Stress, Genetics, or Words? What Drives People to Eat Excessively?
New results from a pair of studies suggest that lean individuals and those with obesity experience different brain responses to written food words, and that both stress and genetics could influence excess eating. The findings will be presented at The Obesity Society Annual Meeting at ObesityWeek 2015.
"Food cues" can be internal or external environmental factors that influence the desire to eat, like emotions, images, smells, tastes, including food words. Food words may be considered a minimal food cue but they could significantly influence eating behavior with their presence in advertising contexts.
In one study, 17 individuals with obesity and 12 of normal weight underwent a functional magnetic resonance imaging (fMRI) scan while seeing words that described high-calorie foods, low-calorie foods, and non-foods. They then rated how much they wanted to eat each food item.
Researchers found that after experiencing stress, obese individuals were more likely to consume energy-dense foods compared to those of normal weight. Obese individuals exhibited heightened neural responses to minimal food vs. non-food word cues as well as high energy-dense vs. low energy-dense food word cues under non-stressed conditions. Under stress, both obese and lean adults showed some increased neural food cue responses but only the obese individuals consumed more at a subsequent meal.
In the second study, 35 adolescents between 14–19 years old with varying familial risk for obesity were genotyped. A computer paradigm was used to assess subjective appetite responses to food and non-food words, and food consumption was measured in a lab meal that followed. A questionnaire measuring habitual self-regulation of intake was also completed by the study participants.
Researchers saw an association between higher genetic obesity risk in teenagers based on several known obesity-associated genetic variants and subjective responses to food words. MC4R, a specific genetic variant, was tied to a greater intake of high-calorie foods during the lab test meal, while FTO, another variant, was associated with lower scores on a questionnaire measuring self-regulation of food intake.
Susan Carnell PhD, from Johns Hopkins University School of Medicine, and leader of both studies, highlighted the need to better understand how the external food environment interacts with biology. Study findings may help patients with obesity or those at risk through the development of behavioral interventions and help clinicians identify behavioral treatment strategies based on reducing the impact of food cues, especially for those at high risk for obesity.
“Our study found that individuals with obesity had a stronger response to words associated with high-calorie foods - such as chocolate spread and chicken wings - in a widespread neural circuit spanning multiple areas of the brain,” said Dr. Carnell. “When we subjected individuals to a combined social and physiological stressor, both individuals with obesity and those of normal weight showed slightly altered responses to high-calorie food words, but only those with obesity ate more at a subsequent meal. This suggests that people with obesity show a consistently different response to mere words describing foods than lean individuals. This could contribute to excess intake of energy-dense foods in both stressful and non-stressful environments.”For more information visit Obesity.org.