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

Infants who sleep longer through the night and with fewer interruptions may be less likely to become overweight during their first six months of life, according to a study published in the journal SLEEP(link is external). While the research only showed a link – not a cause-effect relationship – between infants’ sleep and weight, the findings suggest that newborns can reap some of the same health benefits that others get from consistent, quality shut-eye. The research emerged from the Rise and SHINE (Sleep Health in Infancy & Early Childhood) study, which analyzes ways sleep may influence a newborn’s growth and development. The five-year study is being supported in part by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. “What is particularly interesting about this research is that the sleep-obesity association we see across the lifespan appears in infancy and may be predictive of future health outcomes,” said Marishka K. Brown, Ph.D., director of the National Center on Sleep Disorders Research, located within the NHLBI. Brown noted that multiple studies have shown links between good sleep and improved health. For children, this includes a reduced risk of developing obesity and diabetes, while supporting development, learning, and behavior. In the current study, researchers observed 298 newborns and found that for every hourly increase in nighttime sleep, measured between 7 p.m. and 8 a.m., the infants were 26% less likely to become overweight. Likewise, for each reduction in nighttime awakening, they were 16% less likely to become overweight.

Keyword: Sleep; Obesity
Link ID: 28047 - Posted: 10.23.2021

For years, Theresa Babb blamed herself for her obesity. "It was always my fault," she told The Current. "Who else's fault would it be?" She says she spent thousands of dollars trying to lose weight, even going so far as to try commercial weight-loss programs like Weight Watchers and Jenny Craig. She also sought medical help from health-care providers, but she found some of them weren't willing to discuss her weight with her aside beyond uttering clichés about eating less or working out more. "I don't understand why a health-care professional would be afraid of talking to somebody or be uncomfortable about talking with a patient about health," she said. Nothing seemed to work for Babb, and she said she felt like a "failure" for not succeeding. That was until she met obesity specialist Dr. Laura Reardon two years ago. "One of the very first things that Dr. Reardon said to me … was 'It's not your fault,'" she said. "And it was hearing those words for the first time in my life that changed everything for me." According to Statistics Canada data from 2018, 7.3 million Canadian adults reported heights and weights classified as obese. Another 9.9 million Canadian adults were classified as overweight. Combined, these numbers represent 63.1 per cent of the Canadian adult population. Reardon said Babb's journey is one shared with millions of Canadians. "A lot of patients who come to see me probably have experiences like lots of the people out there, which is they've tried everything," she said. "They've gone to all these commercial weight loss programs. They've hired personal trainers. They've gone to the gym." ©2021 CBC/Radio-Canada.

Keyword: Obesity
Link ID: 28045 - Posted: 10.23.2021

by Angie Voyles Askham The gut microbiome is having a moment. An explosion of research over the past decade has delved into a possible connection between the microbiome and brain conditions, including autism. Once-fringe microbial treatments for autism, such as fecal transplants and probiotic pills, are receiving serious scientific attention and funding. It’s still an open question, however, whether the microbiome has a direct effect on autism traits. The most promising data supporting this idea involve altering a mouse’s gut flora, but it is not clear exactly what the mechanism is or if this work translates to people. And the evidence from human studies linking microbes to autism is thin, if a 2021 review of the literature is any guide. Adding to the uncertainty, new unpublished data from one of the largest human studies yet suggests that the link between an atypical gut microbiome and autism is driven solely by a difference in diet. At least four small firms are spearheading early-stage trials of ‘bug as drug’ treatments for autism-associated traits. But until those trials play out, the role of the microbiome in autism is far from clear, says Gaspar Taroncher-Oldenburg, a consultant on microbiome research for the Simons Foundation, Spectrum’s parent organization. “There’s no denying that the microbiome is part of the [autism] conversation,” Taroncher-Oldenburg says. “But it’s a very complex conversation, and we’re only starting to scratch the surface.” A potential connection between the gut microbiome and autism first surfaced in the 1990s, after parents reported changes in their autistic children’s behavior when the children took antibiotics, which kill some gut bacteria. A 2000 study following up on this idea showed that 8 of 10 autistic children taking an antibiotic had temporary improvements in their speech and sociability. Later work associated an atypical gut microbiome with unusual social behaviors in mice. © 2021 Simons Foundation

Keyword: Autism
Link ID: 28043 - Posted: 10.20.2021

Allison Aubrey The "diet" in diet drinks may be a false promise for some soda lovers. True, they deliver the fizz and taste of a soda experience, without the calories. Yet, new research shows they also can leave people with increased food cravings. A study published recently in JAMA Network Open adds to the evidence that drinks made with sucralose may stimulate the appetite, at least among some people, and the study gives some clues as to why. "We found that females and people with obesity had greater brain reward activity" after consuming the artificial sweetener, says study author Katie Page, a physician specializing in obesity at the University of Southern California. Both groups also had a reduction in the hormone that inhibits appetite, and they ate more food after they consumed drinks with sucralose, compared with after regular sugar-sweetened drinks. In contrast, the study found males and people of healthy weight did not have an increase in either brain reward activity or hunger response, suggesting they're not affected in the same way. The study notes that most earlier research focused on males and people of normal weight. But this finding suggests that diet drinks sweetened with sucralose could be disadvantageous to the people who could benefit most from an effective diet strategy. © 2021 npr

Keyword: Obesity; Sexual Behavior
Link ID: 28027 - Posted: 10.09.2021

By Gretchen Reynolds For better health and a longer life span, exercise is more important than weight loss, especially if you are overweight or obese, according to an interesting new review of the relationships between fitness, weight, heart health and longevity. The study, which analyzed the results of hundreds of previous studies of weight loss and workouts in men and women, found that obese people typically lower their risks of heart disease and premature death far more by gaining fitness than by dropping weight or dieting. The review adds to mounting evidence that most of us can be healthy at any weight, if we are also active enough. I have written frequently in this column about the science of exercise and weight loss, much of which is, frankly, dispiriting, if your goal is to be thinner. This past research overwhelmingly shows that people who start to exercise rarely lose much, if any, weight, unless they also cut back substantially on food intake. Exercise simply burns too few calories, in general, to aid in weight reduction. We also tend to compensate for some portion of the meager caloric outlay from exercise by eating more afterward or moving less or unconsciously dialing back on our bodies’ metabolic operations to reduce overall daily energy expenditure, as I wrote about in last week’s column. Glenn Gaesser, a professor of exercise physiology at Arizona State University in Phoenix, is well versed in the inadequacies of workouts for fat loss. For decades, he has been studying the effects of physical activity on people’s body compositions and metabolisms, as well as their endurance, with a particular focus on people who are obese. Much of his past research has underscored the futility of workouts for weight loss. In a 2015 experiment he oversaw, for instance, 81 sedentary, overweight women began a new routine of walking three times a week for 30 minutes. After 12 weeks, a few of them had shed some body fat, but 55 of them had gained weight. In other studies from Dr. Gaesser’s lab, though, overweight and obese people with significant health problems, including high blood pressure, poor cholesterol profiles or insulin resistance, a marker for Type 2 diabetes, showed considerable improvements in those conditions after they started exercising, whether they dropped any weight or not. Seeing these results, Dr. Gaesser began to wonder if fitness might enable overweight people to enjoy sound metabolic health, whatever their body mass numbers, and potentially live just as long as thinner people — or even longer, if the slender people happened to be out of shape. © 2021 The New York Times Company

Keyword: Obesity
Link ID: 28024 - Posted: 10.06.2021

By Kim Tingley It’s simple, we are often told: All you have to do to maintain a healthy weight is ensure that the number of calories you ingest stays the same as the number of calories you expend. If you take in more calories, or energy, than you use, you gain weight; if the output is greater than the input, you lose it. But while we’re often conscious of burning calories when we’re working out, 55 to 70 percent of what we eat and drink actually goes toward fueling all the invisible chemical reactions that take place in our body to keep us alive. “We think about metabolism as just being about exercise, but it’s so much more than that,” says Herman Pontzer, an associate professor of evolutionary anthropology at Duke University. “It’s literally the running total of how busy your cells are throughout the day.” Figuring out your total energy expenditure tells you how many calories you need to stay alive. But it also tells you “how the body is functioning,” Pontzer says. “There is no more direct measure of that than energy expenditure.” Though scientists have been studying metabolism for at least a century, they have not been able to measure it precisely enough — in real-world conditions, in enough people, across a broad-enough age range — to see how it changes throughout the human life span. It is clear that the bigger someone is, the more cells they have, and thus the more total calories they burn per day. But it has been much harder to assess whether variables like age, sex, lifestyle and illness influence our rate of energy expenditure. This lack of data led to assumptions rooted in personal experience: for instance, that significant hormonal changes like those that take place during puberty and menopause cause our metabolism to speed up or slow down, prompting us to burn more or fewer calories per day; or that men have inherently faster metabolisms than women, because they seem able to shed pounds more easily; or that our energy expenditure slows in midlife, initiating gradual and inevitable weight gain. “I’m in my 40s; I feel different than I did in my 20s — I buy it, too,” Pontzer says. “All that intuition was never backed up by data. It just seemed so sure.” © 2021 The New York Times Company

Keyword: Obesity
Link ID: 27994 - Posted: 09.15.2021

Natalie Grover Losing weight through exercise appears to be more difficult for obese people, research suggests. Initially, researchers thought that the total energy we spend in a day is the sum of energy expended due to activity (ranging from light gardening to running a marathon) and energy used for basic functioning (what keeps us ticking even when we are doing nothing, such as immune function and wound healing). But preliminary lab research indicates that that simple addition could be misleading – estimates of total daily expenditure tend to be less than the sum of baseline and activity expenditure in individuals. To explore this further, a group of international scientists analysed measurements of energy expenditure from 1,754 adults from a dataset collected over decades and supplied by the International Atomic Energy Agency. They found that increasing levels of activity by exercising more, for instance, led to each person’s body compensating by limiting the energy expended on basic metabolic functions over a longer period, according to the study published in the journal Current Biology. For instance, if you go for a run and your activity tracker says you burned 300 calories (and you didn’t eat any differently) – you may assume that your total daily energy expenditure went up by 300 calories. That may be the case in the short term, but over the long term the body starts to compensate for this extra energy exertion by reducing the energy spent on other processes, said lead author Prof Lewis Halsey from the University of Roehampton. “It’s like the government trying to balance the budget – if it’s spending more on education for instance, then it might need to spend less on roads,” he said. © 2021 Guardian News & Media Limited

Keyword: Obesity
Link ID: 27971 - Posted: 09.01.2021

By Gina Kolata Everyone knows conventional wisdom about metabolism: People put pounds on year after year from their 20s onward because their metabolisms slow down, especially around middle age. Women have slower metabolisms than men. That’s why they have a harder time controlling their weight. Menopause only makes things worse, slowing women’s metabolisms even more. All wrong, according to a paper published Thursday in Science. Using data from nearly 6,500 people, ranging in age from 8 days to 95 years, researchers discovered that there are four distinct periods of life, as far as metabolism goes. They also found that there are no real differences between the metabolic rates of men and women after controlling for other factors. The findings from the research are likely to reshape the science of human physiology and could also have implications for some medical practices, like determining appropriate drug doses for children and older people. “It will be in textbooks,” predicted Leanne Redman, an energy balance physiologist at Pennington Biomedical Research Institute in Baton Rouge, La., who also called it “a pivotal paper.” Rozalyn Anderson, a professor of medicine at the University of Wisconsin-Madison, who studies aging, wrote a perspective accompanying the paper. In an interview, she said she was “blown away” by its findings. “We will have to revise some of our ideas,” she added. But the findings’ implications for public health, diet and nutrition are limited for the moment because the study gives “a 30,000-foot view of energy metabolism,” said Dr. Samuel Klein, who was not involved in the study and is director of the Center for Human Nutrition at the Washington University School of Medicine in St. Louis. He added, “I don’t think you can make any new clinical statements” for an individual. When it comes to weight gain, he says, the issue is the same as it has always been: People are eating more calories than they are burning. Metabolic research is expensive, and so most published studies have had very few participants. But the new study’s principal investigator, Herman Pontzer, an evolutionary anthropologist at Duke University, said that the project’s participating researchers agreed to share their data. There are more than 80 co-authors on the study. By combining efforts from a half dozen labs collected over 40 years, they had sufficient information to ask general questions about changes in metabolism over a lifetime. © 2021 The New York Times Company

Keyword: Obesity
Link ID: 27949 - Posted: 08.14.2021