The Centers for Disease Control and Prevention in Atlanta, Georgia, estimates that 42% of Americans will be obese by 2030. Obesity remains a huge public health problem, and a billion dollar industry for those marketing a diet plan or “get slim quick” scheme. Most of these are failures, and not worth the money spent.
There is one method of weight loss that seems to have positive results, and not just for the body, but also for the brain.
Surgery is by far the last resort when it comes to weight control, and it is not for everyone. It does offer hope for those who are morbidly obese, suffering from diabetes and other health problems. It seems to work both as a way to “re-plumb the gut” and rewire the brain.
All bariatric surgeries work basically the same principle, by reducing the amount of food the body can absorb. In the U.S., currently 36 % of the population is classified as obese, and of these people at least 200,000 people sign up annually to have the surgery. That is because it works! Most who have the surgery find their weight melts off within 18 months. This is a much better success rate than diet pills.
Originally, the success of this surgery was thought to be that by simply not being able to eat as much the patient would lose weight. There was a flaw in that logic, however, because high calorie foods were still available in soups, milkshakes and liquid forms. Eating was not the problem, and a liquid diet was not a solution.
Many people can take weight off, but soon find it comes back, with even more of its friends. Doctors will advise long-term weight loss can only be obtained by exercise and eating fewer calories and less fat. This may be a good idea, but it’s only a temporary solution to those with the “dieting” mentality. As soon as they become depressed or disappointed they begin to eat high sugar content food again, and the weight returned.
Those who were able to keep their weight off did so for other reasons. One of them was a change in their taste buds and food preferences. Somehow, our bodies are hard-wired to crave unhealthy foods, and this craving is accelerated after we diet to lose the weight.
Those who have had bariatric surgery don’t have the same cravings anymore. “People who have lost weight after surgery don’t report a compensatory increase in food cravings or hunger the way dieting people do,” says Stephen Benoit, a behavioral neuroscientist at the University of Cincinnati, Ohio, who studies obesity. Quite the opposite: they tend to report reduced levels of hunger, fewer food cravings and an overall altered relationship with food.
Within hours of any weight-loss surgery, many people can’t stand the taste of sugar or fat, and sometimes find the very smell offensive, says Carel le Roux, a bariatric endocrinologist at the Imperial Weight Centre in London. For Roux-en-Y, the effects linger. “In the long-term, we find people shifting their food preferences and going for the salad bar instead of a burger and fries,” he says.
Is this change psychological or physiological? In order to know for sure, le Roux and his colleagues put together a test find out why these behavioral changes are taking place.
They performed bariatric Roux-en-Y surgery on rats and then tested their subsequent food preferences. Like so many of their human counterparts, the rats almost instantly shifted their tastes to favor lower-fat, lower-sugar items. “These rats had never met a dietician,”” says le Roux, “so it wasn’t as though they were suddenly more motivated to make healthier choices because they had surgery.”
Now that they ascertained the changes were physiological they wanted to know what could be causing this change. One obvious place to start would be the hormones generated by the digestive system. The upper stomach, for example, produces a powerful hunger-promoter called ghrelin. The small intestine releases a number of appetite-suppressing hormones that are supposed to tell you when you are full, including glucagon-like peptide-1 (GLP-1) and peptide YY, or PYY. Even fat cells play a part in regulating appetite by releasing leptin, a hormone that inhibits the desire to eat and regulates metabolism.
Major hormones are radically altered during weight-loss surgery. “Gastrointestinal hormones and leptin levels change, and do so in a favorable direction,” says Lauren Beckman, a researcher at the University of Minnesota in Minneapolis who is studying hormonal changes in people who have had bariatric surgery. Rearranging the stomach also lowers the production of appetite-stimulating ghrelin, which might explain why many surgery recipients have to force themselves to eat. Hunger levels are also lowered by a spike in Leptin production.
Beckman believes these changes trigger the rapid weight loss, since normally these elevated hormone levels would not kick in for at least a month after surgery. Instead, she and other researchers are finding that concentrations of appetite-suppressing GLP-1 and PYY increase within about two days, and stay that way for at least a year or two.
Recent animal studies have found even more interesting effects of these hormonal changes, that they can disrupt the synaptic plasticity and the nervous system, mechanisms that affect structural and functional brain changes. For example, ghrelin alters the wiring of mouse neurons.
GLP-1 suppresses the appetite by lowering blood sugar; it appears to have a strong effect on insulin, whose production drops dramatically within hours of surgery. Lower insulin levels, in turn, reduce the insulin resistance caused by excess weight, which has itself been tied to neurological problems.
A recent press release indicates that almost immediately after bariatric surgery patients with diabetes no longer had the disease, and after two years still did not show signs of the disease.
Some researchers believe that by simply balancing the sugar levels in the blood enhances memory and cognitive function.
There are also negative effects to the brain. According to Keith Josephs, a neurologist at Mayo Clinic in Rochester, Minnesota, many patients who had Roux-en-Y bariatric surgery have come to him complaining of cognitive problems. “They were coming to me with issues like having trouble finding the right word, difficulty concentrating at work, being slow to respond to people talking to them and short-term memory issues,” he says.
MRI scans conducted showed that those reporting cognitive problems had 24% less volume in the thalamus, a small area of the brain associated with memory, attention, concentration and sensory information about taste. In particular, the thalamus contains binding sites for ghrelin and GLP-1.
Large changes in these hormones could affect this brain area in the same way they alter the reward centers. And just as the positive changes in food preference appear not to be temporary, so do these negative changes. “Once the thalami have shrunk, there is nothing we can do to re-grow these nerve cells,” Josephs says.
Weight-loss surgery can be a life-saving procedure: it can knock out diabetes, high blood pressure and sleep apnea, among other conditions that can make your blood flow better and your brain work brighter. There also can be some side effects that can not be reversed, so it needs to be a last resort solution, and one someone should know all the pros and cons before they agree to proceed.
About the author:
Ron White is a two-time U.S.A. Memory Champion and memory training expert.
Sources:
I’ve Got Friends in Low-Carb Places – Change Your Stomach, Change Your Brain, by Samantha Murphy: http://forum.lowcarber.org/showthread.php?t=442629
International Journal of Obestity – Food Reward functions as affected by obesity and bariatric surgery: http://www.nature.com/ijo/journal/v35/n3s/full/ijo2011147a.html
U.S. National Library of Medicine, National Institutes of Health – Ghrelin in the CNS: From hunger to a rewarding and memorable meal? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2494866/?tool=pubmed
