External Eating

External eating can be defined as eating in response to external food-related cues, such as the sight, smell and taste of food, regardless of physical need. External eating has been linked to overeating and it is considered a highly problemmatic eating behaviour due to its association with higher body weights, more unhealthy food intake and increased risk of relapse in eating disorders and obesity.  

External eating has been associated with increased BMI in a healthy weight sample. Furthermore, it is positively correlated with increased BMI in children and adults. External eating was found to be  extremely associated with fat intake than to carbohydrate intake. External eating  is positively correlated with laboratory based food intake in adolescent girls and candy consumption in children in experimental studies. It is  also associated  with unhealthy snack food intake in healthy weight women according to experimental studies . Results of the researchs also reported that external eating is linked to increased self-reported energy intake over three days and one month in healthy weight women. In a current study which has only women participants, external eating was associated with the intake of sweet food, rather than savoury food during the taste tests.

External eating behaviour was found to be associated with increased impulsivity especially in overweight and obese individuals. It was suggested that environmental cues affect eating behaviours of obese people more than non-obese people. However, more recent studies revealed that all weight classes can be influenced by environment.

External eating correspond to a relative insensitivity to internal hunger and satiety signals such as emotional eating. Externality theory focuses on the external environment such as food cues as a determinant of eating behaviour. Elevated responsiveness to food related cues in the immediate environment cause overeating of external eater. There is also a further difference of external eating from emotional eating. This difference has been considered as an evolutionary adaptive response that has been related to Neel’s thrifty-genotype concept. This concept suggests that evolution has favored genetic adaptations that allow humans to survive during periods of food shortages, including adaptations that allow them to overeat in times of food surplus (whenever external food cues are present in the environment) and rapidly develop fat on their bodies.

There are some interventions to struggle with external eating. Cognitive control training is one of them. This training strengths inhibitory control for reducing both attentional and motor impulsivity. It is found that using general inhibitory control training (i.e., repeatedly inhibiting responses to stimuli unrelated to food) reduced unhealthy food intake on a subsequent taste test. Others have used specific inhibitory control training that focuses on food stimuli and found that increased inhibitory control for chocolate cues as well as food in general  can reduce unhealthy food intake. In addition, increasing inhibitory control for unhealthy food resulted in weight loss among dieters with high BMI.

 

Another intervention is food-cue reactivity training. These intervention makes foods less tempting to external eaters by reducing the saliency of attractive food cues. This method was found effective at reducing cue reactivity  for unhealthy foods such as chocolate.  This particular intervention may be useful at reducing unhealthy food intake among individuals with problematic eating behaviour, specifically those with a pronounced external eating style.