Cambridge scientists have shown that the reward centres of some peoples' brains are more sensitive to appetising food cues, and may help explain compulsive eating disorders.
And a leading obesity expert told FoodNavigator.com that the research appears to oppose claims that food advertising does not affect consumption, only brand choice.
"The fact that our study used pictures of food has additional pertinence to understanding the current high prevalence of these [compulsive-eating] disorders, because such images are widely used in modern society to promote food selection and intake (eg., advertising, product packaging, vending machines," wrote lead author John Beaver at the Medical Research Council Cognition and Brain Sciences Unit.
The scientists showed the 14 right-handed, healthy volunteers a series of pictures of foods classified as highly appetising like chocolate cake and ice cream sundaes, bland like uncooked rice and potatoes, disgusting like rotten meat and mouldy brean, and non-food objects like a videocassette or an iron.
The new study, published in the Journal of Neuroscience (Vol. 26, pp. 5160-5166), used functional magnetic resonance imaging (fMRI) to measure brain activity in regions of the brain previously linked to responding to food cues ventral striatum, amygdala, orbitofrontal cortex, ventral pallidum and the midbrain regions.
"As predicted, we found that individual differences in trait reward drive [the tendency to pursue the reward] were strongly correlated with activation to pictures of appetising foods in a neural network," wrote Beaver.
The volunteers were asked to rate the degree of stimulation to each food stimulus on a scale of one to seven, which indicated the extent the image was disgusting, pleasant, or arousing.
The average disgusting rating for appetising food was 1.26, compared to disgusting food, which had a disgusting rating of 4.38. Conversely, the pleasant rating for appetising food was 4.75, while disgusting food had a pleasant rating of 1.46.
Interestingly, the arousing ratings of both disgusting and appetising food were similar, 4.56 versus 4.21.
This result is not so surprising, said the researchers, since the measurement is related a persons ability to pursue and cope with appetising or disgusting stimuli.
"Our study is the first to bridge the gap between these [behavioural and neurobiological] important areas of research, providing insight into the neural mechanisms underlying appetite and the aetiology of eating disorders characterised by excessive intake of food," concluded the researchers.
The research was welcomed by obesity expert, Dr. Ian Campbell, medical director of the charity Weight Concern, who told FoodNavigator.com that the research was very interesting.
"It quantifies that people are subject to the advertising and promotion of foodstuffs, and some more than others, and that these people are more likely to want to eat," said Dr. Campbell.
Dr. Campbell called on the food industry to take the problem of obesity seriously: "The food industry has a social responsibility to play a role in the solution of this disease called obesity," he said.
For its part, the World Federation of Advertisers (WFA) does appear to be aware of its social responsibilities. In March, the WFA joined the EU Platform for Action on Diet, Physical Activity and Health, which aims to proactively address the incidence of obesity in Europe, particularly in children.
In a statement from the WFA in March, Stephan Loerke, WFA managing director, said: "The promotion of responsible advertising is central to the WFA's activities and we are committed to ensuring the best practice in responsible food and beverage advertising is applied consistently across Europe."
Over 300m adults are obese worldwide, according to latest statistics from the WHO and the International Obesity Task Force. About one-quarter of the US adult population is said to be obese, with rates in Western Europe on the rise although not yet at similar levels.