Background Obesity disproportionately affects socially disadvantaged groups. Differential exposure to advertising of high fat, salt and sugar (HFSS) foods and drinks has been proposed as one factor which may explain these social inequalities. This study explores sociodemographic differences in exposure to HFSS advertising and whether exposure is associated with body mass index.

Methods Adults recruited to the Kantar Fast Moving Consumer Goods panel for London and the North of England completed an online survey on their exposure to HFSS advertising in February 2019 (n=1552). We used logistic regression models to assess the association between self-reported exposure to HFSS advertising and sociodemographic characteristics: sex (male or female), age group (18–34 years, 35–44 years, 45–54 years, 55–64 years or ≥65 years), socioeconomic position (high, middle or low), children in the household (yes or no) and working status (full-time employee, part-time employee, self-employed, retired or not looking for work/unable to work). We further assessed associations stratified by product advertised (processed HFSS foods, sugary drinks, sugary cereals, sweet snacks, fast food or digital food delivery services) and advertising setting (traditional, digital, recreational, functional or transport). Lastly, we examined the association between self-reported advertising exposure and weight status.

Results Overall, 84.7% of participants reported exposure to HFSS advertising in the past 7 days. Participants in the middle (vs high) socioeconomic group had higher odds of overall self-reported exposure (OR 1.48; 95% CI 1.06–2.07). Participants in the low (vs high) socioeconomic group had higher odds of reporting exposure to advertising for four of six product categories (ORs ranging from 1.36 to 1.67), traditional advertising (OR 1.44; 95% CI 1.00–2.08) and digital advertising (OR 1.50; 95% CI 1.06–2.14). Younger adults (18–34 years vs ≥65 years) had higher odds of reporting exposure to digital food delivery service advertising (OR 2.08; 95% CI 1.20–3.59), digital advertising (OR 3.93; 95% CI 2.18–7.08) and advertising across transport networks (OR 1.96, 95% CI 1.11–3.48). Advertising exposure was associated with increased odds of obesity for digital food delivery services (OR 1.40; 95% CI 1.05–1.88), digital advertising (OR 1.80; 95% CI 1.33–2.44) and advertising in recreational environments (OR 1.46; 95% CI 1.02–2.09).

Conclusion Exposure to HFSS advertising was prevalent, with adults in lower socioeconomic groups and younger adults more likely to report exposure. Several types of HFSS advertising were associated with increased odds of obesity. Restricting HFSS food and drink advertising may help to reduce sociodemographic differences in obesity.