Food preference and intake in response to ambient odours in overweight and normal-weight females.

In our food abundant environment, food cues play an important role in the regulation of energy intake. Odours can be considered as external cues that can signal energy content in the anticipatory phase of eating. This study aims to determine whether exposure to olfactory cues associated with energy dense foods leads to increased food intake and greater preference for energy-dense foods. In addition, we assessed whether BMI and hunger state modulated this effect. Twenty-five overweight (mean BMI: 31.3 kg/m(2), S.E.: 0.6) and 25 normal-weight (mean BMI: 21.9 kg/m(2), S.E.: 0.4) females, matched on age and restraint score, participated. In 6 separate sessions they were exposed to odours of three different categories (signalling non-food, high-energy food and low-energy food) in two motivational states (hungry and satiated). After 10 min of exposure food preference was assessed with a computerized two-item forced choice task and after 20 min a Bogus Taste Test was used to determine energy intake (kcal and g). In a hungry state, the participants ate more (p<.001) and preferred high-energy products significantly more often (p<.001) when compared to the satiated state. A trend finding for the interaction between hunger and BMI suggested that the food preference of overweight participants was less affected by their internal state (p=.068). Neither energy intake (kcal: p=.553; g: p=.683) nor food preference (p=.280) was influenced by ambient exposure to odours signalling different categories. Future studies need to explore whether food odours can indeed induce overeating. More insight is needed regarding the possible influence of context (e.g. short exposure duration, large variety of food) and personality traits (e.g. restraint, impulsive) on odour-induced overeating.