In 2014, McKinsey published a report which assessed the efficacy of a variety of levers commonly used to try and tackle obesity. This included parental education, labelling, price promotions, surgery, media restrictions and portion size. The study found that portion size is the most impactful intervention when it comes to tackling obesity, and is also one of the most cost effective (“Overcoming obesity: An initial economic analysis”, November 2014).
This is also recognised by the public, with 60% of consumers agreeing that small portion sizes help them manage their calorie intake( Toluna, 2020).
The UK Government has also recognised the importance of portion size. The Public Health England sugar reduction programme (2016-2020) identified three routes to help consumers reduce their sugar and calorie consumption: offering small portion sizes; along with reformulation of existing products and the development of new products.
In the case of chocolate confectionery, smaller portion sizes were in fact the preferred mechanism. This is because simply removing sugar is not straightforward – it plays a pivotal role in chocolate confectionery, creating bulk, texture, and colour as well as sweetness. Substitutes for sugar need to be suitable in functionality, be ‘acceptable’ to consumers and meet regulatory approval. Replacements for sugar can be higher in calories, include side effects, and the taste may not be preferred.
Helping consumers limit or reduce their intake of calories and sugar by offering smaller portions avoids all of these issues.
However, the new restrictions on marketing HFSS foods in the Health and Care Act 2022 make no reference to portion size. The definition of the foods in scope are based on broad food categories, subject to the application of the Ofcom Nutrient Profile Model. Neither the categories nor the NPM take portion size into account.
 McKinsey Report (“Overcoming obesity: An initial economic analysis”, November 2014),
 Toluna 2020
References to scientific studies here.