Chapter 13. Homeostasis: Active Regulation of the Internal Environment

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

Links 1 - 20 of 1892

Allison Whitten When our phones and computers run out of power, their glowing screens go dark and they die a sort of digital death. But switch them to low-power mode to conserve energy, and they cut expendable operations to keep basic processes humming along until their batteries can be recharged. Our energy-intensive brain needs to keep its lights on too. Brain cells depend primarily on steady deliveries of the sugar glucose, which they convert to adenosine triphosphate (ATP) to fuel their information processing. When we’re a little hungry, our brain usually doesn’t change its energy consumption much. But given that humans and other animals have historically faced the threat of long periods of starvation, sometimes seasonally, scientists have wondered whether brains might have their own kind of low-power mode for emergencies. Now, in a paper published in Neuron in January, neuroscientists in Nathalie Rochefort’s lab at the University of Edinburgh have revealed an energy-saving strategy in the visual systems of mice. They found that when mice were deprived of sufficient food for weeks at a time — long enough for them to lose 15%-20% of their typical healthy weight — neurons in the visual cortex reduced the amount of ATP used at their synapses by a sizable 29%. But the new mode of processing came with a cost to perception: It impaired how the mice saw details of the world. Because the neurons in low-power mode processed visual signals less precisely, the food-restricted mice performed worse on a challenging visual task. “What you’re getting in this low-power mode is more of a low-resolution image of the world,” said Zahid Padamsey, the first author of the new study. All Rights Reserved © 2022

Keyword: Vision
Link ID: 28376 - Posted: 06.15.2022

By Gina Kolata Maya Cohen’s entree into the world of obesity medicine came as a shock. In despair over her weight, she saw Dr. Caroline Apovian, an obesity specialist at Brigham and Women’s Hospital, who prescribed Saxenda, a recently approved weight-loss drug. Ms. Cohen, who is 55 and lives in Cape Elizabeth, Maine, hastened to get it filled. Then she saw the price her pharmacy was charging: $1,500 a month. Her insurer classified it as a “vanity drug” and would not cover it. “I’m being treated for obesity,” she complained to her insurer, but to no avail. While Ms. Cohen was stunned by her insurer’s denial, Dr. Apovian was not. She says it is an all too common response from insurers when she prescribes weight-loss drugs and the universal response from Medicare drug plans. Obesity specialists despair but hope that with the advent of highly effective drugs, the situation will change. Novo-Nordisk, the maker of the medicine Dr. Apovian prescribed, and patient advocacy groups have been aggressively lobbying insurers to pay for weight-loss drugs. They also have been lobbying Congress to pass a bill that has languished through three administrations that would require Medicare to pay for the drugs. But for now, the status quo has not budged. No one disputes the problem — more than 40 percent of Americans have obesity, and most have tried repeatedly to lose weight and keep it off, only to fail. Many suffer from medical conditions that are linked to obesity, including diabetes, joint and back pain and heart disease, and those conditions often improve with weight loss. © 2022 The New York Times Company

Keyword: Obesity
Link ID: 28342 - Posted: 06.01.2022

By Gina Kolata An experimental drug has enabled people with obesity or who are overweight to lose about 22.5 percent of their body weight, about 52 pounds on average, in a large trial, the drug’s maker announced on Thursday. The company, Eli Lilly, has not yet submitted the data for publication in a peer-reviewed medical journal or presented them in a public setting. But the claims nonetheless amazed medical experts. “Wow (and a double Wow!)” Dr. Sekar Kathiresan, chief executive of Verve Therapeutics, a company focusing on heart disease drugs, wrote in a tweet. Drugs like Eli Lilly’s, he added, are “truly going to revolutionize the treatment of obesity!!!” Dr. Kathiresan has no ties to Eli Lilly or to the drug. Dr. Lee Kaplan, an obesity expert at the Massachusetts General Hospital, said that the drug’s effect “appears to be significantly better than any other anti-obesity medication that is currently available in the U.S.” The results, he added, are “very impressive.” Dr. Kaplan who consults for a dozen pharmaceutical companies, including Eli Lilly, said he was not involved in the new trial or in the development of this drug. On average, participants in the study weighed 231 pounds at the outset and had a body mass index, or B.M.I. — a commonly used measure of obesity — of 38. (Obesity is defined as a B.M.I. of 30 and higher. At the end of the study, those taking the higher doses of the Eli Lilly drug, called tirzepatide, weighed about 180 pounds and had a B.M.I. just below 30, on average. The results far exceed those usually seen in trials of weight-loss medications and are usually seen only in surgical patients. Some trial participants lost enough weight to fall into the normal range, said Dr. Louis J. Aronne, director of the comprehensive weight control program at Weill Cornell Medical Center, who worked with Eli Lilly as the study’s principal investigator. Most of the people in the trial did not qualify for bariatric surgery, which is reserved for people with a B.M.I. over 40, or those with a B.M.I. from 35 to 40 with sleep apnea or Type 2 diabetes. The risk of developing diabetes is many times higher for people with obesity than for people without it. © 2022 The New York Times Company

Keyword: Obesity
Link ID: 28311 - Posted: 04.30.2022

pmByElizabeth Pennisi With more microbes than cells in our body, it’s not surprising that bacteria and other invisible “guests” influence our metabolism, immune system, and even our behavior. Now, researchers studying mice have worked out how bacteria in the mammalian gut can ping the brain to regulate an animal’s appetite and body temperature—and it involves the same molecular pathway the immune system uses to detect bacterial pathogens. “It’s quite an important finding,” says Antoine Adamantidis, a neuroscientist at the University of Bern who was not involved with the work. “Our life depends on food intake, and this is one more [thing] that bacteria can [influence].” Over the past 20 years, researchers have uncovered connections between the human gut and the rest of the body. They have linked certain intestinal microbes to conditions such as depression, multiple sclerosis, and immune system disorders; they have also documented nervous system connections between the gut and the brain. But researchers have been hard pressed to understand exactly how gut microbes—or the molecules they make—influence the brain. When certain gut bacteria infiltrate the rest of the body, our immune system picks up on them by sensing fragments of their cell walls, known as muropeptides. Our molecular detectors for these muropeptides, proteins called Nod2, coat the surfaces of cells involved in the body’s first line of defense. Ilana Gabanyi, a neuroimmunologist at the Pasteur Institute, wanted to know whether these molecular detectors also exist in the brain’s nerve cells. © 2022 American Association for the Advancement of Science.

Keyword: Obesity
Link ID: 28293 - Posted: 04.20.2022

Linda Geddes Setting daily meat reduction goals and keeping an online diary of intake helped frequent meat eaters to halve their consumption in just over nine weeks, a trial has found. The trial, by researchers at the University of Oxford’s Livestock, Environment and People (Leap) programme, also found the routine was popular with participants, who felt it supported them to change their diet. Many people wish to reduce their meat consumption, whether for health or environmental reasons, or animal welfare concerns. Leap researchers wondered whether tapping into psychological principles employed by weight-loss apps, such as Noom, could help boost participants’ resolve. They developed an online platform called the Optimise meat tracker (standing for online programme to tackle individuals’ meat intake through self-regulation). Users log on and pick one meat reduction strategy from a list to focus on for that day, such as “try a new vegetarian recipe”, or “eat no processed meat”. The next morning they report whether they achieved this and record how much fish, poultry, red and processed meat they consumed. They receive weekly feedback on how they have done. The approach is based on self-regulation theory: the idea that people monitor and contextualise their own behaviour, reflect on it in relation to their goals, and try to modify it in response to feedback. “We know that people tend to underestimate the amount of meat they eat, the health and environmental impacts of their meat consumption; we also know that our meat-eating habits are strongly engrained. This process of self-regulation tries to tap into all of that,” said Dr Cristina Stewart at the University of Oxford, who led the research. © 2022 Guardian News & Media Limited

Keyword: Obesity
Link ID: 28231 - Posted: 03.05.2022

By Diana Kwon People with a rare genetic disorder known as Prader-Willi syndrome never feel full, and this insatiable hunger can lead to life-threatening obesity. Scientists studying the problem have now found that the fist-shaped structure known as the cerebellum—which had not previously been linked to hunger—is key to regulating satiation in those with this condition. This finding is the latest in a series of discoveries revealing that the cerebellum, long thought to be primarily involved in motor coordination, also plays a broad role in cognition, emotion and behavior. “We’ve opened up a whole field of cerebellar control of food intake,” says Albert Chen, a neuroscientist at the Scintillon Institute in California. The project began with a serendipitous observation: Chen and his team noticed they could make mice stop eating by activating small pockets of neurons in regions known as the anterior deep cerebellar nuclei (aDCN), within the cerebellum. Intrigued, the researchers contacted collaborators at Harvard Medical School. Scientists there had gathered data using functional MRI to compare brain activity in 14 people who had Prader-Willi syndrome with activity in 14 unaffected people while each subject viewed images of food—either immediately following a meal or after fasting for at least four hours. New analysis of these scans revealed that activity in the same regions Chen’s group had pinpointed in mice, the aDCN, appeared to be significantly disrupted in humans with Prader-Willi syndrome. In healthy individuals, the aDCN were more active in response to food images while fasting than just after a meal, but no such difference was identifiable in participants with the disorder. The result suggested that the aDCN were involved in controlling hunger. Further experiments on mice, conducted by researchers from several different institutions, demonstrated that activating the animals’ aDCN neurons dramatically reduced food intake by blunting how the brain’s pleasure center responds to food. The findings were recently detailed in Nature. © 2022 Scientific American,

Keyword: Obesity
Link ID: 28219 - Posted: 02.26.2022

By Matt Richtel During the pandemic, emergency rooms across the country reported an increase in visits from teenage girls dealing with eating and other disorders, including anxiety, depression and stress, according to new data from the Centers for Disease Control and Prevention. The report provides new detail about the kinds of mental health issues affecting a generation of adolescents. Mental health experts hypothesize that the pandemic prompted some youth to feel isolated, lonely and out-of-control. Some coped by seeking to have control over their own behavior, said Emily Pluhar, a pediatric psychologist at Boston Children’s Hospital and instructor at Harvard Medical School. “You take a very vulnerable group and put on a global pandemic,” she said. “The eating disorders are out of control.” In the C.D.C. study, the agency said that the proportion of eating disorder visits doubled among teenage girls, set off by pandemic-related risk factors, like the “lack of structure in daily routine, emotional distress and changes in food availability.” The agency said that the increase in tic disorders was “atypical,” as these disorders often present earlier, and are more common in boys. But the C.D.C., reinforcing speculation from other clinicians and researchers, said that some teenage girls may be developing tics after seeing the phenomenon spread widely on social media, notably on TikTok. “Stress of the pandemic or exposure to severe tics, highlighted on social media platforms, might be associated with increases in visits with tics and tic-like behavior among adolescent females,” the C.D.C. wrote. In a related report, the C.D.C. also said on Friday that the increase in visits for mental health issues occurred as emergency rooms reported sharp declines overall in visits during the pandemic. As compared with 2019, overall visits fell by 51 percent in 2020 and by 22 percent in 2021, declines that the agency attributed in part to families delaying care, and a drop in physical injuries from activities like swimming and running. © 2022 The New York Times Company

Keyword: Anorexia & Bulimia; Stress
Link ID: 28213 - Posted: 02.19.2022

by Angie Voyles Askham Mice chemically coaxed to produce high levels of an autism-linked gut molecule have anxiety-like behavior and unusual patterns of brain connectivity, according to a study published today in Nature. The findings present a direct mechanism by which the gut could send signals to the brain and alter development, the researchers say. “It’s a true mechanistic paper, [like] the field has been asking for,” says Jane Foster, professor of psychiatry and behavioral neurosciences at McMaster University in Hamilton, Canada, who was not involved in the study. Although it’s not clear that this exact signaling pathway is happening in people, she says, “this is the sort of work that’s going to get us that answer.” The molecule, 4-ethylphenol (4EP), is produced by gut microbes in mice and people. An enzyme in the colon and liver converts 4EP to 4-ethylphenyl sulfate (4EPS), which then circulates in the blood. Mice exposed to a maternal immune response in the womb have atypically high blood levels of 4EPS, as do some autistic people, previous research shows. And injecting mice with the molecule increases behaviors indicative of anxiety. But it wasn’t clear how the molecule could contribute to those traits. In the new work, researchers show that 4EPS can enter the brain and that its presence is associated with altered brain connectivity and a decrease in myelin — the insulation around axons that helps conduct electrical signals. Boosting the function of myelin-producing cells, the team found, eases the animals’ anxiety. “This is one of the first — maybe, arguably, the first — demonstrations of a specific microbe molecule that has such a profound impact on a complex behavior,” says lead researcher Sarkis Mazmanian, professor of microbiology at the California Institute of Technology in Pasadena. “How it’s doing it, we still need to understand.” without the engineered enzymes, they showed increased anxiety-like behaviors, © 2022 Simons Foundation

Keyword: Development of the Brain; Neuroimmunology
Link ID: 28205 - Posted: 02.16.2022

Ian Sample Science editor Getting an hour or so more sleep each night can help people to cut calories, according a small clinical trial in overweight adults. Researchers in the US found that people who typically slept for less than 6.5 hours a night shed an average of 270 calories from their daily intake when they got an extra 1.2 hours of sleep. Sustained over three years, the reduction in calories could lead people to lose about 12kg (26lbs) without changing their diet during the day, the scientists believe. Some participants in the study consumed 500 fewer calories a day after improving their sleep. The study was not designed to look at weight loss, but researchers noticed the fall in calories within two weeks of patients changing their sleep patterns. “If healthy sleep habits are maintained over longer duration, this would lead to clinically important weight loss over time,” said Dr Esra Tasali, of the University of Chicago’s sleep centre. “Many people are working hard to find ways to decrease their caloric intake to lose weight – well, just by sleeping more, you may be able to reduce it substantially.” The trial studied 80 adults aged 21 to 40 with a body mass index between 25 and 29.9, meaning they were overweight. Half of the participants were randomly assigned to receive personalised sleep hygiene counselling aimed at extending the amount of time they slept each night. © 2022 Guardian News & Media Limited

Keyword: Sleep; Obesity
Link ID: 28191 - Posted: 02.09.2022

ByElizabeth Pennisi The trillions of bacteria in and on our bodies can bolster our health and contribute to disease, but just which microbes are the key actors has been elusive. Now, a study involving thousands of people in Finland has identified a potential microbial culprit in some cases of depression. The finding, which emerged from a study of how genetics and diet affect the microbiome, “is really solid proof that this association could have major clinical importance,” says Jack Gilbert, a microbial ecologist at the University of California, San Diego, who was not involved with the work. Researchers are finding ever more links between brain conditions and gut microbes. People with autism and mood disorders, for example, have deficits of certain key bacteria in their guts. Whether those microbial deficits actually help cause the disorders is unclear, but the findings have spawned a rush to harness gut microbes and the substances they produce as possible treatments for a variety of brain disorders. Indeed, researchers recently reported in Frontiers in Psychiatry that fecal transplants improved symptoms in two depressed patients. Guillaume Méric didn’t set out to find microbes that cause depression. A microbial bioinformatician at the Baker Heart & Diabetes Institute, he and his colleagues were analyzing data from a large health and lifestyle study from Finland. Part of a 40-year effort to track down underlying causes of chronic disease in Finnish people, the 2002 study assessed the genetic makeup of 6000 participants, identified their gut microbes, and compiled extensive data about their diets, lifestyles, prescription drug use, and health. Researchers tracked the health of participants until 2018. Méric and his colleagues combed the data for clues to how a person’s diet and genetics affect the microbiome. “There have been very few studies that have examined [all these factors] in such detail,” Gilbert says. Two sections of the human genome seemed to strongly influence which microbes are present in the gut, the researchers report this week in Nature Genetics. One contains the gene for digesting the milk sugar lactose, and the other helps specify blood type. (A second study, also published today in Nature Genetics, identified the same genetic loci by analyzing the relationship between the genomes and gut microbes of 7700 people in the Netherlands.) © 2022 American Association for the Advancement of Science.

Keyword: Depression; Obesity
Link ID: 28188 - Posted: 02.05.2022

By Veronique Greenwood Few pleasures compare to a long cool drink on a hot day. As a glass of water or other tasty drink makes its way to your digestive tract, your brain is tracking it — but how? Scientists have known for some time that thirst is controlled by neurons that send an alert to put down the glass when the right amount has been guzzled. What precisely tells them that it is time, though, is still a bit mysterious. In an earlier study, a team of researchers found that the act of gulping a liquid — really anything from water to oil — is enough to trigger a temporary shutdown of thirst. But they knew that gulping was not the only source of satisfaction. There were signals that shut down thirst coming from deeper within the body. In a paper published Wednesday in Nature, scientists from the same lab report that they’ve followed the signals down the neck, through one of the body’s most important nerves, into the gut, and finally to an unexpected place for this trigger: a set of small veins in the liver. The motion of gulping might provide a quick way for the body to monitor fluid intake. But whatever you swallowed will swiftly arrive in the stomach and gut, and then its identity will become clear to your body as something that can fulfill the body’s need for hydration, or not. Water changes the concentration of nutrients in your blood, and researchers believe that this is the trigger for real satiation. “There is a mechanism to ensure that what you’re drinking is water, not anything else,” said Yuki Oka, a professor at Caltech and an author of both studies. To find out where the body senses changes to your blood’s concentration, Dr. Oka and his colleagues first ran water into the intestines of mice and watched the behavior of nerves that connect the brain to the gut area, which are believed to work similarly in humans. One major nerve, the vagus nerve, fired the closest in time with the water’s arrival in the intestines, suggesting that this is the route the information takes on the way to the brain. © 2022 The New York Times Company

Keyword: Obesity
Link ID: 28178 - Posted: 01.29.2022

Hannah V. Carey Matthew Regan Ground squirrels spend the end of summer gorging on food, preparing for hibernation. They need to store a lot of energy as fat, which becomes their primary fuel source underground in their hibernation burrows all winter long. While hibernating, ground squirrels enter a state called torpor. Their metabolism drops to as low as just 1% of summer levels and their body temperature can plummet to close to freezing. Torpor greatly reduces how much energy the animal needs to stay alive until springtime. That long fast comes with a downside: no new input of protein, which is crucial to maintain the body’s tissues and organs. This is a particular problem for muscles. In people, long periods of inactivity, like prolonged bed rest, lead to muscle wasting. But muscle wasting is minimal in hibernating animals. Despite as much as six to nine months of inactivity and no protein intake, they preserve muscle mass and performance remarkably well – a very handy adaptation that helps ensure a successful breeding season come spring. How do hibernators pull this off? It’s been a real head-scratcher for hibernation biologists for decades. Our research team tackled this question by investigating how hibernating animals might be getting a major assist from the microbes that live in their guts. We knew from previous research that a hibernator’s gastrointestinal system undergoes dramatic changes in its structure and function from summer feeding to winter fasting. And it’s not only the animals who are fasting all winter long – their gut microbes are, too. Along with our microbiology collaborators, we figured out that winter fasting changes the gut microbiome quite a bit. © 2010–2022, The Conversation US, Inc.

Keyword: Obesity
Link ID: 28176 - Posted: 01.29.2022

Chloe Tenn Humans have a sugar sense. Animals and humans prefer sugar over artificial sweeteners in experiments, and that could be because a specific gut sensor cell triggers one of two separate neural pathways depending on which it detects, researchers suggest in a January 13 study in Nature Neuroscience. “It has been known for decades that animals prefer sugar to non-caloric sweeteners and that this preference relies on feedback from the gut,” Lisa Beutler, a Northwestern University endocrinologist who researches the connection between the gut and brain and was not affiliated with the new work, writes in an email to The Scientist. “This study is among the first to provide insight at the molecular level into how the gut knows the difference between sugar and non-caloric sweeteners, and how this drives preference.” The study builds on previous research from the lab of Duke University gut-brain neuroscientist Diego Bohórquez. In 2015, Bohórquez established that endocrine cells, which were previously thought to only communicate with the nervous system indirectly through hormone secretion, can in fact have direct contact with neurons, evidenced by a video. Then, in 2018, the Bohórquez Lab found that the gut has similar cells to those that allow for taste on the tongue and smell in the nose, and that these sensors also have direct contact with neurons. “If they are connected to neurons, they must be connected to the brain,” Bohórquez tells The Scientist. “When we ingest sugar, it stimulates cells in the gut, and these cells release glutamate and activate the vagus nerve,” Bohórquez explains of his prior research. The vagus nerve is a cranial nerve that plays a regulatory role in internal organ functions such as digestion. His team observed that these gut sensor cells, which the team dubbed “neuropods,” transmit the chemosensory information mere milliseconds after detecting sugar. © 1986–2022 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Obesity
Link ID: 28170 - Posted: 01.26.2022

ByMichael Price When it comes to killing and eating other creatures, chimpanzees—our closest relatives—have nothing on us. Animal flesh makes up much more of the average human’s diet than a chimp’s. Many scientists have long suggested our blood lust ramped up about 2 million years ago, based on the number of butchery marks found at ancient archaeological sites. The spike in calories from meat, the story goes, allowed one of our early ancestors, Homo erectus, to grow bigger bodies and brains. But a new study argues the evidence behind this hypothesis is statistically flawed because it fails to account for the fact that researchers have focused most of their time and attention on later sites. As a result of this unequal “sampling effort” over time at different sites, the authors say, it’s impossible to know how big a role meat eating played in human evolution. Even before the study, many experts suspected the link between carnivory and bigger brains and bodies in early humans might be complex, says Rachel Carmody, an evolutionary biologist at Harvard University who wasn’t involved in the work. The new results, though, “take the important step of demonstrating empirically that controlling for sampling effort actually changes the interpretation.” To conduct the study, W. Andrew Barr, a paleoanthropologist at George Washington University, and colleagues reviewed previously reported data on the appearance of butchery marks at nine archaeological hotbeds of early human activity across eastern Africa spanning 2.6 million to 1.2 million years ago. As expected, the scientist found an increase in the number of cutmarks on animal bones beginning about 2 million years ago. However, the researchers noticed that archaeologists tended to find more cutmarks at the sites that have received the most research attention. In other words, the more time and effort researchers poured into a site, the more likely they were to discover evidence of meat eating. © 2022 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 28169 - Posted: 01.26.2022

Sophie Fessl Mice raised in an enriched environment are better able to adapt and change than mice raised in standard cages, but why they show this higher brain plasticity has not been known. Now, a study published January 11 in Cell Reports finds that the environment could act indirectly: living in enriched environments changes the animals’ gut microbiota, which appears to modulate plasticity. The study “provides very interesting new insights into possible beneficial effects of environmental enrichment on the brain that might act via the gut,” writes Anthony Hannan, a neuroscientist at the Florey Institute of Neuroscience and Mental Health in Australia who was not involved in the study, in an email to The Scientist. “This new study has implications for how we might understand the beneficial effects of environmental enrichment, and its relevance to cognitive training and physical activity interventions in humans.” In previous studies, mice raised in what scientists call an enriched environment—one in which they have more opportunities to explore, interact with others, and receive sensory stimulation than they would in standard laboratory enclosures—have been better able to modify their neuronal circuits in response to external stimuli than mice raised in smaller, plainer cages. Paola Tognini, a neuroscientist at the University of Pisa and lead author of the new study, writes in an email to The Scientist that she “wondered if endogenous factors (signals coming from inside our body instead of the external world), such as the signals coming from the intestine, could also influence brain plasticity.” © 1986–2022 The Scientist.

Keyword: Learning & Memory; Obesity
Link ID: 28159 - Posted: 01.19.2022

By Tina Hesman Saey Nola Sullivan recently marked an inauspicious anniversary. A little more than a year ago, on November 16, 2020, the 57-year-old pharmacy technician from Kellogg, Idaho, came down with COVID-19. “I lost my taste and smell, with a very bad head cold, body aches, muscle spasm, fatigue, nausea, vomiting, diarrhea,” she says. It took a month for her muscle spasms and a lingering headache to go away. She missed nearly three months of work. Her senses of smell and taste still haven’t fully returned. And “I still have the fatigue. It’s horrible. I’m nauseous all the time.” Sullivan has another lasting reminder of her battle with the coronavirus, too: diabetes. When she finally returned to work at the pharmacy, “I noticed that I was so thirsty all the time. And I just thought that was part of the COVID,” she says. “I was drinking gallons of water.” As a pharmacy technician, though, she knew that excessive thirst can be sign of diabetes. So she decided to check her blood sugar. A person is considered diabetic when levels of glucose in their blood reach 200 milligrams of glucose per deciliter of blood. Sullivan’s was over 500. Sullivan is not alone. In a study of more than 3,800 COVID-19 patients, just under half developed high blood sugar levels, including many, like Sullivan, who were not previously diabetic, cardiologist James Lo and colleagues reported November 2 in Cell Metabolism. About 91 percent of the intubated COVID-19 patients had high blood sugar, as did almost 73 percent of people who died of the disease, the researchers reported. © Society for Science & the Public 2000–2022

Keyword: Obesity
Link ID: 28137 - Posted: 01.05.2022

By Gretchen Reynolds Many of us remember “The Biggest Loser,” the somewhat notorious reality television show that ran for more than a decade starting in 2004, in which contestants competed feverishly to drop massive amounts of weight over a short period of time. One of the biggest lessons of the show appeared to be that extreme exercise, along with draconian calorie restriction, would lead to enormous weight loss. Media coverage of the contestants years later, though, seemed to tell a different story, of weight regain and slowed metabolisms and the futility of attempting long-term weight loss. Now a new scientific analysis of the show and its aftermath, published last month in the journal Obesity, suggests many beliefs about “The Biggest Loser” may be misconceptions. The analysis tries to untangle what really happened to the contestants’ metabolisms and why some of them kept off weight better than others. It also looks into the complex role of exercise and whether staying physically active helped the contestants keep their weight under control for years, or not. For those who may have forgotten, or tried to, “The Biggest Loser” ran on NBC to generally high ratings for more than a dozen seasons. Contestants competed to drop the most pounds using extreme calorie restriction and hours of daily strenuous exercise. “Winners” typically shed hundreds of pounds in a few months. Such rapid and extreme weight loss caught the attention of Kevin Hall, a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases, which is part of the National Institutes of Health. An expert on metabolism, Dr. Hall knew that when people drop lots of weight in a short period of time, they typically send their resting metabolic rates — the baseline calories we burn every day just by being alive — into free-fall. A lower resting metabolic rate can mean we burn fewer calories over all. © 2021 The New York Times Company

Keyword: Obesity
Link ID: 28110 - Posted: 12.15.2021

By Gretchen Reynolds Does being active make us ravenous afterward and prone to eating more than we perhaps should? Or does it blunt our appetites and make it easier for us to skip that last, tempting slice of pie? A new study provides timely, if cautionary, clues. The study, which involved overweight, sedentary men and women and several types of moderate exercise, found that people who worked out did not overeat afterward at an enticing buffet lunch. However, they also did not skip dessert or skimp on portions. The findings offer a reminder during the holidays that while exercise has countless health benefits, helping us eat less or lose weight may not be among them. For most of us, exercise affects our weight and hunger in unexpected and sometimes contradictory ways. According to multiple scientific studies, few people who start to exercise drop as many pounds as the number of calories they burn working out would foretell. Some recent research suggests this occurs because our bodies stubbornly try to hang on to our fat stores, an evolutionary adaptation that protects us against (unlikely) future famines. So, if we burn calories during exercise, our bodies might nudge us to sit more afterward or reallocate energy from some bodily systems to others, reducing our overall daily energy expenditure. In this way, our bodies unconsciously compensate for many of the calories we burn exercising, reducing our chances of dropping pounds by working out. But that caloric compensation happens slowly, over the course of weeks or months, and involves energy expenditure. It has been less clear whether and how exercise influences our energy intake — that is, how many servings of food we consume — especially in the hours immediately after a workout. The evidence so far has been mixed. © 2021 The New York Times Company

Keyword: Obesity
Link ID: 28088 - Posted: 11.24.2021

Julia F. Taylor Eating disorders began to spike among young people shortly after the onset of the COVID-19 pandemic. Experts believe the increase occurred due to disruptions in daily living, emotional distress and more time spent on social media – which research has shown can lead to lower self-esteem and negative body image. One peer-reviewed study indicates that eating disorder diagnoses increased 15% in 2020 among people under 30 compared to previous years. Other studies have suggested that patients who already had an eating disorder diagnosis got worse during the pandemic. The researchers reported an increase in eating disorder symptoms along with anxiety and depression. Eating disorders include anorexia nervosa, bulimia nervosa, binge eating disorder and other specified feeding and eating disorders such as atypical anorexia. The peak age of onset is 15-25 years old, but individuals can develop eating disorders at any age. Don’t let yourself be misled. Understand issues with help from experts We are a physician and a psychotherapist who specialize in treating eating disorders in teens and young adults. We’ve seen the increased demand for eating disorder services in our own clinic. While eating disorders have historically been underdiagnosed in certain groups – specifically males, racial/ethnic minorities, and people who are higher-weight, LGBTQ or from poorer backgrounds – the recent COVID-related increase in patients presenting for care has reinforced that no group is immune from them. Here are three groups of young people who are often overlooked when it comes to eating disorders. 1. Adolescent boys and young men Historical research on diagnosing eating disorders has focused on females. This has made it harder for doctors, families and patients to recognize eating disorders in males. For example, adolescent boys may be more prone to focus on muscle strength and steroid use – indicators that are not captured in traditional, female-focused screening tools and diagnostic criteria. H © 2010–2021, The Conversation US, Inc.

Keyword: Anorexia & Bulimia
Link ID: 28059 - Posted: 11.03.2021

By Kate Conger, Kellen Browning and Erin Woo A 27-year-old YouTube star, prodded by her millions of followers with concerns about her health. A 19-year-old TikTok creator who features posts about being skinny. Teen communities throughout the internet, cleverly naming and culling their discussions to avoid detection. They present a nearly intractable problem for social media companies under pressure to do something about material on their services that many people believe is causing harm, particularly to teenagers. Those concerns came into sharp focus in recent weeks in a pair of Senate subcommittee hearings: the first featuring a Facebook executive defending her company, and the second featuring a former Facebook employee turned whistle-blower who bluntly argued that her former employer’s products drove some young people toward eating disorders. The hearings were prompted in part by a Wall Street Journal article that detailed how internal Facebook research showed Instagram, which is owned by Facebook, can make body image issues worse for some young people. On Tuesday, executives from YouTube, TikTok and Snapchat are scheduled to testify before a Senate subcommittee about the effects of their products on children. They are expected to face questions about how they moderate content that might encourage disordered eating, and how their algorithms might promote such content. “Big Tech’s exploiting these powerful algorithms and design features is reckless and heedless, and needs to change,” Senator Richard Blumenthal, a Democrat of Connecticut and the chair of the subcommittee, said in a statement. “They seize on the insecurities of children, including eating disorders, simply to make more money.” But what exactly can be done about that content — and why people create it in the first place — may defy easy answers. If creators say they don’t intend to glamorize eating disorders, should their claims be taken at face value? Or should the companies listen to users complaining about them? © 2021 The New York Times Company

Keyword: Anorexia & Bulimia; Attention
Link ID: 28049 - Posted: 10.23.2021