ReviewFrom lab to clinic: Extinction of cued cravings to reduce overeating
Introduction
Imagine a table full of your favorite sweet and savory temptations. Imagine the taste of these delicious foods. Imagine that you could eat them all without any restrictions. You will probably notice that your mouth is starting to water, and you might feel an intense desire to eat, even though you are unaware of many other physiological preparatory responses, such as insulin release, ghrelin response, stomach secretions, dopamine changes, activation of reward-associated areas in the brain and so on (see e.g., [21], [45], [65], [72], [88]). These appetitive responses to cues that signal the availability of food are collectively called food cue reactivity; the responding prepares the body for food intake and increases one's motivation to eat (e.g., [55]). Food cue reactivity during exposure to tasty foods is a normal and healthy response [22], [43], [54], [55]. However, compared to people without eating concerns, food cue reactivity is significantly stronger in concerned eaters, such as unsuccessful dieters, bulimia nervosa patients, binge eaters and obese people [22], [39], [41], [49], [56], [61], [73], [78], [87].
Increased food cue reactivity motivates eating, even in the absence of hunger and in excess of calories physically needed, and therefore easily results in overeating and weight gain [8], [10], [35], [42]. For example, overweight children demonstrated cued overeating while lean children did not and, in the overweight children, the amount eaten correlated strongly with increased salivary responding during exposure to the food (r = 0.62; [39]). Food cue reactivity not only contributes to the maintenance of overeating and weight gain – it also increases the risk of relapse during and after weight loss [42], [43]. Though there exist individual differences in food cue reactivity [14], [50], increased reactivity to food cues usually follows from Pavlovian appetitive conditioning, i.e., associative learning.
Section snippets
Acquisition of food cue reactivity
Food cue reactivity is easily learned. The early observations of Ivan Petrovich Pavlov are the most well-known: Pavlov observed digestive preparatory responses (e.g., salivation) in response to stimuli that signaled dog food, for example specific sounds or footsteps of the person feeding the dog (see [71]). During Pavlovian conditioning - or associative learning - the organism learns that a neutral stimulus predicts the occurrence of a second stimulus (e.g., the eating of dog food). The neutral
Extinction of food cue reactivity
Cued cravings might easily sabotage healthy eating. Dieting, losing weight and the maintenance of lost weight will also be more difficult with increasing levels of food cue reactivity. A reduction in reactivity to tempting food cues could eliminate the primary motivation for eating and might facilitate healthy eating, adherence to restrictive diets, weight loss and weight loss maintenance [42], [43], [44]. Indeed, obese individuals who have successfully lost weight salivated significantly less
Dieting and learning
Diets differ in many respects. For example, some diets are very strict and rigid, while others are more flexible. Some people just try to eat less of many food items during regular meals, others only drink shakes, and others skip meals, and so on. Although we do not know much about behavioral dieting strategies, people who lost weight successfully do report that they are continually strict dieters who show little variety in their diets [25], [64], [91].
In line with these findings, Van den Akker
Inhibition training
Extinction is inhibitory learning and not unlearning, suggesting that extinction might be related to one's ability to inhibit responding. Extinction procedures might therefore be more effective with stronger inhibition skills, while they might be less effective with weaker inhibition skills. One study in our lab indeed demonstrated that participants with weak inhibition skills show worse extinction of appetitive responses compared to participants with stronger inhibition skills ([76], [78]; but
Translation to the clinic: exposure therapy
The clinical analogue of extinction is exposure with response prevention, a well-known behavioral intervention during which participants are repeatedly exposed to unreinforced cues. Exposure therapy has been applied in anxiety disorders for many decades and appears to be effective in reducing fear and avoidance behavior. A translation to addictive disorders (e.g., [20]) and eating disorders (e.g., [34], [35], [36]) was made several decades ago. The food cue exposure with response prevention
Acknowledgements
This manuscript is based on work presented in a MARS lecture at the Annual Meeting of the Society for the Study of Ingestive Behavior in Denver, July 7–11, 2015.
This work is supported by the Netherlands Organisation for Scientific Research (NWO): Vici Grant 453.10.006, awarded to Anita Jansen.
We are grateful to Jessica M. Alleva for her help.
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