Obesity and Olfaction

Obesity is a complex condition that increases a range of health risks including up to 13 different cancers (WHO, 2022). In Europe, around 60% of adults are either overweight or obese and, worryingly, it is expected that none of the countries in the region will meet the goal of stopping the rise by 2025 (WHO, 2022). In addition to the health risks, there is a substantial burden to a nation’s health care resources. Just one example of the latter is illustrated in the UK, where obesity costs are estimated to be £6 billion per year, which is estimated to be more than the combined budgets of the police, fire service and judicial system (PHE, 2017). Whilst the basic cause of being overweight and obese is well characterised by a positive energy balance, the reasons why some individuals are more predisposed are complex and involve a number of factors, including genes, environment, social deprivation, diet and lifestyle (Bouchard, 2021, WHO, 2022). One aspect that has gained more recent attention is the possible role of our senses of smell and taste in obesity, in particular, whether there are differences in the ability to smell between obese and non-obese individuals and the extent to which these link to weight gain. This area has seen intense activity in recent years, with many separate lines of research which can be overlooked; this chapter aims to set out the main methodological framework for studying this area and review the relevant research.