Chemosensory Aspects in Obesity: Rethinking the Role of Sweet and Fat Taste

Liking for the sweetness of sugars and consumption of high fat-sugar diets are hot topics in the study of human ingestive behaviour, where controlling excess sugar and saturated fat intake is the focus of dietary guidelines and public health nutrition policies to tackle obesity globally. Contrary to the simple view that sweet liking is universal, in the first section of this chapter we review half a decade of empirical evidence for clear interpersonal variations in hedonic responses to sweetness with a three-phenotype model prevailing: a rise in liking with increasing sweetness (extreme sweet likers), liking for moderate but not intense sweetness (moderate sweet likers), and a decline in liking as sweetness increases (sweet dislikers). We then summarise how these phenotypic differences relate to diet and anthropometry and discuss the potential link between a strong liking for sweetness and enhanced responsiveness to internal cues considering alliesthesia and contemporary theories of interoception. In the second section we re-examine fat taste, distinguishing between oral detection of specific free fatty acids (FFAs) (i.e., fat “taste”) and hedonic evaluations of complex fat-based stimuli (i.e., fat “flavour”) and discuss how they might relate to body size and obesity. Finally, we review how fat perception may change with both accumulation and loss of fat from the body. Overall, we question the claims that sweetness elicits universal liking responses, with particular emphasis on disentangling the conventional wisdom that a strong liking for sweetness drives overconsumption, ultimately leading to weight gain and obesity. Instead, we propose that liking for fat may be a better predictor and propose future perspectives that take into account wider interpersonal characteristics.