Links for Keyword: Obesity

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.

Links 1 - 20 of 1110

A Possible Weight Loss Strategy: Skip Breakfast Before Exercise

By Gretchen Reynolds Skipping breakfast before exercise might reduce how much we eat during the remainder of the day, according to a small but intriguing new study of fit young men. The study finds that the choice to eat or omit a meal before an early workout could affect our relationship to food for the rest of the day, in complicated and sometimes unexpected ways. Weight management is, of course, one of the great public — and private — health concerns of our time. But the role of exercise in helping people to maintain, lose or, in some instances, add pounds is problematic. Exercise burns calories, but in many past studies, people who begin a new exercise program do not lose as much weight as would be expected, because they often compensate for the energy used during exercise by eating more later or moving less. These compensations, usually subtle and unintended, indicate that our brains are receiving internal communiqués detailing how much energy we used during that last workout and, in response, sending biological signals that increase hunger or reduce our urge to move. Our helpful brains do not wish us to sustain an energy deficit and starve. Previous studies show that many aspects of eating and exercise can affect how much people compensate for the calories burned during exercise, including the type and length of the exercise and the fitness and weight of the exercisers. Skipping or consuming breakfast also can matter. When we eat a meal, our bodies rely on the carbohydrates in those foods as a primary source of energy. Some of those carbohydrates are stored in our bodies, but those internal stores of carbohydrates are small compared to the stores of fat. Some researchers believe that our brains may pay particular attention to any reductions in our carbohydrate levels and rush to replace them. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 26257 - Posted: 05.22.2019

A Daunting Operation Offers Relief to Obese Teenagers

By Gina Kolata At least six million obese teenagers in the United States are candidates for weight-loss surgery, experts estimate. Fewer than 1,000 of them get it each year. Many of these adolescents already have complications of obesity, like diabetes or high blood pressure. But doctors have been uncertain just how well surgery works for young patients, and whether they can handle the consequences, including a severely restricted diet. A new study provides some hopeful answers. Researchers followed 161 teenagers aged 13 to 19, and 396 adults aged 25 to 50, for five years after weight-loss surgery. The teenagers actually fared better than the adults. The adolescents lost at least as much weight, and were more likely to see high blood pressure and diabetes ease or go away, the investigators reported on Wednesday in the New England Journal of Medicine. “This really changes the game,” said Dr. Amir Ghaferi, a bariatric surgeon at the University of Michigan, who was not involved in the research. The paper, he said, added to evidence that obesity, like cancer, is best treated early, before long-term damage from related conditions, such as high blood pressure and diabetes, sets in. To have the surgery, teenagers in the study had to meet the same criteria as adults: a body mass index of at least 35 — for instance, a person who is 5 feet 2 inches tall and weighs 192 pounds or more — and obesity-related health problems. Alternately, the adolescents could have a B.M.I. of at least 40 — such as a person who is 5 feet 2 inches tall and weighs at least 220 pounds — without other conditions linked to obesity. There is no exact data on the number of teenagers who meet those criteria in the United States, said Dr. Thomas Inge, chief of pediatric surgery at Children’s Hospital Colorado and lead author of the new study. © 2019 The New York Times Company

Does eating ultraprocessed food affect weight gain? It’s complicated

Aimee Cunningham Nutrition advice can be confusing. Studies that bolster the health benefits of a food or nutrient seem inevitably to be followed by other work undercutting the good news. One reason for the muddle is that nutrition studies sometimes depend on people’s self-reporting of past meals. And because people may forget or even lie about what they’ve been consuming, that data can be flawed, creating conflicting reports about what’s healthy and what’s not, research has shown. But even if people had a photographic memory of all of their meals, that alone wouldn’t provide enough information. How bodies react to and process food can vary widely from person to person and be dependent on genes, the microbes that live inside the gut, a person’s current health, what the food contains or even how it was made (SN: 1/9/16, p. 8). “The problem is that nutrition research is rocket science,” says David Ludwig, a pediatric endocrinologist at Boston Children’s Hospital. “There are potentially thousands of different nutrients and factors in food that could influence our biology or our senses as we eat. Those can interact in unpredictable and complicated ways.” Given the complexity that comes with researching diet, one approach is to study people in a controlled environment, so that researchers know exactly what the participants are eating. A study that tied eating highly processed foods to weight gain, published online May 16 in Cell Metabolism, did just that. Here’s what the researchers learned — and what they still can’t answer. © Society for Science & the Public 2000 - 2019

How Useful Would A Genetic Test For Obesity Risk Be?

Richard Harris Scientists who recently announced an experimental genetic test that can help predict obesity got immediate pushback from other researchers, who wonder whether it is really useful. The story behind this back-and-forth is, at its core, a question of when it's worth diving deep into DNA databanks when there's no obvious way to put that information into use. The basic facts are not in dispute. Human behavior and our obesity-promoting environment have led to a surge in this condition over the past few decades. Today about 40% of American adults are obese and even more are overweight. But genetics also plays an important role. People inherit genes that make them more or less likely to become seriously overweight. While some diseases (like Huntington's and Tay-Sachs) are caused by a single gene gone awry, that's certainly not the case for common conditions, including obesity. Instead, untold thousands of genes apparently play a role in increasing obesity risk. Many of those gene variants contribute a miniscule risk. Sekar Kathiresan, a cardiologist at Harvard and a geneticist at the Broad Institute, set out to see whether he and his team could find a bunch of these genetic variants and add up their effects. The goal was to identify genetic patterns that put people at the highest risk. This genetic information "could explain why somebody's so big, why they have so much trouble keeping their weight down," Kathiresan says. His team identified more than 2 million DNA variants of potential interest. He figures most of those variants are irrelevant, but his hunch is, hidden somewhere in there are a few thousand changes that each contribute at least a tiny bit to a person's risk of developing obesity. © 2019 npr

This Genetic Mutation Makes People Feel Full — All the Time

By Gina Kolata The study subjects had been thin all their lives, and not because they had unusual metabolisms. They just did not care much about food. They never ate enormous amounts, never obsessed on the next meal. Now, a group of researchers in Britain may have found the reason. The people carry a genetic alteration that mutes appetite. It also greatly reduces their chances of getting diabetes or heart disease. The scientists’ study, published on Thursday in the journal Cell, relied on data from the U.K. Biobank, which includes a half million people aged 40 to 69. Participants have provided DNA samples and medical records, and have allowed researchers to track their health over years. A second study in the same journal also used data from this population to develop a genetic risk score for obesity. It can help predict, as early as childhood, who is at high risk for a lifetime of obesity and who is not. Together, the studies confirm a truth that researchers wish more people understood. There are biological reasons that some struggle mightily with their weight and others do not, and the biological impacts often are seen on appetite, not metabolism. People who gain too much weight or fight to stay thin feel hungrier than naturally thin people. The study of the appetite-dulling mutation was led by Dr. Sadaf Farooqi, professor of metabolism and medicine at the University of Cambridge, and Nick Wareham, an epidemiologist at the university. The study drew on Dr. Farooqi’s research into a gene, MC4R. She has probed it for 20 years, but for the opposite reason: to understand why some people are overweight, not why some are thin. © 2019 The New York Times Company

Related chapters from BN8e: 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: 26156 - Posted: 04.19.2019

A genetic scorecard could predict your risk of being obese

Tina Hesman Saey There’s a new way to predict whether a baby will grow into an obese adult. Combining the effect of more than 2.1 million genetic variants, researchers have created a genetic predisposition score that they say predicts severe obesity. People with scores in the highest 10 percent weighed, on average, 13 kilograms (about 29 pounds) more than those with the lowest 10 percent of scores, the team reports April 18 in Cell. The finding may better quantify genes’ roles in obesity than previous prediction scores, but still fails to account for lifestyle, which may be more important in determining body weight, other researchers say. Still, the study shows that “your genetics really start to take hold very early in life,” says coauthor Amit Khera, a cardiologist at Massachusetts General Hospital and the Broad Institute of MIT and Harvard. Weight differences showed up as early as age 3, and by age 18, those with the highest scores weighed 12.3 kilograms more on average than those with the lowest scores, Khera and his colleagues found. Some people with high genetic scores had normal body weights, but those people may have to work harder to maintain a healthy weight than others, he says. People with the highest scores were 25 times more likely to have severe obesity — a body mass index (BMI) greater than 40 — than those with the lowest scores. BMI is a measurement of body fat based on height and weight. A BMI of 18.5 (calculated as kilograms per meters squared of height) to 24.9 is considered healthy. BMIs 30 and above are considered obese. |© Society for Science & the Public 2000 - 2019

A Heart-Healthy Diet May Be Good for the Brain

By Nicholas Bakalar Eating a heart-healthy diet beginning in your 20s may provide brain benefits in middle age, new research suggests. The study, in Neurology, ranked 2,621 people on their degree of adherence to three different diets considered to be good for the heart. All emphasize vegetables, fruits and whole grains and minimize saturated fat consumption: the Mediterranean diet, which involves mainly plant-based foods and moderate alcohol intake; a research-based diet plan that rates food groups as favorable or not; and the DASH diet, which stresses low-sodium foods. Researchers tracked their diet compliance at ages 25, 32 and 45, and tested mental acuity at 50 and then again at 55. Those who adhered most strictly to the Mediterranean or the food group diet scored higher than those who did not, especially on tests of executive function, which involves organizing and planning. After adjusting for many health and behavioral factors, people with the strictest adherence to these diets had a 46 to 52 percent lower risk of poor cognitive function. But adherence to the DASH diet, which does not consider alcohol consumption, was not associated with cognitive test scores. Which diet is best? “We can say at this point that a heart-healthy diet like the Mediterranean diet is a good option,” said the lead author, Claire T. McEvoy, a dietitian and epidemiologist at Queen’s University Belfast. “It’s palatable and adaptable, and in that respect it’s a pretty good dietary pattern.” © 2019 The New York Times Company

Drug Companies and Doctors Battle Over the Future of Fecal Transplants

By Andrew Jacobs CAMBRIDGE, Mass. — There’s a new war raging in health care, with hundreds of millions of dollars at stake and thousands of lives in the balance. The battle, pitting drug companies against doctors and patient advocates, is being fought over the unlikeliest of substances: human excrement. The clash is over the future of fecal microbiota transplants, or F.M.T., a revolutionary treatment that has proved remarkably effective in treating Clostridioides difficile, a debilitating bacterial infection that strikes 500,000 Americans a year and kills 30,000. The therapy transfers fecal matter from healthy donors into the bowels of ailing patients, restoring the beneficial works of the community of gut microbes that have been decimated by antibiotics. Scientists see potential for using these organisms to treat diseases from diabetes to cancer. At the heart of the controversy is a question of classification: Are the fecal microbiota that cure C. diff a drug, or are they more akin to organs, tissues and blood products that are transferred from the healthy to treat the sick? The answer will determine how the Food and Drug Administration regulates the procedure, how much it costs and who gets to profit. In 2013, the F.D.A. announced a draft decision to regulate the therapy as a new drug but said it would continue to study the matter before reaching a final decision — which is expected to happen soon. Critics say that approach is based on outdated science and could lead to increased costs for patients, most of whom currently rely on a nonprofit stool bank in Cambridge. At stake, some researchers say, is the future of pioneering therapies that harness the human microbiome — the trillions of organisms that colonize the body and are increasingly seen as critical for healthy brain development and immune function. © 2019 The New York Times Company

The Best Type of Exercise to Burn Fat

By Gretchen Reynolds A few minutes of brief, intense exercise may be as effective as much lengthier walks or other moderate workouts for incinerating body fat, according to a helpful new review of the effects of exercise on fat loss. The review finds that super-short intervals could even, in some cases, burn more fat than a long walk or jog, but the effort involved needs to be arduous. I have written many times about the health, fitness and brevity benefits of high-intensity interval training, which typically involves a few minutes — or even seconds — of strenuous exertion followed by a period of rest, with the sequence repeated multiple times. Most H.I.I.T. workouts require less than half an hour, from beginning to end (including a warm-up and cool-down), and the strenuous portions of the workout are even briefer. But despite this concision, studies show that interval workouts can improve aerobic fitness, blood sugar control, blood pressure and other measures of health and fitness to the same or a greater extent than standard endurance training, such as brisk walking or jogging, even if it lasts two or three times as long. People being people, though, the most common question I hear about quickie intervals and have asked, on my own behalf, is whether they also will aid in weight control and fat loss. Only a few past studies have directly compared the fat-burning effects of endurance training to those of short interval workouts, however, and their results have been inconsistent. Some indicate that intervals prompt significant fat loss and others that any losses are negligible when compared to the effects of endurance training.

Think You’ve Gained Weight This Winter? Check Out These Squirrels

By C. Claiborne Ray Q. What keeps squirrels from gaining huge amounts of weight as they gorge on acorns and nuts each fall? A. In fact, many squirrels do achieve huge weight gain ahead of the privations of winter. Common gray squirrels may increase their weight by 25 percent in the harvest season. But not because they hibernate — they don’t. Winter foraging is hard, and gray squirrels tend to spend the winter months mostly in their nests. But they must make forays every few days to seek squirreled-away food and other nourishment. Among hibernating squirrels, much of the stored nourishment is needed to survive the cold season without foraging. A study of the Arctic ground squirrel found extreme weight gains during the active season: 42 percent among males and 63 percent among females. They slow their activity drastically before hibernating in order to maintain peak mass. While some do emerge from winter lighter, a significant share of their fat stores may remain. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 10: Biological Rhythms and Sleep
Link ID: 25952 - Posted: 02.12.2019

Germs in Your Gut Are Talking to Your Brain. Scientists Want to Know What They’re Saying

By Carl Zimmer In 2014 John Cryan, a professor at University College Cork in Ireland, attended a meeting in California about Alzheimer’s disease. He wasn’t an expert on dementia. Instead, he studied the microbiome, the trillions of microbes inside the healthy human body. Dr. Cryan and other scientists were beginning to find hints that these microbes could influence the brain and behavior. Perhaps, he told the scientific gathering, the microbiome has a role in the development of Alzheimer’s disease. The idea was not well received. “I’ve never given a talk to so many people who didn’t believe what I was saying,” Dr. Cryan recalled. A lot has changed since then: Research continues to turn up remarkable links between the microbiome and the brain. Scientists are finding evidence that microbiome may play a role not just in Alzheimer’s disease, but Parkinson’s disease, depression, schizophrenia, autism and other conditions. For some neuroscientists, new studies have changed the way they think about the brain. One of the skeptics at that Alzheimer’s meeting was Sangram Sisodia, a neurobiologist at the University of Chicago. He wasn’t swayed by Dr. Cryan’s talk, but later he decided to put the idea to a simple test. “It was just on a lark,” said Dr. Sisodia. “We had no idea how it would turn out.” He and his colleagues gave antibiotics to mice prone to develop a version of Alzheimer’s disease, in order to kill off much of the gut bacteria in the mice. Later, when the scientists inspected the animals’ brains, they found far fewer of the protein clumps linked to dementia. Just a little disruption of the microbiome was enough to produce this effect. Young mice given antibiotics for a week had fewer clumps in their brains when they grew old, too. © 2019 The New York Times Company

Outrunning Hunger

By Gretchen Reynolds Exercise and eating have a fraught, unsettled relationship with each other. Workouts can blunt or boost appetites. People who start an exercise program often overeat and gain weight — and yet studies and lived experience demonstrate that regular exercise is needed to avoid regaining the weight lost during a successful diet. Intrigued by these contradictory outcomes, researchers at the University of Texas Southwestern Medical Center, along with colleagues from other institutions, ran an experiment on the melanocortin circuit, a brain network in the hypothalamus known to be involved in metabolism. The resulting study, published in December in Molecular Metabolism, suggests that intense exercise might change the workings of certain neurons in ways that could have beneficial effects on appetite and metabolism. The melanocortin circuit consists mainly of two types of neurons. The neuropeptide Y (NPY) cells relay signals encouraging the body to seek food, while the pro-opiomelanocortin (POMC) neurons countermand those orders, reducing interest in food. Animals, including humans, that lack healthy POMC neurons usually become morbidly obese. The researchers focused on what exercise would do to these cells in mice, whose melanocortin circuits resemble ours. Healthy adult male mice either ran on small treadmills or, in a control group, were placed on unmoving treadmills. The exercise routine consisted of 60 minutes of fast, intense running, broken into three 20-minute blocks. Afterward, the mice were free to eat or not, as they chose. The researchers then checked neuronal activity in some of their brains by microscopically probing individual cells in living tissue to measure their electrical and biochemical signals. The tests were repeated throughout the study, which ran for as many as 10 days for some mice. © 2019 The New York Times Company

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 5: The Sensorimotor System
Link ID: 25911 - Posted: 01.29.2019

For Real Weight Control, Try Portion Control

By Jane E. Brody I had hoped to avoid ushering in the new year with yet another weight/diet column, but three circumstances prompted me to reconsider: 1) The latest data released by the Centers for Disease Control and Prevention showed that the weight of American men and women has continued its upward climb, with the average B.M.I. now almost at the cutoff for obesity; 2) The Food and Drug Administration is rolling out changes in serving sizes on packaged foods that could very well make matters worse, especially for consumers of ice cream and soda, and 3) Some good news for a change: the publication of an eminently sensible approach to weight loss, “Finally Full, Finally Slim,” written by a leading expert on portion control, Lisa R. Young, a registered dietitian and adjunct professor of nutrition at New York University. Unlike the myriad diet fads that have yet to stem the ever-increasing girth of American men and women, what Dr. Young describes is not a diet but a practical approach to food and eating that can be adapted to almost any way of life, even if most meals are eaten out or taken out. It is not prescriptive or even proscriptive. It does not cut out any category of food, like carbohydrates or fats, nor does it deprive people of their favorite foods, including sweet treats. And it works. I know, because more than half a century ago I lost 40 pounds in two years following Dr. Young’s approach, and I’ve kept the weight off ever since without dieting or deprivation. It fills me up with delicious, nutritious foods and allows me to enjoy a frequent nightcap of ice cream — half a cup (measured) at 150 calories or less. © 2019 The New York Times Company

Skinny genes the 'secret to staying slim'

By Smitha Mundasad Global Health Correspondent, BBC News Scientists say they have discovered the secret behind why some people are skinny while others pile on the pounds easily. Their work reveals newly discovered genetic regions linked to being very slim. The international team say this supports the idea that, for some people, being thin has more to do with inheriting a "lucky" set of genes than having a perfect diet or lifestyle. The study appears in PLOS Genetics. In the past few decades, researchers have found hundreds of genetic changes that increase the chance of a person being overweight - but there has been much less focus on the genes of people who are thin. In this investigation, scientists compared DNA samples from 1,600 healthy thin people in the UK - with a body mass index (BMI) of less than 18 - with those of 2,000 severely obese people and 10,400 people of normal weight. They also looked closely at lifestyle questionnaires - to rule out eating disorders, for example. Researchers found people who were obese were more likely to have a set of genes linked to being overweight. Meanwhile, people who were skinny not only had fewer genes linked to obesity but also had changes in gene regions newly associated with healthy thinness. Lead researcher Prof Sadaf Farooqi, from the University of Cambridge, called on people to be less judgemental about others' weight. "This research shows for the first time that healthy thin people are generally thin because they have a lower burden of genes that increase a person's chances of being overweight and not because they are morally superior, as some people like to suggest," she said. © 2019 BBC.

Memories of eating influence your next meal – new research pinpoints brain cells involved

Marise Parent Of course you know that eating is vital to your survival, but have you ever thought about how your brain controls how much you eat, when you eat and what you eat? This is not a trivial question, because two-thirds of Americans are either overweight or obese and overeating is a major cause of this epidemic. To date, the scientific effort to understand how the brain controls eating has focused primarily on brain areas involved in hunger, fullness and pleasure. To be better armed in the fight against obesity, neuroscientists, including me, are starting to expand our investigation to other parts of the brain associated with different functions. My lab’s recent research focuses on one that’s been relatively overlooked: memory. For many people, decisions about whether to eat now, what to eat and how much to eat are often influenced by memories of what they ate recently. For instance, in addition to my scale and tight clothes, my memory of overeating pizza yesterday played a pivotal role in my decision to eat salad for lunch today. Memories of recently eaten foods can serve as a powerful mechanism for controlling eating behavior because they provide you with a record of your recent intake that likely outlasts most of the hormonal and brain signals generated by your meal. But surprisingly, the brain regions that allow memory to control future eating behavior are largely unknown. Studies done in people support the idea that meal-related memory can control future eating behavior. © 2010–2019, The Conversation US, Inc.

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory, Learning, and Development
Link ID: 25866 - Posted: 01.15.2019

Doubts Raised About Brain Stimulation to Reduce Food Cravings

Abby Olena In the never-ending search for ways to help people eat healthy, scientists have been looking into brain stimulation, specifically, sending a weak electrical current to the brain through two scalp electrodes—a technique called transcranial direct current stimulation. It has previously shown promise in limiting both food cravings and consumption in people, but in a study published yesterday (January 9) in Royal Society Open Science, researchers didn’t find any effects of tDCS on food-related behavior, indicating that the technique’s use needs another look. “The good things about the study are the large sample size and the fact that it’s fairly rigorous,” says Mark George, a psychiatrist and neurologist at the Medical University of South Carolina who did not participate in the study. “The problem [is] interpreting studies where there’s a failure to find. All you can say is that it didn’t work . . . with this group.” During tDCS, one to two milliamps of electricity—enough to feel tingles or pins and needles, but far less than the 800 or so milliamps used for electroconvulsive therapy—are delivered to the brain. Over the last two decades, scientists have reported targeting the technique to the dorsolateral prefrontal cortex, a brain area that’s been shown to be involved in food-related behavior. They’ve found it has helped people crave less and, to a lesser extent, eat fewer sweets and other tempting foods. Yet these experiments have generally included groups of 20 or fewer people, and other studies have failed to replicate their effects. © 1986 - 2019 The Scientist.

Tiny implantable wireless devices could help people repair nerves and lose weight

By Robert F. Service BOSTON—Implanted electronics can steady hearts, calm tremors, and heal wounds—but at a cost. These machines are often large, obtrusive contraptions with batteries and wires, which require surgery to implant and sometimes need replacement. That's changing. At a meeting of the Materials Research Society here last month, biomedical engineers unveiled bioelectronics that can do more in less space, require no batteries, and can even dissolve when no longer needed. "Huge leaps in technology [are] being made in this field," says Shervanthi Homer-Vanniasinkam, a biomedical engineer at University College London. By making bioelectronics easier to live with, these advances could expand their use. "If you can tap into this, you can bring a new approach to medicine beyond pharmaceuticals," says Bernhard Wolfrum, a neuroelectronics expert at the Technical University of Munich in Germany. "There are a lot of people moving in this direction." One is John Rogers, a materials scientist at Northwestern University in Evanston, Illinois, who is trying to improve on an existing device that surgeons use to stimulate healing of damaged peripheral nerves in trauma patients. During surgery, doctors suture severed nerves back together and then provide gentle electrical stimulation by placing electrodes on either side of the repair. But because surgeons close wounds as soon as possible to prevent infection, they typically provide this stimulation for an hour or less. © 2018 American Association for the Advancement of Science

What We Know About Diet and Weight Loss

By Gina Kolata You’d think that scientists at an international conference on obesity would know by now which diet is best, and why. As it turns out, even the experts still have widely divergent opinions. At a recent meeting of the Obesity Society, organizers held a symposium during which two leading scientists presented the somewhat contradictory findings of two high-profile diet studies. A moderator tried to sort things out. In one study, by Christopher Gardner, a professor of medicine at Stanford, patients were given low-fat or low-carb diets with the same amount of calories. After a year, weight loss was the same in each group, Dr. Gardner reported. Another study, by Dr. David Ludwig of Boston Children’s Hospital, reported that a low-carbohydrate diet was better than a high-carbohydrate diet in helping subjects keep weight off after they had dieted and lost. The low-carbohydrate diet, he found, enabled participants to burn about 200 extra calories a day. So does a low-carbohydrate diet help people burn more calories? Or is the composition of the diet irrelevant if the calories are the same? Does it matter if the question is how to lose weight or how to keep it off? There was no consensus at the end of the session. But here are a few certainties about dieting amid the sea of unknowns. What we know People vary — a lot — in how they respond to dieting. Some people thrive on low-fat diets, others do best on low-carb diets. Still others succeed with gluten-free diets or Paleo diets or periodic fasts or ketogenic diets or other options on the seemingly endless menu of weight-loss plans. Most studies comparing diets have produced results like Dr. Gardner’s: no difference © 2018 The New York Times Company

A New Connection between the Gut and the Brain

By Jonathan D. Grinstein It is well known that a high salt diet leads to high blood pressure, a risk factor for an array of health problems, including heart disease and stroke. But over the last decade, studies across human populations have reported the association between salt intake and stroke irrespective of high blood pressure and risk of heart disease, suggesting a missing link between salt intake and brain health. Interestingly, there is a growing body of work showing that there is communication between the gut and brain, now commonly dubbed the gut–brain axis. The disruption of the gut–brain axis contributes to a diverse range of diseases, including Parkinson’s disease and irritable bowel syndrome. Consequently, the developing field of gut–brain axis research is rapidly growing and evolving. Five years ago, a couple of studies showed that high salt intake leads to profound immune changes in the gut, resulting in increased vulnerability of the brain to autoimmunity—when the immune system attacks its own healthy cells and tissues by mistake, suggesting that perhaps the gut can communicate with the brain via immune signaling. Now, new research shows another connection: immune signals sent from the gut can compromise the brain’s blood vessels, leading to deteriorated brain heath and cognitive impairment. Surprisingly, the research unveils a previously undescribed gut–brain connection mediated by the immune system and indicates that excessive salt might negatively impact brain health in humans through impairing the brain’s blood vessels regardless of its effect on blood pressure. © 2018 Scientific American

Related chapters from BN8e: 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: 25754 - Posted: 12.06.2018

Limited Meal Times Prevent Obesity in Mice Prone to Gaining Weight

Abby Olena Mice with faulty circadian clocks are prone to obesity and diabetes. So are mice fed a diet high in fat. Remarkably, animals that have both of these obesity-driving conditions can stay lean and metabolically healthy by simply limiting the time of day when they eat. In a study published today (August 30) in Cell Metabolism, researchers report that restricting feeding times to mice’s active hours can overcome both defective clock genes and an unhealthy diet, a finding that may have an impact in the clinic. The work corroborates previous research showing how powerful restricted feeding can be to improve clock function, says Kristin Eckel-Mahan, a circadian biologist at the University of Texas Health Science Center at Houston who did not participate in the study. Over the last 20 years, biologists have found circadian clocks keeping physiologic time in almost every organ. They have also shown that mice with disrupted clocks often develop metabolic diseases, such as obesity, and that circadian clock proteins physically bind to the promoters of many metabolic regulators and instruct them when to turn on and off. For Satchidananda Panda of the Salk Institute, these lines of evidence came together in 2009, when his group published a study showing that in mice without the clock component Cryptochrome, feeding and fasting could drive the expression of some, but not all, of the metabolic regulators throughout the body. Other groups have also confirmed that even in the absence of the clock it is still possible to drive some genetic rhythms. In this latest study, he and colleagues wanted to look more closely at how the cycling of clock and metabolic transcripts induced by time-restricted feeding, rather than normal genetic rhythms, influences the health of mice. © 1986 - 2018 The Scientist

Links By Chapter:

Links for Keyword: Obesity