For most of us, the biggest problem with losing lots of weight is the demoralizing process of watching ourselves gain it all back. But some people who lose weight manage to keep it off for good. How do they do it? Researchers from the Miriam Hospital recently examined their brain activity with functional magnetic resonance imaging and actually saw their restraint in action.
Functional magnetic resonance imaging, or fMRI, reveals what parts of the brain are working, based on the increase in blood flow to those portions of the brain. Consequently, it enables researchers to determine which brain structures are involved in specific mental operations. Once they have figured out which brain structures correspond to which mental processes, they can use fMRI to see which of those processes are going on during various activities.
The Miriam Hospital researchers wanted to determine which brain functions are activated when long-term weight-loss maintainers are presented with food. So they divided their subjects into three groups: 18 people of normal weight, 16 obese individuals, and 17 participants who had lost at least 30 pounds and had maintained that weight loss for at least three years. After the participants had fasted for four hours and were nicely hungry, the researchers showed them pictures of low-calorie foods, pictures of high-calorie foods, and a few pictures of rocks and shrubs just for the sake of comparison. Then they used the fMRI to peer into their brains and see which regions of their brains were activated in response to each image.
What they found was that the people who had kept the weight off showed much more activity in the left superior frontal and right middle temporal regions of the brain. Those regions are associated with greater inhibitory control and greater visual attention. In short, it appears that the long-term weight-loss maintainers were examining the food closely to see if it had a lot of calories, and if it did, they were marshalling their resources to not eat it.
What the researchers don’t know yet is whether these people were born with their ability to restrain themselves, or whether they developed it throughout years of practice. More research, say the researchers, is called for.
Jeanne McCaffery, PhD, of the Miriam Hospital’s Weight Control and Diabetes Research Center and her team published their findings in the American Journal of Clinical Nutrition.
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