Exploring the Sensations of Taste in Anorexia and Bulimia Nervosa: A Plan for a Quasi-Experimental, Cross-Sectional Study to Understand Whether Food Preferences Shift Toward Dislike or Enhanced Enjoyment in Eating Disorders
A new study aims to shed light on the relationship between taste perception, hedonic valence (pleasure derived from taste), and eating disorders, particularly anorexia nervosa (AN) and bulimia nervosa (BN). The research, which has been approved by the Swiss ethics committee (CER-VD, n° 2016-02150) and the Ethics Review Panel of the University of Luxembourg, explores how altered sensory and affective responses to food influence food avoidance and binge-eating episodes.
Taste Perception and Hedonic Valence in AN and BN
Individuals with AN often show decreased somatosensory-gustatory responsiveness in brain regions such as the inferior parietal lobe, which processes sensory input from the tongue, lips, and teeth. This diminished taste and sensory processing correlates with food being rated as less pleasant, facilitating restrictive eating and fasting behaviors characteristic of AN.
In BN, while direct evidence from the study is limited, the disorder’s hallmark binge-eating episodes may be linked to impaired regulation of hedonic drives and reward mechanisms, making highly palatable foods more compelling despite attempts at control.
Food Avoidance
In AN, food avoidance is reinforced by both physiological and psychological factors: decreased pleasantness of food and heightened anxiety about eating. This leads to restriction and low body weight. Avoidant/restrictive food intake disorder (ARFID), related but distinct from AN, involves food avoidance driven by sensory sensitivity (e.g., tastes, textures) or anxiety about eating, not body image fears.
Binge-Eating Episodes
BN involves cycles of binge eating often followed by compensatory behaviors (vomiting, laxative use) and is characterized by a loss of control over eating. Physical and gastrointestinal symptoms such as delayed fullness, nausea, heartburn, and constipation linked to disordered eating can contribute to distress around meals and may perpetuate binge behaviors as a maladaptive coping strategy.
The dysregulation of normal hunger and fullness cues in ED recovery highlights the complex interaction between physiological signals and hedonic responses influencing binge episodes.
The Study
The study will be conducted in two parts:
- Study 1 will present four mixtures of sweet-fat stimuli in a sensory two-alternative forced-choice test. The responses of currently-ill AN and BN patients will be compared to those who have recovered from AN and BN, as well as to those of healthy normal-weight and underweight individuals without any eating disorder pathology.
- Study 2 will carry out a full-scale taste reactivity test, including psychophysiological and behavioral measures. The role of cognitions influencing these mechanisms will be examined in the study.
If taste response profiles are differentially linked to ED types, future studies may investigate taste responsiveness as a useful diagnostic measure in the prevention, assessment, and treatment of eating disorders. The study will not require trial registration.
- The study, focused on health-and-wellness and mental-health, aims to utilize eye tracking during Study 1 to examine differences in taste perception between individuals with eating disorders, such as AN and BN, and healthy individuals, potentially paving the way for using taste responsiveness as a diagnostic tool for eating disorders.
- In addition to eye tracking, Study 2 of the research will delve into the realm of science, employing a full-scale taste reactivity test to investigate the impact of cognitions on hedonic valence and behavioral responses in individuals with eating disorders, offering insights into the complex interaction between taste, mental health, and health-and-wellness.
