The Overeating MutationBy Peter Liu [Weight Loss]
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Do you overeat because you’re hungry or because you can’t help it? Peter Liu feeds your curiosity about the mutation you may have.  For those of us who like to eat, it’s easy to imagine putting away a slice of pizza or three, but when eating becomes overeating, the cause is usually our appetite and overindulgence in food. For those who are overweight or obese, overeating can have several causes, but, unfortunately, is usually attributed to overindulgence, which makes sense. After all, if it feels good, why not do it? Eating makes us feel good; even some of our favourite memories are tied to tastes and sensations associated with food. Which is why appetite and eating are associated with pleasure, meaning dopamine could be connected to why we overeat. For those who are overweight, a new study suggests dopamine levels could hold the link.Lengthy Milkshake Study Lead study author and senior researcher Dr. Eric Stice of the Oregon Research Institute has been playing around with dopamine research and his findings could shed light on the overeating problem some obese people deal with. Published in the October issue of the journal Science, psychologists in Texas, Oregon and Connecticut believe they can predict future weight gain in women based on their study on dopamine levels in obese women versus leaner women. The purpose of the study was to determine whether obese women had fewer dopamine receptors and therefore, lower dopamine levels. Researchers believe that obese women overeat because it takes more food for dopamine levels to compensate, that is, obese people take less pleasure from eating and may need to eat more to feel good. The brain’s core for dopamine is called the dorsal striatum, dopamine being the neurotransmitter that’s released when we feel good. Using functional Magnetic Resonance Imaging (MRI) scans to measure brain activity, 76 young women were subjected to several taste tests with chocolate milkshakes and a tasteless solution. The women included 43 overweight and obese university students at a mean age of 20 and 33 lean to overweight teens at a mean age of 15. They were asked to join in a study to analyze the neural response to presentations of food. Binge eaters, anorexics or those with eating disorders, illegal drug users and those with psychiatric disorders were excluded from the study. The Process The women were asked to eat their meals regularly, but were also asked not to have any food or drink for four to six hours before their MRI scans for the sake of standardization. The four to six hour period was designed to induce hunger for study purposes. Scans were taken while the women were given visual cues of a milkshake or a glass of water while fed bits of either chocolate milkshake, a tasteless solution mimicking the taste of saliva or nothing at all. The milkshake test was designed to test and study the brain’s anticipation of reward and the receiving of reward, so the visual and taste cues were randomized. There were different test cues, like a visual milkshake cue followed by a squirt of milkshake, a visual water cue followed by the tasteless solution or a visual milkshake cue followed by nothing. The test was repeated to compare study results and the visual cues were replaced by geometric shapes like a diamond, a circle and a square. The women also underwent a test for a genetic variation called the Taq1a1 allele, which is inside a dopamine receptor named DRD2 and dulls the brain’s response to dopamine. |
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