s not clear if portion size reduction is actually the most appropriate approach to help consumers manage their energy intake. Research should explore a range of mechanisms including physical indicators of portion size, text-based and pictorial messages. The impact of all these various methods on both the quantity of product consumed and the impact on overall daily intake should be assessed.

  1. 2.       Promotional dynamics: How shoppers use foods purchased from promotions

Promotions are commonplace in supermarkets and a range of different promotions is used across food and drink categories. These may encourage different behaviours by shoppers, including increasing the quantity of product purchased on a single occasion and in turn increasing the amount consumed over time. Research is needed to understand how different promotional mechanics across various categories and portion sizes can impact purchasing and in turn consumption behaviour. 

Next steps

The food industry recognises its responsibility to help people make healthier choices. However portion size is a complex area and untangling the many variables, such as product category, eating environment and consumer profile, to produce a coherent strategy is a considerable challenge.

To achieve effective change and avoid any unintended consequences more research needs to be done so that evidence-based decisions can be made.

For more information on IGD’s findings, please read our free factsheet at

Arnold_Hannah_ 1
Hannah Arnold, IGD

Related topics Market Trends Views

Related news

Show more

1 comment

This report ignores a large body of research

Posted by Pierre Chandon,

Interesting report but it doesn't take into account the findings from behavioral research showing how portion sizes influence eating. Read a recent review paper here:

Report abuse

Follow us


View more