In the late 1960s, Schachter and his colleagues developed a highly influential proposal that became known as the ‘externality theory of human obesity’. This theory argues that the obesity (and overeating) occurs because certain individuals are less sensitive to internal hunger and satiation cues, and are relatively more sensitive to external cues, including the sensory characteristics of food.

It has recently become clear that food-cue exposure (exposure to the sight or smell of food) can have a powerful effect on appetite. Even brief exposure to the sight and smell of food has been shown to increase reported appetite, initiate ‘cephalic phase responses’ (the release of insulin, changes in salivation, heart rate, gastric activity, and blood pressure), and increase planned and actual consumption.

Targeted clinical comparisons, such as those involving binge eaters and bulimics, show that individuals differ in their reactivity to food cues. Indeed, previous research from the NBU has demonstrated that overweight individuals might be especially sensitive to these established effects of food-cue exposure (Ferriday & Brunstrom, 2011). Specifically, in overweight individuals, exposure to the sight and smell of pizza (i) elicited a significantly greater salivary response and, (ii) evoked a significantly greater increase in desire to eat both the cued food and another non-cued food.

Current research in the NBU continues to address important questions in this area. For example, how do beliefs and expectations about food affect our response to a food cue?  Does experience with inconsistent (varied) flavour-nutrient pairings reduce cephalic phase responses to a food cue?

Relevant peer-reviewed publications:

• Hardman, CA, Rogers, PJ, Etchells, KA, Houstoun, KVE & Munafò, MR 2013, 'The effects of food-related attentional bias training on appetite and food intake' Appetite. Click here to read
• Ferriday, D & Brunstrom, JM 2011, 'I just can't help myself: effects of food-cue exposure in overweight and lean individuals' International Journal of Obesity, vol 35, pp. 142 - 149. Click here to read
• Ferriday, D & Brunstrom, JM 2008, 'How does food-cue exposure lead to larger meal sizes?' British Journal of Nutrition, vol 100, pp. 1325 - 1332. Click here to read