A fondness for well-known fast-food and sugar-sweetened beverage brands may be a warning sign of poorer overall diet quality, even among people who recognise those brands as unhealthy, a new study suggests. Researchers say emotional attachment to food brands may influence eating habits in ways that nutritional knowledge alone cannot overcome.

Poor diet is a major contributor to obesity, type 2 diabetes, heart disease and some cancers, and can increase the risk of premature death. Researchers are increasingly examining whether the widespread marketing of fast food and sugary drinks contributes to diet-related chronic diseases by shaping consumers’ attitudes and choices.

“When people develop a psychological loyalty to fast-food brands, it acts as a strong predictor of their saturated fat and sugar intake – regardless of how healthy they perceive these brands to be,” said senior author Dr Poppy Watson from the University of Technology Sydney (UTS).

The research found that people who liked fast-food brands tended to consume more saturated fat and sugar. They were also more likely to perceive their preferred brands as healthier. According to the researchers, nutritional knowledge played a role in these perceptions, but how much participants liked a brand was an even stronger predictor of how healthy they believed it to be.

Published in the Journal of Health Communication, the research suggests that repeated exposure to branding may build familiarity and positive feelings that can spill over into perceptions of healthiness and dietary choices. The multidisciplinary research team included experts in medical science, psychology and marketing from UTS.

Researchers examined adults in Australia and the United States in two separate studies. Participants completed comprehensive dietary questionnaires and were asked about their attitudes towards fast-food and beverage brands, including how much they liked the brands and how healthy they believed them to be. The results revealed a consistent relationship between positive brand attitudes and poorer dietary patterns.

“Unhealthy food marketing is pervasive in retail, media, sport and other settings,” Watson said. She noted that companies invest heavily in marketing because it can influence purchasing decisions, even though consumers may not always recognise how strongly advertising and branding affect their choices. About one-third of calories consumed by adults in Australia and the US come from “discretionary” foods and drinks, including energy-dense products high in sugar, salt and saturated fat.

The findings suggest that improving nutritional knowledge may not be enough to encourage healthier eating if powerful brand attachments continue to shape perceptions and behaviour. Researchers argue that consumers should be more aware of how marketing can influence their health judgements. In contrast, governments and public health organisations may need to consider stronger restrictions on unhealthy-food advertising. Emotional attachment to a favourite fast-food brand, the study suggests, could influence what ends up on the plate despite nutrition warnings.

More information: Simone Rehn et al, Liking Fast-Food Brands Predicts Poorer Diet Quality, Independent of Perceived Healthiness, Journal of Health Communication. DOI: 10.1080/10810730.2026.2725159

Journal information: Journal of Health Communication Provided by University of Technology Sydney