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Staying on the keto diet long term could carry health risks

By Meghan Rosen Maybe you’ve seen an influencer make French fries out of almond flour. Or a sandwich recipe that swaps bread for fried cheese. They’re called keto meals, and they’re largely shared for one reason: to help people lose weight. In the ketogenic diet, fat is king, and carbs are public enemy number one. Going keto means restricting carbs to the bare minimum and replacing those lost calories with fat. It’s the antithesis of the low-fat diet craze of the 1990s. Losing fat on keto diets typically means eating fat — and lots of it. The idea may sound paradoxical. But without our typical go-to energy source (sugar), our bodies learn to rely on a different type of fuel. In keto dieters, the liver converts fat into molecules called ketone bodies, which the body can burn instead of sugar. That can lead to weight loss, despite an unusually high intake of fat. Such results may explain why so many Americans have tried the keto diet on for size. “I think a lot of people look at a ketogenic diet and think, ‘I’ll lose weight, I’ll be healthier,’” says Molly Gallop, a physiologist at Earlham College in Richmond, Ind. On the surface, they may be right. But staying on the diet long-term could carry some risks, a new study in mice suggests. Mice fed a ketogenic diet for up to about a year — decades in human time — experienced health problems including glucose intolerance and signs of liver and cardiovascular disease, Gallop and her colleagues report September 19 in Science Advances. The work uncovers some potential hidden costs to going keto, says physiologist Amandine Chaix, at the University of Utah in Salt Lake City. “It’s a cautionary tale,” she says. People sticking to this high-fat plan need to be careful, she says, “because this is not a magical dietary approach.” © Society for Science & the Public 2000–2025.

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 29933 - Posted: 09.20.2025

Daily weight loss pill can help cut body weight by a fifth

Andrew Gregory Health editor A daily pill for weight loss can help people reduce their body weight by as much as a fifth, according to a trial that could pave the way for millions more people to shed pounds. The drug, called orforglipron, is manufactured by Eli Lilly and targets the same GLP-1 receptors as weight loss injections such as Mounjaro and Wegovy. In a trial of 3,127 adults, one in five people who took the once-a-day tablet for 72 weeks lost 20% or more of their body weight. Weight loss jabs have been transformative but pill versions are seen as a holy grail because they are easier to store, distribute and administer and are also expected to be cheaper, offering fresh hope for the millions of people trying to lose weight. Orforglipron is a GLP-1 agonist, a type of medication that helps lower blood sugar levels, slows the digestion of food and can reduce appetite. The weight loss seen among people taking the tablet is not as stark as that among patients taking tirzepatide (Mounjaro), which is also made by Eli Lilly, but experts believe the tablet will be more accessible and convenient compared with injections. Orforglipron is not yet approved by the US Food and Drug Administration (FDA) or regulators in other countries. Eli Lilly has said it expects substantial demand when the new pill is launched. The company published a snapshot of the results in August and the full paper detailing the findings has now been published in the New England Journal of Medicine and presented to the annual meeting of the European Association for the Study of Diabetes in Vienna, Austria. © 2025 Guardian News & Media Limited

Are ultra-processed foods really so unhealthy?

Nic Fleming In the early 2000s, Brazilian nutrition researcher Carlos Monteiro made a puzzling discovery that led to an epiphany. While trawling survey data on household spending to try to understand why rates of obesity and type 2 diabetes were rising so rapidly in his home country, he was surprised to note that people were buying smaller quantities of sugar, salt and other ingredients generally associated with these conditions than they had in previous decades. Only when Monteiro and his colleagues dug deeper did they find the culprit. People were buying less sugar to prepare cakes and desserts, but eating more of it in pre-made pastries and breakfast cereal. They were buying less salt, but consuming more of it in frozen pizzas, chicken nuggets and dehydrated packet soups. “We realized the problem was our traditional dietary patterns were being replaced by foods that are processed so many times that they can no longer be recognized in the final products. We called them ultra-processed foods.” Monteiro, a nutrition and public-health researcher at the University of São Paulo, first used the term ultra-processed food (UPF) in a paper in 2009, arguing that people interested in promoting healthy diets should focus more on the degree, extent and purpose of processing than on nutrient profiles1. It was a radical idea that caught the attention of other researchers, who, over the next decade or so, published dozens of papers linking UPFs with obesity and a range of other health problems. Governments took notice, too. In 2014, Brazil began advising people to avoid UPFs. Other countries, including France, Belgium and Israel, followed suit. Robert F. Kennedy Jr, secretary of the US Department of Health and Human Services (HHS), has been a critic of UPFs, saying in January that they are “poisoning the American people”. In May, the US government announced plans for a research agenda to support nutrition policy and improve people’s diets, in part by improving understanding of the impacts of UPFs on health. © 2025 Springer Nature Limited

The other end of the weight spectrum: Very thin people

By Ute Eberle Before weight coach Bella Barnes consults with new clients, she already knows what they’ll say. The women struggle with their weight, naturally. But they don’t want to lose pounds. They want to gain them. Her clients find themselves too thin, and they’re suffering. “Last week, I signed up a client who wears leggings that have bum pads in them,” says Barnes, who lives in Great Britain. “I’ve had another client recently that, in summer, wears three pairs of leggings just to try and make herself look a bit bigger.” These women belong to a demographic group that has been widely overlooked. As the world focuses on its billion-plus obese citizens, there remain people at the other end of the spectrum who are skinny, often painfully so, but don’t want to be. Researchers estimate that around 1.9 percent of the population are “constitutionally thin,” with 6.5 million of these people in the United States alone. YOU MAY ALSO LIKE Conceptual illustration shows three dinner plates, two at night with crescent moons are empty, representing a nightly fast, and a third with a sun theme, full of food and representing the benefits of eating during a limited time during the day. Constitutionally thin individuals often eat as much as their peers and don’t exercise hard. Yet their body mass index is below 18.5 — and sometimes as low as 14, which translates to 72 pounds on a five-foot frame — and they don’t easily gain weight. The condition is “a real enigma,” write the authors of a recent paper in the Annual Review of Nutrition. Constitutional thinness, they say, challenges “basic dogmatic knowledge about energy balance and metabolism.” It is also understudied: Fewer than 50 clinical studies have looked at constitutionally thin people, compared with thousands on unwanted weight gain. © 2025 Annual Reviews

How to Help People Stay on Their Weight-Loss Drugs

By Joshua Cohen Roughly 40 percent of adult Americans are considered obese, and weight-loss drugs have come to play a central role in medical treatment over the past few years. As of the spring of 2024, one in eight U.S. adults had taken drugs including Wegovy, Zepbound, or Ozempic, among others, for weight loss. These products belong to a class of drugs known as glucagon-like peptide-1 agonists, or GLP-1s, which can be remarkably effective, but when patients go off GLP-1s, weight rebound occurs. And as it turns out, a relatively large portion of patients discontinue these medications within one year. Prime Therapeutics, a company that manages prescription drug coverage benefits for insurers, employers, and government programs, has been documenting this phenomenon. In 2023, the company published research indicating that merely 32 percent of patients remained on their GLP-1 at the end of one year. A follow-up analysis found that by year two, only 15 percent remained on the drug. And in a new review, the company found that only 8 percent of patients remained on the drugs after three years. The main reason for discontinuation — cited by almost half of patients in a large-scale survey — is concern about the medications’ side effects. People may quit their medication after experiencing common side effects, such as uncomfortable gastrointestinal issues. They may also quit out of fear of more serious ones, like certain cancers — although research suggests GLP-1s are associated with a lower risk for many types of cancer. Additionally, some GLP-1 users may also be at risk of nutrient deficiency and muscle or bone loss without a proper diet and exercise regimen. Health and nutrition experts suggest that optimizing the benefits conferred by GLP-1s requires lifestyle interventions aimed at modifying patient behavior. GLP-1 medicines work for weight loss by curbing hunger and slowing digestion, but they don’t replace the need for improved diet and increased physical activity. Rather, these prescription pharmaceuticals and other non-GLP-1 obesity drugs work together with nutrition and exercise to promote optimal health. In an email to Undark, Jody Dushay, an assistant professor at Harvard Medical School, wrote that “nutrition and exercise hugely benefit overall health” and increase the positive effects of the medications.

What Does It Mean To Be Thirsty?

By Dan Samorodnitsky Water is the most fundamental need for all life on Earth. Not every organism needs oxygen, and many make their own food. But for all creatures, from deep-sea microbes and slime molds to trees and humans, water is nonnegotiable. “The first act of life was the capture of water within a cell membrane,” a pair of neurobiologists wrote in a recent review. Ever since, cells have had to stay wet enough to stay alive. Water is the medium in which all chemical reactions in an organism take place, and those reactions are finely tuned to a narrow range of ratios between water and salt, another essential ingredient in life’s chemistry. The cells in your body are permeable to water, so if the water-salt balance of the surrounding fluid — blood, lymph or cerebrospinal fluid, for example — is outside its healthy range, cells can swell or shrink, shrivel or potentially burst. An imbalance can cause brain cells to malfunction, losing their ability to manage ion concentrations across their membranes and propagate action potentials. Although these effects of insufficient water are felt by every cell in the body, cells themselves do not cry out in thirst. Instead, it’s the brain that monitors the body’s water levels and manifests the experience of thirst — a dry tongue, hot throat and rapid onset of malaise — which compels a behavior: acquire water. “These neural circuits that control hunger and thirst are located deep in primitive brain structures like the hypothalamus and brainstem,” said Zachary Knight (opens a new tab), a neuroscientist at the University of California, San Francisco, who recently co-authored a review paper in Neuron (opens a new tab) on the neurobiology of thirst. Because these brain areas are difficult to study — due not only to their location, but also to their composition, with many different cell types and crisscrossed circuitry — it’s only in the last decade or so that neuroscientists have begun to understand how thirst fundamentally works. The body, researchers have found, is filled with sensors that feed clues to the brain about how much water or salt an organism needs to consume. How those sensors work, or what they even are, continues to elude scientists. Their existence offers a tantalizing insight: Water may be fundamental to life, but thirst is an educated guess. © 2025 Simons Foundation

You can't outrun a bad diet. Food — not lack of exercise — fuels obesity, study finds

Maria Godoy Back in the 1800s, obesity was almost nonexistent in the United States. Over the last century, it's become common here and in other industrialized nations, though it remains rare among people who live more traditional lifestyles, such as the Hadza hunter-gatherers of Tanzania. So what's changed? One common explanation is that as societies have developed, they've also become more sedentary, and people have gotten less active. The assumption is that as a result, we burn fewer calories each day, contributing to an energy imbalance that leads to weight gain over time, says Herman Pontzer, a professor of evolutionary biology and global health at Duke University who studies how human metabolism has evolved. Sponsor Message But in a major new study published in the journal PNAS, Pontzer and an international team of collaborators found that's not the case. They compared the daily total calorie burn for people from 34 different countries and cultures around the world. The people involved ran the spectrum from hunter-gatherers and farming populations with low obesity rates, to people in more sedentary jobs in places like Europe and the U.S., where obesity is widespread. "Surprisingly, what we find is that actually, the total calories burned per day is really similar across these populations, even though the lifestyle and the activity levels are really different," says Pontzer. And that finding offers strong evidence that diet — not a lack of physical activity — is the major driver of weight gain and obesity in our modern world. © 2025 npr

By Laura Sanders GLP-1 drugs may possess a new power: Easing migraines. In a small, preliminary study, a GLP-1 drug nearly halved the number of days people spent with a migraine in a given month. The results, presented June 21 at the European Academy of Neurology Congress in Helsinki, Finland, expand the possible benefits of the powerful new class of obesity and diabetes drugs. These pernicious, debilitating headaches are estimated to affect one billion people worldwide. Earlier studies have shown that GLP-1 agonists can reduce the pressure inside the skull, a squeeze that’s been implicated in migraines. Neurologist Simone Braca of the University of Naples Federico II in Italy and his colleagues explored whether liraglutide, an older relative of Ozempic and Wegovy, might help migraine sufferers. Thirty-one adults, 26 of them women, got daily injections of liraglutide for 12 weeks. These adults all had obesity and continued to take their current migraine medicines too. At the start of the experiment, participants had headaches on about 20 days out of a month. After 12 weeks of liraglutide, the average number dropped to about 11 days. “Basically, we observed that patients saw their days with headache halved, which is huge,” Braca says. Participants’ weight stayed about the same during the trial, suggesting that headache reductions weren’t tied to weight loss. If the results hold up in larger studies, they may point to treatments for migraine sufferers who aren’t helped by existing drugs. The results may also lead to a deeper understanding of the role of pressure inside the head in migraines, Braca says. © Society for Science & the Public 2000–2025.

Related chapters from BN: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 29846 - Posted: 07.02.2025

How your brain controls ageing — and why zombie cells could be key

Diana Kwon There might be a paradox in the biology of ageing. As humans grow older, their metabolisms tend to slow, they lose muscle mass and they burn many fewer calories. But certain cells in older people appear to do the exact opposite — they consume more energy than when they were young. These potential energy hogs are senescent cells, older cells that have stopped dividing and no longer perform the essential functions that they used to. Because they seem idle, biologists had assumed that zombie-like senescent cells use less energy than their younger, actively replicating counterparts, says Martin Picard, a psychobiologist at Columbia University in New York City. But in 2022, Gabriel Sturm, a former graduate student of Picard’s, painstakingly observed the life course of human skin cells cultured in a dish1 and, in findings that have not yet been published in full, found that cells that had stopped dividing had a metabolic rate about double that of younger cells. For Picard and his colleagues, the energetic mismatch wasn’t a paradox at all: ageing cells accumulate energetically costly forms of damage, such as alterations in DNA, and they initiate pro-inflammatory signalling. How that corresponds with the relatively low energy expenditure for ageing organisms is still unclear, but the researchers hypothesize that this tension might be an important driver of many of the negative effects of growing old, and that the brain might be playing a key part as mediator2. As some cells get older and require more energy, the brain reacts by stripping resources from other biological processes, which ultimately results in outward signs of ageing, such as greying hair or a reduction in muscle mass (see ‘Energy management and ageing’). Picard and his colleagues call this concept the ‘brain–body energy-conservation model’. And although many parts of the hypothesis are still untested, scientists are working to decipher the precise mechanisms that connect the brain to processes associated with ageing, such as senescence, inflammation and the shortening of telomeres — the stretches of repetitive DNA that cap the ends of chromosomes and protect them. © 2025 Springer Nature Limited

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 29836 - Posted: 06.18.2025

A genetic test may predict which weight loss drugs work best for patients

By Tina Hesman Saey People trying to lose weight often count calories, carbs, steps and reps and watch the scales. Soon, they may have another number to consider: a genetic score indicating how many calories a person needs to feel full during a meal. This score may help predict whether someone will lose more weight on the drugs liraglutide or phentermine-topiramate, researchers report June 6 in Cell Metabolism. A separate study, posted to medRXiv.org in November, suggests that individuals with a higher genetic propensity for obesity benefit less from semaglutide compared to those with a lower genetic predisposition. Such genetic tests may one day help doctors and patients select personalized weight-loss treatments, some researchers say. But the genetic scores “are not perfect predictors of drug response,” says Paul Franks, a genetic epidemiologist at Queen Mary University of London who was not involved in either study. “They show a tendency.” For the Cell Metabolism study, Mayo Clinic researchers measured how many calories it took for about 700 adults with obesity to feel full when given an all-you-can-eat meal of lasagna, pudding and milk. The calorie intake varied widely, ranging from about 140 to 2,200 calories, with men generally needing more than women. The team used machine learning to compile a genetic score based on variants of 10 genes associated with obesity. That score is designed to reflect the calories people required to feel full. Then, the Mayo team and colleagues from Phenomix Sciences Inc, headquartered in Menlo Park, Calif., conducted two clinical trials. In one 16-week trial, people with obesity received either a placebo or liraglutide — a GLP-1 drug branded as Saxenda. GLP-1s are a class of diabetes drugs that have shown promise with weight loss. People with a lower genetic score lost more weight on liraglutide than those with higher genetic scores. © Society for Science & the Public 2000–2025.

How to keep weight off after obesity drugs

Elie Dolgin Sheree had maintained a healthy weight for 15 years, thanks to a surgery that wrapped a silicone ring around the top of her stomach. But when the gastric band repeatedly slipped and had to be removed, the weight came back — fast. She gained nearly 20 kilograms in just 2 months. Frustrated, she turned to the latest generation of anti-obesity medications, hoping to slow the rapid weight gain. She cycled through various formulations of the blockbuster therapies semaglutide (sold under the brand names Ozempic and Wegovy) and tirzepatide (sold as Zepbound for weight loss), finding some success with higher doses of these drugs, which mimic the effects of the appetite-suppressing hormone GLP-1. But each time, drug shortages disrupted her treatment, forcing her to start again with a new formulation or to go without the drugs for weeks. Tired of the uncertainty around the therapies, she decided to try something different. Sheree, who asked that her middle name be used to protect her privacy, underwent two minimally invasive procedures designed to reduce the size of her stomach and to blunt hunger cues. Developed over the past two decades, these ‘endoscopic’ procedures — performed using flexible tubes inserted through the mouth, and no scalpels — are just one part of a growing toolkit to help people who want to move away from GLP-1 therapy. More-conventional bariatric surgeries, used routinely since the 1980s to reroute the flow of food through the gut or to restrict the stomach’s size, might also gain wider appeal. And the search is picking up for other drugs that could offer lasting alternatives for a post-GLP-1 population. That momentum is driven by a convergence of factors: chronic shortages of GLP-1 therapies, high costs, insurance barriers and debilitating side effects. As a result, many people who start the drugs ultimately stop — with discontinuation rates in clinical trials ranging from 37% to 81% in the first year1. And once treatment ends, the weight lost often piles back on. © 2025 Springer Nature Limited

Worm-inspired treatments inch toward the clinic

By Amber Dance The experiment was a striking attempt to investigate weight control. For six weeks, a group of mice gorged on lard-enriched mouse chow, then scientists infected the mice with worms. The worms wriggled beneath the animals’ skin, migrated to blood vessels that surround the intestines, and started laying eggs. Bruno Guigas, a molecular biologist at the Leiden University Center for Infectious Diseases in the Netherlands, led this study some years back and the results, he says, were “quite spectacular.” The mice lost fat and gained less weight overall than mice not exposed to worms. Within a month or so, he recalls, the scientists barely needed their scale to see that the worm-infested mice were leaner than their worm-free counterparts. Infection with worms, it seems, reversed obesity, the researchers reported in 2015. While it’s true that worms gobble up food their hosts might otherwise digest, that doesn’t seem to be the only mechanism at work here. There’s also some intricate biology within the emerging scientific field of immunometabolism. Over the past couple of decades, researchers have recognized that the immune system doesn’t just fight infection. It’s also intertwined with organs like the liver, the pancreas and fat tissue, and implicated in the progression of obesity and type 2 diabetes. These and other metabolic disorders generate a troublesome immune response — inflammation — that worsens metabolism still further. Metabolic disease, in other words, is inflammatory disease. Scientists have also observed a metabolic influence of worms in people who became naturally infected with the parasites or were purposely seeded with worms in clinical trials. While the physiology isn’t fully understood, the worms seem to dampen inflammation, as discussed in the 2024 Annual Review of Nutrition.

Related chapters from BN: 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: 29828 - Posted: 06.14.2025

Weight loss jabs in obese children can help avoid mealtime rows

Anna Bawden in Málaga and agency Giving obese children weight loss jabs works and could help avoid arguments over mealtimes, according to research. Clinicians treating very obese children at a hospital in Sweden analysed whether liraglutide injections could be used as well as diet and lifestyle changes to increase weight loss. In real-life analysis of 1,000 children under 16 with severe obesity over a number of years, about a quarter of patients in 2023 were given the weight loss drug liraglutide in addition to receiving intensive health behaviour and lifestyle treatment at the National Childhood Obesity Centre in Stockholm. The clinicians found that nearly a third of these children dropped enough weight to improve their health, compared with about 27% in earlier treated groups with no access to the drugs. Patients starting the programme in 2024 have been given semaglutide but results from these children are not yet available. Semaglutide, better known as Wegovy, and liraglutide, sold as Saxenda, are both GLP-1 receptor agonists, which help curb appetite. In the UK they are available on the NHS only for adults with a BMI above 35 with a weight-related condition, although in certain circumstances specialist paediatric clinics can prescribe them. Dr Annika Janson, of Karolinska university hospital in Sweden, the lead author of the study, whose findings were presented at the European Congress on Obesity, said the beneficial impact of weight loss jabs on children’s weight could accelerate in future years. © 2025 Guardian News & Media Limited

What Nearly Brainless Rodents Know About Weight Loss and Hunger

By Gina Kolata Do we really have free will when it comes to eating? It’s a vexing question that is at the heart of why so many people find it so difficult to stick to a diet. To get answers, one neuroscientist, Harvey J. Grill of the University of Pennsylvania, turned to rats and asked what would happen if he removed all of their brains except their brainstems. The brainstem controls basic functions like heart rate and breathing. But the animals could not smell, could not see, could not remember. Would they know when they had consumed enough calories? To find out, Dr. Grill dripped liquid food into their mouths. “When they reached a stopping point, they allowed the food to drain out of their mouths,” he said. Those studies, initiated decades ago, were a starting point for a body of research that has continually surprised scientists and driven home that how full animals feel has nothing to do with consciousness. The work has gained more relevance as scientists puzzle out how exactly the new drugs that cause weight loss, commonly called GLP-1s and including Ozempic, affect the brain’s eating-control systems. The story that is emerging does not explain why some people get obese and others do not. Instead, it offers clues about what makes us start eating, and when we stop. While most of the studies were in rodents, it defies belief to think that humans are somehow different, said Dr. Jeffrey Friedman, an obesity researcher at Rockefeller University in New York. Humans, he said, are subject to billions of years of evolution leading to elaborate neural pathways that control when to eat and when to stop eating. © 2025 The New York Times Company

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 29762 - Posted: 04.26.2025

Companies seek a second obesity treatment revolution—in pill form

By Rachel Brazil Drugs that mimic glucagonlike peptide-1 (GLP-1), such as semaglutide—marketed as Ozempic or Wegovy—have revolutionized the treatment of obesity and type 2 diabetes, but they have major drawbacks. “[They] are expensive to manufacture, they have to be refrigerated, and they often have to be injected because they cannot go through the gastrointestinal tract without being degraded,” explains Alejandra Tomas, a cell biologist at Imperial College London who studies the cellular receptor GLP-1 drugs target. That’s all because they consist of peptides, or long chains of amino acids. A small-molecule version of the therapy, on the other hand, could be given as a daily pill and would be much cheaper to produce. Companies including Eli Lilly, Pfizer, and Roche have launched clinical trials of such compounds. Results from Lilly’s first phase 3 trial of its oral drug are expected later this year. But Pfizer announced this week it was halting development of its candidate after signs of liver injury in a trial participant. The candidates furthest along in development activate the same receptors as peptide drugs do, in much the same way. But several firms are exploring more innovative small molecules that target different sites on those receptors—and could lead to even more effective treatments with fewer side effects. “In the next 4 or 5 years, this field will mature and more patients ultimately should be able to get these medicines,” says Kyle Sloop, a molecular biologist at Lilly Research Laboratories. By mimicking a natural hormone, semaglutide and other drugs in its class help regulate blood sugar by increasing insulin secretion from the pancreas in response to glucose, and suppress appetite by slowing down digestion. The first generation of peptide drugs were essentially copies of GLP-1, with modifications to prevent the peptide from quickly degrading once in the body. Novo Nordisk first won U.S. approval for semaglutide to treat type 2 diabetes in 2017. It needed to be injected, but in 2019 the company added a pill form, which includes an absorption-enhancing ingredient that allows the peptide to penetrate the stomach wall. However, it requires a high dose and has to be taken while fasting, with minimal liquid.

Why there's always room for dessert, according to brain science

By Emily Kwong You probably know the feeling of having a hearty meal at a restaurant, and feeling full and satisfied … only to take a peek at the dessert menu and decide the cheesecake looks just irresistible. So why is it that you just absolutely couldn't have another bite, but you somehow make an exception for a sweet treat? Or as Jerry Sienfeld might put it back in the day "Whhaaaat's the deal with dessert?!" Scientists now have a better understanding of the neural origins of this urge thanks to a recent study published in the journal Science. Sponsor Message Working with mice, researchers tried to set up a scenario similar to the human experience described above. They started by offering a standard chow diet to mice who hadn't eaten since the previous day. That "meal" period lasted for 90 minutes, and the mice ate until they couldn't eat any more. Then it was time for a 30-minute "dessert" period. The first round of the experiment, researchers offered mice more chow for dessert, and the mice ate just a little bit more. The second time around, during the "dessert" period, they offered a high sugar feed to the mice for 30 minutes. The mice really went for the sugary feed, consuming six times more calories than when they had regular chow for dessert. In the mice, researchers monitored the activity of neurons that are associated with feelings of fullness, called POMC neurons. They're located in a part of the brain called the hypothalamus, which is "very important for promoting satiety," says Henning Fenselau, one of the study authors and a researcher at the Max Planck Institute for Metabolism Research in Cologne, Germany. © 2025 npr

Dozens of new obesity drugs are coming: these are the ones to watch

By Elie Dolgin For Kristian Cook, every pizza box he opened was another door closed on the path to overcoming obesity. “I had massive cravings for pizza,” he says. “That was my biggest downfall.” At 114 kilograms and juggling a daily regimen of medications for high cholesterol, hypertension and gout, the New Zealander resolved to take action. In late 2022, at the age of 46, Cook joined a clinical trial that set out to test a combination of the weight-loss drug semaglutide — better known by its brand names, Ozempic or Wegovy — and an experimental drug designed to preserve muscle while shedding fat. Muscle loss is a big concern for people on anti-obesity medications such as semaglutide. These ‘GLP-1 agonists’ mimic a natural gut hormone — glucagon-like peptide 1 — to suppress appetite and regulate metabolism. But reducing calories leads to an energy deficit, which the body often makes up for by burning muscle. The experimental drug that Cook received, called bimagrumab, seems to counteract this muscle loss. It’s one of more than 100 anti-obesity drug candidates that are in various stages of development. The next wave of medications, which are likely to hit pharmacy shelves in the next few years, resemble drugs that are already on the market. But close behind are numerous therapies being developed specifically for their muscle-sparing weight-loss potential. Dozens more are aimed at different biological pathways and could redefine obesity treatment in decades to come. “We’re working to create the next generation of healthy weight-loss solutions,” says Philip Larsen, who played a key part in the early development of GLP-1 drugs and is now chief executive of SixPeaks Bio, an obesity-focused start-up company in Basel, Switzerland. The surge in anti-obesity drug development has been made possible by the blockbuster success of semaglutide and its rival drug tirzepatide — sold as Zepbound or Mounjaro. These drugs have unlocked the potential for a global market that is projected to surpass US$100 billion by the end of the decade. © 2025 Springer Nature Limited

New obesity definition sidelines BMI to focus on health

By Giorgia Guglielmi Amid the rising buzz around Ozempic and similar weight-loss drugs, a group of 58 researchers is challenging the way obesity is defined and diagnosed, arguing that current methods fail to capture the complexity of the condition. They offer a more nuanced approach. The group’s revised definition, published in The Lancet Diabetes & Endocrinology1 on 14 January, focuses on how excess body fat, a measure called adiposity, affects the body, rather than relying only on body mass index (BMI), which links a person’s weight to their height. They propose two categories: preclinical obesity, when a person has extra body fat but their organs work normally, and clinical obesity, when excess fat harms the body’s organs and tissues. This shift could improve clinical care, public-health policies and societal attitudes toward obesity, says Elisabeth van Rossum, an endocrinologist at the Erasmus University Medical Center Rotterdam in the Netherlands. “Now the idea is, eat less, move more, and you’ll lose weight,” says van Rossum, who wasn’t involved in the work. Although a healthy lifestyle is important, she adds, “if it would be so simple, we wouldn’t have an epidemic, and this paper is an excellent contribution to the discussion about the complexity of obesity”. Global problem More than 1 billion people worldwide live with obesity, and the condition is linked to about 5 million deaths every year2 from disorders such as diabetes and cardiovascular disease. Because it is easy to measure and compare, BMI has long been used as a tool to diagnose obesity. But it doesn’t offer a full picture of a person’s health, because it doesn’t account for differences in body composition, such as muscle versus fat. © 2025 Springer Nature Limited

Restricting calories may extend life. Can this molecule do it without the hunger pangs?

By Mitch Leslie It’s a dismaying thought during a holiday season full of cookies and big meals, but severely restricting calories consumed is one of the best supported strategies for a healthier, longer life. Slicing food consumption stretches the lives of animals in lab experiments, and similar deprivation seems to improve health in people, although almost no one can sustain such a calorie-depleted diet for long. Now, researchers in China studying animals on lean rations have identified a molecule made by gut bacteria that delivers some of the same benefits. When given on its own, the molecule makes flies and worms live longer and refurbishes age-weakened muscles in mice, all without leaving the animals hungry. Although the molecule’s effects in people remain unclear, the discovery is “a really important step forward,” says gerontologist Richard Miller of the University of Michigan, who wasn’t connected to the research. The work, reported in two studies today in Nature, “is very thorough.” Research over the past 90 years has shown that calorie restriction—which to scientists typically means a diet with between 10% and 50% fewer calories than normal—can extend longevity in organisms as diverse as yeast, nematodes, and mice. One experiment also found an effect in monkeys. Trials to test whether calorie restriction increases human life span would take too long, but participants in the 2-year CALERIE trial, which ran from 2007 to 2010 and aimed to cut calorie intake by 25%, enjoyed a slew of improvements, including lower levels of low-density lipoprotein cholesterol, increased sensitivity to insulin, and a 10% reduction in weight. However, the trial also illustrates what makes calorie restriction so challenging: Participants on average cut their caloric intake by only half the experiment’s goal. So, scientists have been hunting for molecules that trigger health-promoting, longevity-stretching effects without privation. To identify new candidates, molecular biologist and biochemist Sheng-Cai Lin of Xiamen University and colleagues took a systematic approach, analyzing the levels of more than 1200 metabolic molecules in blood samples from calorically restricted mice and from counterparts with no dietary limits. They discovered that just over 200 molecules became more abundant when food was in short supply.

To beat the heat, hypothalamus neurons in mice ramp up their firing

By Calli McMurray A strong, long-lasting sensory stimulus—be it visual, auditory, olfactory or tactile—triggers plasticity in the neurons that respond to it. But as a scientist long interested in temperature, Jan Siemens wondered: Does the same principle apply to prolonged heat? In mammals, the body changes when temperatures soar—blood vessels dilate, heat-generating brown adipose tissue shuts off, the heart rate lowers, locomotion slows—but it wasn’t clear if the brain played a role in these changes, or even changed itself, says Siemens, professor of pharmacology at the University of Heidelberg. Siemens and his team started a search for heat-induced neuronal plasticity in the ventromedial preoptic area of the hypothalamus (VMPO) in mice. They chose the region because of its involvement in regulating body temperature and generating fever; neurons there receive temperature information downstream from cells innervating the skin, whereas others are themselves warm-sensitive. They identified cells to target by measuring the expression of c-FOS, a gene that is activated by neuronal activity, after housing the mice at 36 degrees Celsius for up to eight hours. At first, however, their investigative trail went cold. In brain slices, those warm-responding cells showed only slight and inconsistent changes in synaptic plasticity. “That was actually quite humbling and disappointing,” Siemens says. But then they made a “serendipitous observation,” he says: A subgroup of neurons expressing the leptin receptor became almost constantly active after four weeks of heat acclimation. The firing was so synchronized and regular that Wojciech Ambroziak, a postdoctoral scholar in the lab at the time, described it as “soldiers marching in a line,” Siemens recalls. © 2024 Simons Foundation

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