Research has shown that the more tempting this cake looks to you, the greater the chances you’ll take a bite of real cake, followed by another bite, and another. But what if I told you that viewing this picture as not rewarding enough might also lead you down the path to obesity?
An exciting brain imaging and genetics study from the laboratory of Eric Stice at the Oregon Research Institute, recently published in the journal NeuroImage, has shown just that. Stice’s team had a group of adolescent girls imagine eating appetizing foods while viewing pictures of these foods. Over the following year, those whose brains showed less activation in areas known to respond to natural rewards like foods ended up gaining more weight — though only if they had a particular genetic makeup.
Genetic factors may play a large role in obesity. Some have estimated that 60-70% of the variability in a person’s body mass index or BMI, which is a proxy measure for body fat based on weight and height, is attributable to genetic factors. However, there has been a dramatic increase in the prevalence of obesity over the past 50 years, which is far too little time for changes in the genome to have occurred.
We now find ourselves in what some term an ‘obesogenic’ environment filled with cheap, easily accessible high-calorie foods served in large portions. Genetic risk factors may make some individuals more susceptible to these changes in the environment, and thus more prone to obesity.
But there was another camp of researchers who posited that there was decreased, not increased, reward activity in the brains of obese individuals.
Fewer dopamine D2 receptors result in lower dopamine activity, which has been shown to lead to increased food consumption and weight gain.
So both increased and decreased reward sensitivity could lead to obesity? One labreconciled these seemingly disparate ideas by focusing on sensitivity to reward, a psychobiological trait assumed to be rooted in the dopamine reward system.
Thus, it is possible that the relationship between reward neurocircuitry and obesity follows the Goldilocks principle – too much or too little reward system activation may lead to weight gain. In order to maintain a healthy weight, reward system activation needs to be ‘just right.’
Balance is the keyword for human life both biologically and mentally. With a complex ecosystem balance is the only way to survive and stay efficient