Links for Keyword: Obesity

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Jennifer Couzin-Frankel What if you could trick your body into thinking you were racing on a treadmill—and burning off calories at a rapid clip—while simply walking down the street? Changing our rate of energy expenditure is still far into the future, but work in mice explores how this might happen. Two teams of scientists suggest that activating immune cells in fat can convert the tissue from a type of fat that stores energy to one that burns it, opening up potential new therapies for obesity and diabetes. There are two types of fat in humans: white adipose tissue, which makes up nearly all the fat in adults, and brown adipose tissue, which is found in babies but disappears as they age. Brown fat protects against the cold (it’s also common in animals that hibernate), and researchers have found that mice exposed to cold show a temporary “browning” of some of their white fat. The same effect occurred in preliminary studies of people, where the browning—which creates a tissue known as beige fat—helps generate heat and burn calories. But cold is “the only stimulus we know that can increase beige fat mass or brown fat mass,” says Ajay Chawla, a physiologist at the University of California (UC), San Francisco. He wanted to better understand how cold caused this change in the tissue and whether there was a way to mimic cold and induce browning some other way. A few years ago, Chawla’s group had reported that cold exposure activated macrophages, a type of immune cell, in white adipose tissue. To further untangle what was going on, Chawla, his postdoc Yifu Qiu, and their colleagues used mice that lacked interleukin-4 (IL-4) and interleukin-13, proteins that help activate macrophages. When they exposed these mice to the cold, the animals developed far fewer beige fat cells than did normal animals, suggesting that macrophages were key to browning of white fat. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19732 - Posted: 06.14.2014

by Lauren Hitchings Being cold can burn calories but no one wants to freeze just to sculpt their muffin-top. Soon we may not have to. Researchers have identified immune molecules triggered by cold temperatures that make obese mice lose weight – without the need for the mercury to drop. Humans and other mammals respond to cold in two ways. On the surface, we shiver to burn energy and produce a quick burst of heat. On a deeper level, as Ajay Chawla at the University of California, San Francisco, and his colleagues recently discovered, cold temperatures send signals to immune molecules called macrophages. They, in turn, release other molecules that convert energy-storing white fat into another type that burns energy. Babies and some hibernating animals have lots of these energy-burning cells – known as brown fat – but it almost all disappears as people age. We now know that cold temperatures can trigger a "browning" of white fat in adults – converting some of their white fat into an intermediate form called beige fat. It may seem counterintuitive for our bodies to use up fat stores when we get cold, but think of the white fat as the wooden walls of a log cabin – having them there is a good way to keep warm generally, but when the cold sets in, you're going to want firewood – brown or beige fat, to burn. Now Chawla's team have identified interleukin-4 and interleukin-13 as the signalling molecules that kick-start the transition of white fat to its darker counterpart. What's more, by injecting mice with interleukin-4 four times over a period of eight days, the team was able to bypass the physical cold stimulus and activate the pathway biochemically. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19719 - Posted: 06.10.2014

Jennifer Couzin-Frankel What if you could trick your body into thinking you were racing on a treadmill—and burning off calories at a rapid clip—while simply walking down the street? Changing our rate of energy expenditure is still far into the future, but work in mice explores how this might happen. Two teams of scientists suggest that activating immune cells in fat can convert the tissue from a type of fat that stores energy to one that burns it, opening up potential new therapies for obesity and diabetes. There are two types of fat in humans: white adipose tissue, which makes up nearly all the fat in adults, and brown adipose tissue, which is found in babies but disappears as they age. Brown fat protects against the cold (it’s also common in animals that hibernate), and researchers have found that mice exposed to cold show a temporary “browning” of some of their white fat. The same effect occurred in preliminary studies of people, where the browning—which creates a tissue known as beige fat—helps generate heat and burn calories. But cold is “the only stimulus we know that can increase beige fat mass or brown fat mass,” says Ajay Chawla, a physiologist at the University of California (UC), San Francisco. He wanted to better understand how cold caused this change in the tissue and whether there was a way to mimic cold and induce browning some other way. A few years ago, Chawla’s group had reported that cold exposure activated macrophages, a type of immune cell, in white adipose tissue. To further untangle what was going on, Chawla, his postdoc Yifu Qiu, and their colleagues used mice that lacked interleukin-4 (IL-4) and interleukin-13, proteins that help activate macrophages. When they exposed these mice to the cold, the animals developed far fewer beige fat cells than did normal animals, suggesting that macrophages were key to browning of white fat. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19709 - Posted: 06.07.2014

By GRETCHEN REYNOLDS If you are aiming to lose weight by revving up your exercise routine, it may be wise to think of your workouts not as exercise, but as playtime. An unconventional new study suggests that people’s attitudes toward physical activity can influence what they eat afterward and, ultimately, whether they drop pounds. For some time, scientists have been puzzled — and exercisers frustrated — by the general ineffectiveness of exercise as a weight-loss strategy. According to multiple studies and anecdotes, most people who start exercising do not lose as much weight as would be expected, given their increased energy expenditure. Some people add pounds despite burning hundreds of calories during workouts. Past studies of this phenomenon have found that exercise can increase the body’s production of appetite hormones, making some people feel ravenous after even a light workout and prone to consume more calories than they expended. But that finding, while intriguing, doesn’t fully explain the wide variability in people’s post-exercise eating habits. So, for the new study, published in the journal Marketing Letters, French and American researchers turned to psychology and the possible effect that calling exercise by any other name might have on people’s subsequent diets. In that pursuit, the researchers first recruited 56 healthy, adult women, the majority of them overweight. The women were given maps detailing the same one-mile outdoor course and told that they would spend the next half-hour walking there, with lunch to follow. Half of the women were told that their walk was meant to be exercise, and they were encouraged to view it as such, monitoring their exertion throughout. The other women were told that their 30-minute outing would be a walk purely for pleasure; they would be listening to music through headphones and rating the sound quality, but mostly the researchers wanted them to enjoy themselves. When the women returned from walking, the researchers asked each to estimate her mileage, mood and calorie expenditure. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 11: Emotions, Aggression, and Stress
Link ID: 19691 - Posted: 06.04.2014

By SANFORD E. DeVOE IN recent years we have seen plenty of studies of the impact of fast food on our bodies. But what about our psychological health? It stands to reason that fast food would have an effect on our mental state. From its production to its consumption, fast food both embodies and symbolizes speed and instant gratification. Moreover, through extensive franchising and large advertising budgets, fast-food companies shape many of the cues in our everyday environment. While the ubiquity of fast food is undoubtedly driven by consumer demand for instant gratification, it may also play a role in exacerbating that very impatience — and not just for food, but in many facets of our lives. In a series of recent papers, I joined two of my colleagues at the University of Toronto, Julian House and Chen-Bo Zhong, in examining this question. We began our experiments by prompting participants with reminders of fast food, like pictures of fast-food logos or having them recall recent experiences of eating fast food. We then gave them a number of tasks to complete. Across several studies, we found that thoughts of fast food spurred participants to hurry through reading a paragraph describing their city; express a greater desire for timesaving products; report less happiness from savoring a beautiful opera duet; and save less for tomorrow. These findings — that our associations with fast food can induce greater impatience — are interesting in their own right, but they are especially important because of the pervasiveness of fast food in our modern environment. We also took our investigation a step further, to consider whether the prevalence of fast-food restaurants in our neighborhoods might undercut our well-being. There is a lengthy epidemiology literature demonstrating a link between the number of fast-food restaurants and obesity. While the consequences of fast food for our health seem quite obvious, we wondered what these same methods might reveal regarding impatience. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19680 - Posted: 06.02.2014

By NICHOLAS BAKALAR Several observational studies have suggested that drinking diet soda may encourage weight gain, but a new randomized trial finds that it is not so. The study, published in the June issue of Obesity and paid for by the American Beverage Association, suggests that diet drinks may be better for weight loss than plain water. The study tested 303 men and women who followed the same diet for 12 weeks. But half were randomly assigned to drink at least 24 ounces of water daily, and the rest the same amount of artificially sweetened drinks. After controlling for age, sex, ethnicity and initial weight and blood pressure, researchers found that those who drank diet drinks lost an average of 14.2 pounds, compared with a 10-pound loss for the water drinkers. The mechanism, the authors write, is unclear, but the group on diet drinks reported slightly lower scores on a questionnaire measuring the degree of feelings of hunger. “There’s no magic in diet soda,” said the lead author, James O. Hill, a professor of health and wellness at the University of Colorado. But the less intense feelings of hunger among the drinkers, he said, may have made it easier for them to adhere to the diet. “From everything we know about diet soda,” he continued, “this result was totally expected. There’s not a single randomized controlled trial that shows the opposite.” © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19677 - Posted: 05.31.2014

By ANAHAD O'CONNOR Americans have long been told that the cure for obesity is simple: Eat fewer calories and exercise more. But a new documentary challenges that notion, making the case that Americans have been misled by the idea that we get fat simply because we consume more calories than we expend. The film explores what it sees as some of the more insidious corporate and political forces behind the rise of childhood obesity, and it examines whether increasing levels of sugar consumption have played an outsized role in the epidemic. The film, called “Fed Up,” has as executive producers Katie Couric, the former anchor of “The CBS Evening News,” and Laurie David, who was also a producer of the global warming documentary “An Inconvenient Truth.” Ms. Couric, who narrates the film, said she came up with the idea after years of covering the obesity epidemic left her with more questions than answers. “What struck me was that the more I reported on childhood obesity and the longer I was in this business, the worse the problem seemed to be getting,” Ms. Couric said in an interview. “I felt like we were never really giving people a handle on what was causing this and why the rates were skyrocketing the way they were.” The film draws on commentary from obesity experts and nutrition scientists, and it tells the stories of several obese children around the country who struggle to lose weight despite strict dieting and in some cases hours of daily exercise. But at the heart of the film is a question that is widely debated among scientists: Are all calories equal? Dr. David Ludwig, the director of the obesity program at Boston Children’s Hospital, argues in the film that they are not. In recent studies, Dr. Ludwig has shown that high-carbohydrate diets appear to slow metabolic rates compared to diets higher in fat and protein, so that people expend less energy even when consuming the same number of calories. Dr. Ludwig has found that unlike calories from so-called low glycemic foods (like beans, nuts and non-starchy vegetables), those from high glycemic foods (such as sugar, bread and potatoes) spike blood sugar and stimulate hunger and cravings, which can drive people to overeat. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19596 - Posted: 05.10.2014

Brian Owens Surveys of people's eating habits have suggested a link between fibre intake and weight loss, but exactly how fibre helps to regulate weight has been unclear. A study of mouse metabolism suggests that a product of fibre fermentation may be directly affecting the hypothalamus, a region of the brain involved in regulating appetite. People have long been told that a diet high in fibre can help to fight obesity, but how it does so has been unclear. “There has been lots of epidemiological information showing a relationship between fibre and obesity, but no one has been able to connect the epidemiological results with actual mechanisms,” says Jimmy Bell, a biochemist at Imperial College London who worked on the research, published today in Nature Communications1. Until now, a high-fibre diet was thought to help keep weight down by stimulating the release of appetite-suppressing hormones in the gut2, says Bell, but humans do not seem to show the same increase in these hormones that mice do. So Bell and his colleagues decided to look elsewhere. An obvious candidate, they thought, might be one of the products of fibre fermentation in the gut. In particular they focused on the short-chain fatty acid acetate, because it is the most abundant and is known to circulate throughout the bloodstream. They fed mice fibre labelled with carbon-13, which has an additional neutron from the more common carbon-12 that gives its nuclei a magnetic spin and therefore makes it easy to track as it progresses through the body's chemical reactions. The fibre was fermented as usual into acetate, which turned up not only in the gut, but also in the hypothalamus, a part of the brain known to be involved in regulating appetite. There, the researchers found, it was metabolized through the glutamine-glutamate cycle, which is involved in controlling the release of neurotransmitters associated with appetite control. The same model has been proposed for acetate metabolism after drinking alcohol. © 2014 Nature Publishing Group,

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19557 - Posted: 04.30.2014

By Lenny Bernstein FILE - In this Oct. 7, 2013 file photo, workers collect red grapes in the vineyards of the famed Chateau Haut Brion, a Premier Grand Cru des Graves, during the grape harvest in Pessac-Leognan, near Bordeaux, southwestern France. Global warming makes feeding the world harder and more expensive, a United Nations scientific panel said. A warmer world will push food prices higher, trigger Red wine gets all the good press for the cardiovascular benefits of the flavonoids it contains, but U.S. Department of Agriculture researchers are reporting that one white wine grape has the reds beat when it comes to slowing weight gain and lowering cholesterol, at least in laboratory animals. The researchers put hamsters on a high-fat diet supplemented by flour made from the seeds of grapes used for chardonnay, syrah and cabernet sauvignon wines. They found that the white grapes easily beat the reds in slowing the hamsters’ weight gain and limiting production of cholesterol. They believe the higher levels of flavonoids in the chardonnay grape seeds altered the work of genes related to fat metabolism. They also had an anti-inflammatory effect, according to a study the USDA scientists published in the Journal of Agricultural and Food Chemistry in February. In part, the researchers say in another paper yet to be published, the anti-oxidant compounds in the chardonnay grape seeds may work with bacteria in the gut to produce beneficial effects. The flour production also provides grape-growers a way to use seeds that currently are discarded and dumped during the chardonnay production. The Mayo Clinic has begun human trials to determine whether the same results can be achieved, said Wally Yokoyama, a research chemist for the USDA in Albany, Calif., and one of the authors of the two studies. The innovation is one of many in a new USDA report released this week. © 1996-2014 The Washington Post

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19545 - Posted: 04.29.2014

By LAWRENCE K. ALTMAN Douglas L. Coleman, a Canadian-born scientist who upset scientific dogma by discovering that genes — not willpower, eating habits or other behaviors — could cause obesity in some people, died on April 16 at his home in Lamoine, Me. He was 82. The cause was aggressive basal cell cancer, said a spokeswoman for the Jackson Laboratory in Bar Harbor, Me., where Dr. Coleman spent his entire research career. Beginning in the 1960s, Dr. Coleman’s research showed that a blood-borne substance could curb hunger. In the 1990s, his findings led Dr. Jeffrey M. Friedman’s team at the Rockefeller University in Manhattan to identify the gene that produces the appetite suppressant leptin, which is released by fat cells. For their work, Dr. Coleman and Dr. Friedman shared the prestigious Lasker Award for basic medical research in 2010. Their discoveries upended the conventional wisdom that fat cells are simply energy storage bins, and demonstrated that fat tissue is an endocrine organ required for normal development. Scientists have learned from their research and others’ that fat produces a variety of hormones, cytokines and other chemicals in the body’s natural weight-control system. Douglas Leonard Coleman was born on Oct. 6, 1931, in Stratford, Ontario. Influenced by his father, Leonard, who repaired radios and refrigerators for a living, Douglas spent much of his youth investigating how things worked by taking them apart. He earned a chemistry degree from McMaster University in Hamilton, Ontario, and a doctorate in biochemistry from the University of Wisconsin. In 1958, facing poor employment prospects in academia or industry in Canada, he became a research scientist at the Jackson Laboratory, which studies mouse genetics to learn about human disease. He intended to spend a year or two there to gain experience in genetics and immunology, but stayed until he retired in 1991. After retiring, he turned a tract of land he owned into a nature preserve. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19538 - Posted: 04.26.2014

Victoria Colliver, Erin Allday Women who gain too much or too little weight during pregnancy can greatly increase their baby's risk of being overweight or obese as a young child, according to a study by Kaiser Permanente researchers. Researchers examined the health records from 4,145 Northern California Kaiser members who filled out a health survey between 2007 and 2009 and subsequently gave birth. They found that women who exceeded the Institute of Medicine's revised 2009 guidelines for weight gain during pregnancy were 46 percent more likely than women who met the guidelines to have an obese or overweight child between the ages of 2 and 5 years old. Under the new guidelines, women who are obese - defined as those with a body mass index, or BMI, of 30 or higher - should gain 11 to 20 pounds. Overweight women - with BMIs between 25 and 29 - can gain 15 to 25 pounds. And normal-weight women are recommended to gain between 25 and 35 pounds. Those who are underweight - with BMIs under 18.5 - are to gain 28 to 40 pounds. Women who had a healthy BMI before their pregnancy but gained less weight than recommended were 63 percent more likely than those who met the guidelines to have an obese or overweight child. Meanwhile, healthy-weight women who exceeded the guidelines were 79 percent more likely to have an overweight child. Researchers suggested gaining too little or too much weight may permanently affect the body's mechanisms that manage energy balance and metabolism. The study, which is considered the largest to examine the new guidelines in relationship to childhood obesity, was published April 14 in the American Journal of Obstetrics and Gynecology. © 2014 Hearst Communications, Inc.

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory, Learning, and Development
Link ID: 19524 - Posted: 04.23.2014

By SABRINA TAVERNISE WASHINGTON — Researchers at the University of North Carolina published a paper last week that introduced another wrinkle into the debate about childhood obesity. They disputed recent findings that obesity among young children had fallen since 2004, arguing that a longer view — using data all the way back to 1999 — showed that these youngsters were not really getting any thinner. So which view is correct? The answer seems to be both. Obesity has become a major health problem in the United States, affecting about 17 percent of Americans ages 2 to 19, up from about 5 percent in the early 1970s. The rate rose for years but then leveled off, and the current debate centers on whether obesity has begun to decline in the youngest of these children. The question has drawn considerable attention not just because scientists disagree on the answer, but also because it has a political dimension: The issue has been vigorously championed by Michelle Obama, the first lady. The North Carolina researchers and the federal team that produced the earlier findings both relied on the same data from the National Health and Nutrition Examination Survey. It is considered the gold standard in health research because height and weight are measured by a health professional, not the respondents themselves. But instead of looking only at the past decade of data on children ages 2 to 5, the North Carolina researchers looked at 14 years’ worth. An unusual spike in obesity among these children in 2003 created the false appearance of a later decline, they concluded, so comparing 2012 to 1999 gave a truer view of the trends. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19487 - Posted: 04.15.2014

by Alix Spiegel It was late, almost 9 at night, when Justin Holden pulled the icy pizza box from the refrigerator at the Brookville Supermarket in Washington, D.C. He stood in front of the open door, scanning the nutrition facts label. A close relative had recently had a heart attack, and in the back of his mind there was this idea stalking him: If he put too much salt in his body, it would eventually kill him. For this reason the information in the label wasn't exactly soothing: 1,110 milligrams of sodium seemed like a lot. But there was even worse-sounding stuff at the bottom of the label. Words like "diglyceride," with a string of letters that clearly had no business sitting next to each other. It suggested that something deeply unnatural was sitting inside the box. "Obviously it's not good for me," the 20ish Holden said. "But, hopefully, I can let it slide in." He tucked the pizza under his arm, and headed one aisle over for a sports drink. Who among us has not had a moment like this? That intimate tete-a-tete with the nutrition label, searching out salt, sugar, fat, trying to discern: How will you affect me? Are you good? Or are you bad? Here's the thing you probably haven't stopped to consider: how the label itself is affecting you. "Labels are not just labels; they evoke a set of beliefs," says , a clinical psychologist who does research at the Columbia Business School in New York. A couple of years ago, Crum found herself considering what seems like a pretty strange question. She wanted to know whether the information conveyed by a nutritional label could physically change what happens to you — "whether these labels get under the skin literally," she says, "and actually affect the body's physiological processing of the nutrients that are consumed." ©2014 NPR

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Attention and Consciousness
Link ID: 19486 - Posted: 04.15.2014

Erika Check Hayden Monkeys on a reduced-calorie diet live longer than those that can eat as much as they want, a new study suggests. The findings add to a thread of studies on how a restricted diet prolongs life in a range of species, but they complicate the debate over whether the research applies to animals closely related to humans. In the study, which has been running since 1989 at the Wisconsin National Primate Research Center in Madison, 38 rhesus macaques (Macaca mulatta) that were allowed to eat whatever they wanted were nearly twice as likely to die at any age than were 38 monkeys whose calorie intakes were cut by 30%1. The same study reported2 in 2009 that calorie-restricted monkeys were less likely to die of age-related causes than control monkeys, but had similar overall mortality rates at all ages. “We set out to test the hypothesis: would calorie restriction delay ageing? And I think we've shown that it does,” says Rozalyn Anderson, a biochemist at the University of Wisconsin who led the study, which is published today in Nature Communications. She said it is not surprising that the 2009 paper did not find that the calorie-restricted monkeys lived longer, because at the time too few monkeys had died to prove the point. Eating a very low-calorie diet has been shown3 to prolong the lives of mice, leading to speculation that such a diet triggers a biochemical pathway that promotes survival. But what that pathway might be — and whether humans have it — has been a matter of hot debate. Eat to live In 2012, a study at the US National Institute on Aging (NIA) in Bethesda, Maryland, cast doubt on the idea, reporting4 that monkeys on low-calorie diets did not live longer than those that ate more food. But Anderson says that the Wisconsin findings are good news. © 2014 Nature Publishing Group

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19439 - Posted: 04.02.2014

|By Meredith Knight Add another credential to oxytocin's impressive resume: the hormone crucial for bonding also reduces the calories people consume when they are snacking for pleasure, making it a possible therapeutic target for obesity. German researchers gave a group of men a dose of oxytocin thought to be roughly the amount released by the brain after breast-feeding or sex, according to lead author Manfred Hallschmid of the University of Tübingen. These men and another group who took a placebo then had a chance to eat as much as they wanted at a breakfast buffet, and later the same day they were offered snacks. Those who took oxytocin ate fewer snack calories, but the hormone did not change how much the men ate during the main meal, suggesting that oxytocin affected pleasure eating without suppressing normal appetite mechanisms. The researchers hypothesize that the hormone diminished reward-seeking behavior initiated in the ventral tegmental area of the brain, a region found to be highly sensitive to oxytocin in rodent studies. The effect may also be stress-related: subjects who took oxytocin saw a drop in their levels of the stress hormone cortisol, according to the paper published in 2013 in the journal Diabetes. More work is needed to understand whether oxytocin could be used to treat obesity, but until then the finding at least hints that it may be possible to curb your cravings by having more sex. © 2014 Scientific American

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 8: Hormones and Sex
Link ID: 19365 - Posted: 03.15.2014

Brian Owens Scientists studying what they thought was a ‘fat gene’ seem to have been looking in the wrong place, according to research published today in Nature1. It suggests instead that the real culprit is another gene that the suspected obesity gene interacts with. In 2007, several genome studies identified mutations in a gene called FTO that were strongly associated with an increased risk of obesity and type 2 diabetes in humans. Subsequent studies in mice showed a link between the gene and body mass. So researchers, including Marcelo Nóbrega, a geneticist at the University of Chicago, thought that they had found a promising candidate for a gene that helped cause obesity. The mutations were located in non-coding portions of FTO involved in regulating gene expression. But when Nóbrega looked closer, he found that something was amiss. These regulatory regions contained some elements that are specific for the lungs, one of the few tissues in which FTO is not expressed. “This made us pause,” he says. “Why are there regulatory elements that presumably regulate FTO in the tissue where it isn’t expressed?” This was not the first red flag. Previous attempts to find a link between the presence of the obesity-associated mutations and the expression levels of FTO had been a “miserable failure”, he says. When Nóbrega presented his new results at meetings, he adds that many people came to him to say ‘I just knew there was something wrong here’. So Nóbrega’s team cast the net wider, looking for genes in the broader neighbourhood of FTO whose expression matched that of the mutations, and found IRX3, a gene about half a million base pairs away. IRX3 encodes a transcription factor — a type of protein involved in regulating the expression of other genes — and is highly expressed in the brain, consistent with a role in regulating energy metabolism and eating behaviour. © 2014 Nature Publishing Group

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19362 - Posted: 03.13.2014

Think you’ll always pick chocolate over a bag of chips? Don’t be so sure. Researchers have found that if they can get people to pay more attention to a particular type of junk food, they will begin to prefer it—even weeks or months after the experiment. The finding suggests a new way to manipulate our decisions and perhaps even encourage us to pick healthy foods. “This paper is provocative and very well done,” says Antonio Rangel, a neuroeconomist at the California Institute of Technology in Pasadena, who was not involved in the new study. “It is exciting because it’s a proof of concept that a relatively simple intervention can have this long-lasting effect.” Economists who study decision-making had previously found that, when deciding between multiple items, people tend to let their gaze linger on the things that they end up choosing. This observation has motivated companies to pursue flashy packaging to attract consumers’ eyes. Tom Schonberg, a neuroscientist at the University of Texas, Austin, wondered whether people’s preferences could be changed before being faced with such a decision by training their brains to pay more attention to certain items. His first task was figuring out what kind of junk food people preferred. He and his colleagues recruited more than 200 university students and set up an auction-style program that asked them how much they were willing to pay for 60 different kinds of snacks, from M&M’s to Fritos. Then, the participants went through a 30- to 50-minute computer training program that showed photos of foods that the participants had already rated. When some treats appeared on the screen, a short tone would play and signal the subject to press a button as fast as possible. When other treats popped up, the computer remained silent and the subject refrained from pressing the button. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Attention and Consciousness
Link ID: 19338 - Posted: 03.10.2014

By Debra Weiner An active lifestyle improves brain health, scientists have long believed. The studies bear this out: physical, intellectual and social activity—or “environmental enrichment,” in the parlance—enhances learning and memory and protects against aging and neurological disease. Recent research suggests one benefit of environmental enrichment at the cellular level: it repairs brain myelin, the protective insulation surrounding axons, or nerve fibers, which can be lost because of aging, injury or diseases such as multiple sclerosis. But how does an enriched environment trigger myelin repair in the first place? The answer appears to involve naturally occurring membrane-wrapped packets called exosomes. A number of different cell types release these little sacs of proteins and genetic material into the body's fluids. Loaded with signaling molecules, exosomes spread through the body “like messages in a bottle,” says R. Douglas Fields, a neurobiologist at the National Institutes of Health. They target particular cells and change their behavior. In animal studies, exosomes secreted by immune cells during environmental enrichment caused cells in the brain to start myelin repair. Researchers think exosomes might find use as biomarkers for diagnosing diseases or as vehicles to deliver cancer drugs or other therapeutic agents. The exosomes produced during environmental enrichment carry microRNAs—small pieces of genetic material—which appear to instruct immature cells in the brain to develop into myelin-making cells called oligodendrocytes. When researchers at the University of Chicago withdrew exosomes from the blood of rats and administered them to aging animals, the older rats' myelin levels rose by 62 percent, the team reported in February in Glia. © 2014 Scientific American

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 19324 - Posted: 03.05.2014

By GRETCHEN REYNOLDS Obesity may have harmful effects on the brain, and exercise may counteract many of those negative effects, according to sophisticated new neurological experiments with mice, even when the animals do not lose much weight. While it’s impossible to know if human brains respond in precisely the same way to fat and physical activity, the findings offer one more reason to get out and exercise. It’s been known for some time that obesity can alter cognition in animals. Past experiments with lab rodents, for instance, have shown that obese animals display poor memory and learning skills compared to their normal-weight peers. They don’t recognize familiar objects or recall the location of the exit in mazes that they’ve negotiated multiple times. But scientists hadn’t understood how excess weight affects the brain. Fat cells, they knew, manufacture and release substances into the bloodstream that flow to other parts of the body, including the heart and muscles. There, these substances jump-start biochemical processes that produce severe inflammation and other conditions that can lead to poor health. Many thought the brain, though, should be insulated from those harmful effects. It contains no fat cells and sits behind the protective blood-brain barrier that usually blocks the entry of undesirable molecules. However, recent disquieting studies in animals indicate that obesity weakens that barrier, leaving it leaky and permeable. In obese animals, substances released by fat cells can ooze past the barrier and into the brain. The consequences of that seepage became the subject of new neurological experiments conducted by researchers at Georgia Regents University in Augusta and published last month in The Journal of Neuroscience. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19323 - Posted: 03.05.2014

By Deborah Kotz / Globe Staff Obesity rates plummeted among preschool children in the past decade, from nearly 14 percent to just over 8 percent in 2011-12, according to a new federal government analysis that was hailed by one researcher as a “glimmer of hope.” But the campaign to combat the nation’s obesity epidemic has had no success with adults and older children: Americans remain just as overweight as ever, with two out of three adults at an unhealthy weight and more than one out of three obese in 2011-12, the latest years for which statistics were available. The study, published Tuesday in the Journal of the American Medical Association, examined annual government health and nutrition surveys that sampled more than 9,000 Americans of all ages. Despite the gains for toddlers, the study found that overall among children under age 20, 17 percent were at the extreme obese end of the weight spectrum. Nearly one-third of kids remain either overweight or obese—nearly triple the rate of 50 years ago—which pediatricians blame for the sharp rise in type 2 diabetes, high blood pressure, and high cholesterol levels in children. Rates actually increased in one group: Women over age 60 experienced a rise in obesity from just under 32 percent 10 years ago to over 38 percent in 2011-2012. “Obesity rates haven’t changed for most Americans, but there was a glimmer of hope in preschoolers,” said study leader Cynthia Ogden, an epidemiologist at the federal Centers for Disease Control and Prevention’s National Center for Health Statistics. © 2014 Boston Globe Media Partners, LLC

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 19292 - Posted: 02.26.2014