Salivary Alpha-Amylase Mediates the Increase in Hunger Levels in Adolescents with Excess Weight after Viewing Food Images

Background: Salivary alpha-amylase (sAA) initiates the digestion process in the mouth and its levels might influence feelings of hunger and the propensity toward obesity. This study aims to evaluate basal differences in sAA between adolescents with excess weight (EW) and normal weight (NW), and the associations between sAA levels and feelings of hunger after viewing food images. Methods: Adolescents (13-18 years old) classified as EW ( n  = 30) or NW ( n  = 30) participated in the study. Saliva samples were collected before the administration of a food-choice task. Hunger was evaluated before and after the food-choice task. Results: EW adolescents showed lower basal sAA levels than NW adolescents and a greater increase in hunger levels after viewing food images. In addition, sAA levels had a significant inverse relationship with the increase in hunger in EW adolescents, but not in NW adolescents. Finally, significant inverse associations between sAA, BMI, and body fat percentage were found. Conclusions: Levels of hunger and changes therein, after viewing food are dependent on sAA levels in EW adolescents. This finding indicates that sAA levels may be a mediator of feelings of hunger in individuals with overweight in the context of viewing food cues, suggesting the utility of the sAA enzyme as a marker of hunger and propensity toward obesity.