Posts tagged weight loss
Articles and news from the latest research reports.
Training Your Brain to Prefer Healthy Foods
It may be possible to train the brain to prefer healthy low-calorie foods over unhealthy higher-calorie foods, according to new research by scientists at the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University and at Massachusetts General Hospital. Published online today in the journal Nutrition & Diabetes, a brain scan study in adult men and women suggests that it is possible to reverse the addictive power of unhealthy food while also increasing preference for healthy foods.
“We don’t start out in life loving French fries and hating, for example, whole wheat pasta,” said senior and co-corresponding author Susan B. Roberts, Ph.D., director of the Energy Metabolism Laboratory at the USDA HNRCA, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts University and an adjunct professor of psychiatry at Tufts University School of Medicine. “This conditioning happens over time in response to eating – repeatedly! - what is out there in the toxic food environment.”
Scientists have suspected that, once unhealthy food addiction circuits are established, they may be hard or impossible to reverse, subjecting people who have gained weight to a lifetime of unhealthy food cravings and temptation. To find out whether the brain can be re-trained to support healthy food choices, Roberts and colleagues studied the reward system in thirteen overweight and obese men and women, eight of whom were participants in a new weight loss program designed by Tufts University researchers and five who were in a control group and were not enrolled in the program.
Both groups underwent magnetic resonance imaging (MRI) brain scans at the beginning and end of a six-month period. Among those who participated in the weight loss program, the brain scans revealed changes in areas of the brain reward center associated with learning and addiction. After six months, this area had increased sensitivity to healthy, lower-calorie foods, indicating an increased reward and enjoyment of healthier food cues. The area also showed decreased sensitivity to the unhealthy higher-calorie foods.
“The weight loss program is specifically designed to change how people react to different foods, and our study shows those who participated in it had an increased desire for healthier foods along with a decreased preference for unhealthy foods, the combined effects of which are probably critical for sustainable weight control,” said co-author Sai Krupa Das, Ph.D., a scientist in the Energy Metabolism Laboratory at the USDA HNRCA and an assistant professor at the Friedman School. “To the best of our knowledge this is the first demonstration of this important switch.” The authors hypothesize that several features of the weight loss program were important, including behavior change education and high-fiber, low glycemic menu plans.
“Although other studies have shown that surgical procedures like gastric bypass surgery can decrease how much people enjoy food generally, this is not very satisfactory because it takes away food enjoyment generally rather than making healthier foods more appealing,” said first author and co-corresponding author Thilo Deckersbach, Ph.D., a psychologist at Massachusetts General Hospital. “We show here that it is possible to shift preferences from unhealthy food to healthy food without surgery, and that MRI is an important technique for exploring the brain’s role in food cues.”
“There is much more research to be done here, involving many more participants, long-term follow-up and investigating more areas of the brain,” Roberts added. “But we are very encouraged that, the weight loss program appears to change what foods are tempting to people.”
Brain Benefits From Weight Loss Following Bariatric Surgery
Weight loss surgery can curb alterations in brain activity associated with obesity and improve cognitive function involved in planning, strategizing and organizing, according to a new study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).
Obesity can tax the brain as well as other organs. Obese individuals face a 35 percent higher risk of developing Alzheimer’s disease compared to normal weight people.
Bariatric surgery is used to help people who are dangerously obese lose weight. Bariatric surgery procedures are designed to restrict the amount of food you can eat before you feel full by reducing the stomach’s size or limit the absorption of nutrients by removing part of the small intestine from the path food takes through the digestive tract. Some procedures, such as Roux-en-Y gastric bypass (RYBG) surgery, use a combination of these methods. This study was the first to assess brain activity in women before and after bariatric surgery.
“When we studied obese women prior to bariatric surgery, we found some areas of their brains metabolized sugars at a higher rate than normal weight women,” said one of the study’s authors, Cintia Cercato, MD, PhD, of the University of São Paolo in São Paolo, Brazil. “In particular, obesity led to altered activity in a part of the brain linked to the development of Alzheimer’s disease – the posterior cingulate gyrus. Since bariatric surgery reversed this activity, we suspect the procedure may contribute to a reduced risk of Alzheimer’s disease and other forms of dementia.”
The longitudinal study examined the effect of RYBG surgery on the brain function of 17 obese women. Researchers used positron emission tomography (PET) scans and neuropsychological tests to assess brain function and activity in the participants prior to surgery and six months after the procedure. The same tests also were run once on a control group of 16 lean women.
Before they underwent surgery, the obese women had higher rates of metabolism in certain areas of the brain, including the posterior cingulate gyrus. Following surgery, there was no evidence of this exacerbated brain activity. Their brain metabolism rates were comparable to the activity seen in normal weight women.
After surgery, the obese women also performed better on a test measuring executive function – the brain’s ability to connect past experience and present action – than they did before the procedures. Executive function is used in planning, organizing and strategizing. Five other neuropsychological tests measuring various aspects of memory and cognitive function showed no change following the surgery.
“Our findings suggest the brain is another organ that benefits from weight loss induced by surgery,” Cercato said. “The increased brain activity the obese women exhibited before undergoing surgery did not result in improved cognitive performance, which suggests obesity may force the brain to work harder to achieve the same level of cognition.”
(Image: Getty)
Vitamin D Can Lower Weight, Blood Sugar via the Brain
Vitamin D treatment acts in the brain to improve weight and blood glucose (sugar) control in obese rats, according to a new study being presented Saturday at the joint meeting of the International Society of Endocrinology and the Endocrine Society: ICE/ENDO 2014 in Chicago.
“Vitamin D deficiency occurs often in obese people and in patients with Type 2 diabetes, yet no one understands if it contributes to these diseases,” said Stephanie Sisley, MD, the study’s principal investigator and an assistant professor at Baylor College of Medicine, Houston. “Our results suggest that vitamin D may play a role in the onset of both obesity and Type 2 diabetes by its action in the brain.”
“The brain is the master regulator of weight,” Sisley said. A region of the brain called the hypothalamus controls both weight and glucose, and has vitamin D receptors there.
In this study funded by the National Institutes of Health, Sisley and partners at the University of Cincinnati delivered vitamin D directly to the hypothalamus. The investigators administered the active, potent form of vitamin D—called 1,25-dihydroxyvitamin D3—to obese male rats through a cannula (thin tube) surgically inserted using anesthesia into the brain’s third ventricle. This narrow cavity lies within the hypothalamus. Rats recovered their presurgery body weight, and the researchers verified the correct cannula placement.
The animals received nothing to eat for four hours, so they could have a fasting blood sugar measurement. Afterward, 12 rats received vitamin D dissolved in a solution acting as a vehicle for drug delivery. Another 14 rats, matched in body weight to the first group, received only the vehicle, thus serving as controls. One hour later, all rats had a glucose tolerance test, in which they received an injection of dextrose, a sugar, in their abdomen, followed by measurement of their blood sugar levels again.
Compared with the control rats, animals that received vitamin D had improved glucose tolerance, which is how the body responds to sugar. In a separate experiment, these treated rats also had greatly improved insulin sensitivity, the body’s ability to successfully respond to glucose. When this ability decreases—called insulin resistance—it eventually leads to high blood sugar levels. Two of insulin’s main effects are to clear glucose from the bloodstream and decrease glucose production in the liver. In this study, vitamin D in the brain decreased the glucose created by the liver.
In a separate experiment of long-term vitamin D treatment, the researchers gave three rats vitamin D and four rats vehicle alone for four weeks. They observed a large decrease in food intake and weight in rats receiving vitamin D compared with the group that did not get vitamin D. Over 28 days, the treated group ate nearly three times less food and lost 24 percent of their weight despite not changing the way they burned calories, study data showed. The control group did not lose any weight.
“Vitamin D is never going to be the silver bullet for weight loss, but it may work in combination with strategies we know work, like diet and exercise,” Sisley commented.
She said more research is necessary to determine if obesity alters vitamin D transport into the brain or its action in the brain.
(Source: newswise.com)
Weight Loss Improves Memory and Alters Brain Activity in Overweight Women
Memory improves in older, overweight women after they lose weight by dieting, and their brain activity actually changes in the regions of the brain that are important for memory tasks, a new study finds. The results were presented at The Endocrine Society’s 95th Annual Meeting in San Francisco.
(Image: Corbis)
“Our findings suggest that obesity-associated impairments in memory function are reversible, adding incentive for weight loss,” said lead author Andreas Pettersson, MD, a PhD student at Umea University, Umea, Sweden.
Previous research has shown that obese people have impaired episodic memory, the memory of events that happen throughout one’s life.
Pettersson and co-workers performed their study to determine whether weight loss would improve memory and whether improved memory correlated with changes in relevant brain activity. A special type of brain imaging called functional magnetic resonance imaging (functional MRI) allowed them to see brain activity while the subjects performed a memory test.
The researchers randomly assigned 20 overweight, postmenopausal women (average age, 61) to one of two healthy weight loss diets for six months. Nine women used the Paleolithic diet, also called the Caveman diet, which was composed of 30 percent protein; 30 percent carbohydrates, or “carbs”; and 40 percent unsaturated fats. The other 11 women followed the Nordic Nutrition Recommendations of a diet containing 15 percent protein, 55 percent carbs and 30 percent fats.
Before and after the diet, the investigators measured the women’s body mass index (BMI, a measure of weight and height) and body fat composition. They also tested the subjects’ episodic memory by instructing them to memorize unknown pairs of faces and names presented on a screen during functional MRI. The name for this process of creating new memory is “encoding.” Later, the women again saw the facial images along with three letters. Their memory retrieval task, during functional MRI, was to indicate the correct letter that corresponded to the first letter of the name linked to the face.
Because the two dietary groups did not differ in body measurements and functional MRI data, their data were combined and analyzed as one group. The group’s average BMI decreased from 32.1 before the diet to 29.2 (below the cutoff for obesity) after six months of dieting, and their average weight dropped from 188.9 pounds (85 kilograms) to 171.3 pounds (77.1 kilograms), the authors reported. This study was part of a larger, diet-focused study funded by the Swedish Research Council and the Swedish Heart-Lung Foundation.
Memory performance improved after weight loss, and Pettersson said the brain-activity pattern during memory testing reflected this improvement. After weight loss, brain activity reportedly increased during memory encoding in the brain regions that are important for identification and matching of faces. In addition, brain activity decreased after weight loss in the regions that are associated with retrieval of episodic memories, which Pettersson said indicates more efficient retrieval.
“The altered brain activity after weight loss suggests that the brain becomes more active while storing new memories and therefore needs fewer brain resources to recollect stored information,” he said.
(Source: newswise.com)
Is obesity irreversible? Timing is everything when it comes to weight loss
Joint research between the University of Michigan and the Argentina-based National Council of Science and Technology (CONICET) has shed light on one of the most frustrating mysteries of weight loss – why the weight inevitably comes back.
A novel animal model showed that the longer mice remained overweight, the more “irreversible” obesity became, according to the new study that appeared online ahead of print Oct.24 in the Journal of Clinical Investigation.
Over time, the static, obese state of the mice reset the “normal,” body weight set point to become permanently elevated, despite dieting that initially worked to shed pounds, authors say.
“Our model demonstrates that obesity is in part a self-perpetuating disorder and the results further emphasize the importance of early intervention in childhood to try to prevent the condition whose effects can last a lifetime,” says senior author Malcolm J. Low, M.D., Ph.D., professor of molecular and integrative physiology and internal medicine.
(Source: uofmhealth.org)
New gene-therapy approach could improve obesity treatment
Medical researchers at the University of Alberta have found a new way of using gene therapy to treat obesity. The treatment was successful, resulting in less weight gain, higher activity levels and decreased insulin resistance in lab models on a high-fat, high-sugar diet.
Faculty of Medicine & Dentistry researcher Jason Dyck, who works in the Department of Pediatrics and the Department of Pharmacology, published his findings this week in the peer-reviewed journal Nutrition and Diabetes. His team found a way to deliver the obesity treatment via DNA as opposed to a virus, which has had limited success in the past, especially over the long term. The results they demonstrated corroborated findings by other researchers who conducted short-term studies or used more risky methods of gene delivery.
“I think our findings may bring this treatment one step closer to clinical trials, as this approach appears to be much safer than conventional forms of gene therapy,” said Dyck.
The obesity treatment focused on increasing levels of adiponectin, a hormone secreted from fat cells. As a person gains weight and fat cells get larger, the body secretes less of this hormone. People who are thin secrete high levels of this hormone.
“This hormone seems to be protective against a number of diseases, including diabetes and cardiovascular disease, as well as weight gain,” says Dyck. “But as you gain weight, less adiponectin is secreted and you lose the beneficial effects associated with this hormone.”
Lab animal models fed a high-fat, high-sugar diet that were given this treatment gained less weight, burned more calories, were more active, used more oxygen, and were better protected against glucose intolerance and insulin resistance than those that were fed the same diet but didn’t get the anti-obesity treatment. Dyck hopes other research teams will move his work forward.
![Adequate sleep helps weight loss
Adequate sleep is an important part of a weight loss plan and should be added to the recommended mix of diet and exercise, states a commentary in CMAJ (Canadian Medical Association Journal).
Although calorie restriction and increased physical activity are recommended for weight loss, there is significant evidence that inadequate sleep is contributing to obesity. Lack of sleep increases the stimulus to consume more food and increases appetite-regulating hormones.
"The solution [to weight loss] is not as simple as ‘eat less, move more, sleep more,’" write Drs. Jean-Phillippe Chaput, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario and Angelo Tremblay, Laval University, Québec, Quebec. "However, an accumulating body of evidence suggests that sleeping habits should not be overlooked when prescribing a weight-reduction program to a patient with obesity. Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."
The authors’ recently published research found that total sleep time and quality of sleep predicted the loss of fat in people enrolled in a weight loss program.
The Canadian Obesity Network has included adequate sleep in its new set of obesity management tools for physicians.](http://41.media.tumblr.com/tumblr_majgjbN8VU1rog5d1o1_500.jpg)
Adequate sleep helps weight loss
Adequate sleep is an important part of a weight loss plan and should be added to the recommended mix of diet and exercise, states a commentary in CMAJ (Canadian Medical Association Journal).
Although calorie restriction and increased physical activity are recommended for weight loss, there is significant evidence that inadequate sleep is contributing to obesity. Lack of sleep increases the stimulus to consume more food and increases appetite-regulating hormones.
"The solution [to weight loss] is not as simple as ‘eat less, move more, sleep more,’" write Drs. Jean-Phillippe Chaput, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario and Angelo Tremblay, Laval University, Québec, Quebec. "However, an accumulating body of evidence suggests that sleeping habits should not be overlooked when prescribing a weight-reduction program to a patient with obesity. Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."
The authors’ recently published research found that total sleep time and quality of sleep predicted the loss of fat in people enrolled in a weight loss program.
The Canadian Obesity Network has included adequate sleep in its new set of obesity management tools for physicians.
New research from the Hebrew University of Jerusalem shows that a carefully scheduled high-fat diet can lead to a reduction in body weight and a unique metabolism in which ingested fats are not stored, but rather used for energy at times when no food is available.
The results were published in FASEB Journal under the title ‘Timed high-fat diet resets circadian metabolism and prevents obesity.’
Previous research has established that disrupting mammals’ daily rhythms, or feeding them a high-fat diet, disrupts metabolism and leads to obesity. The researchers wanted to determine the effect of combining a high-fat diet with long-term feeding on a fixed schedule. They hypothesized that careful scheduling of meals would regulate the biological clock and reduce the effects of a high-fat diet that, under normal circumstances, would lead to obesity.