Impact of health warning labels on snack selection: An online experimental study

Natasha Clarke, Emily Pechey, Eleni Mantzari, Anna K.M. Blackwell, Katie De-loyde, Richard W. Morris, Marcus R. Munafò, Theresa M. Marteau, Gareth J. Hollands

Research output: Contribution to journalArticlepeer-review

17 Citations (SciVal)


Excessive consumption of energy-dense food increases the risk of obesity, which in turn increases the risk of non-communicable diseases, including heart disease, type 2 diabetes and most non-smoking-related cancers. Health warning labels (HWLs) that communicate the adverse health consequences of excess energy consumption could reduce intake of energy-dense foods. The aim of the current study was to estimate the impact on selection of energy-dense snacks of (a) image-and-text HWLs (b) text-only HWLs and (c) calorie information. In a between-subjects, 3 (HWL: image-and-text, text-only, no label) x 2 (calorie information: present, absent), factorial experimental design, participants (N = 4134) were randomised to view a selection of energy-dense and non-energy-dense snacks with one of five label types or no label. The primary outcome was the proportion of participants selecting an energy-dense snack in a hypothetical vending machine task. The proportion of participants selecting an energy-dense snack was reduced in all label groups, relative to the no label group (no label: 59%; calories only: 54%; text-only HWL: 48%; text-only HWL with calories: 44%; image-and-text HWL: 37%; image-and-text HWL with calories: 38%). Compared to the no label group, participants were least likely to select an energy-dense snack in the image-and-text HWL group (OR = 0.46, 95%CI = 0.40, 0.54, p < 0.001). Health warning labels – particularly those including an image and text - have the potential to reduce selection of energy-dense snacks in an online setting. Their impact on selection and consumption in real-world settings awaits testing.

Original languageEnglish
Article number104744
Publication statusPublished - 1 Nov 2020

Bibliographical note

Funding Information:
This work was funded by a Collaborative Award in Science from Wellcome Trust (Behaviour Change by Design: 206853/Z/17/Z to Theresa Marteau, Paul Fletcher, Gareth Hollands and Marcus Munafò).

Publisher Copyright:
© 2020 The Authors


  • Choice architecture
  • Energy-dense
  • Food
  • Graphic warnings
  • Health warning labels
  • Pictorial labels
  • Snacks

ASJC Scopus subject areas

  • Psychology(all)
  • Nutrition and Dietetics


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