Latest news with #PNAS
Yahoo
12 hours ago
- Science
- Yahoo
Optimists Are Alike, but Pessimists Are Unique, Brain Scan Study Suggests
Optimists have similar patterns of brain activation when they think about the future—but pessimists are all different from one another, a brain scan study suggests 'All happy families are alike; each unhappy family is unhappy in its own way.' This is the first line of Leo Tolstoy's novel Anna Karenina, and it may hold a kernel of truth that goes beyond family dynamics. In a recent study of optimism, neuroscientists found an equivalent principle at play: optimists shared similar patterns of activity in a key brain region when they imagined future events, but each pessimist's brain patterns was unique. The results help neuroscientists understand what distinguishes optimism from pessimism in the brain. This is an important question because optimism is associated with better physical, mental and social health. The results were published on Monday in the Proceedings of the National Academy of Sciences USA. 'We tend to think of imagining the future as a deeply personal, subjective act,' says Kuniaki Yanagisawa, the study's lead author and a psychologist at Kobe University in Japan. 'Our study, however, shows that—especially for optimists—the way our brains do this can be similar' and suggests that such shared cognitive frameworks for imagining the future might explain why we 'click' with some people, he says. Prior studies have shown that optimists have larger social networks and higher acceptance by their peers. Yanagisawa wanted to understand 'whether this social success is just about personality,' he says, 'or if optimists might share a fundamental brain mechanism that makes it easier for them to form social connections.' [Sign up for Today in Science, a free daily newsletter] The researchers scanned participants in a functional magnetic resonance imaging (fMRI) machine while they imagined specific future events happening to either them or their spouse. Some of the events were positive; others were neutral or negative. Afterward the team had the participants take a questionnaire to determine their level of optimism or pessimism. The researchers conducted the study twice, once in a group of 37 participants and again in a group of 50. To analyze the brain scans, the researchers zoomed in on one region that's particularly active while imagining future events: the medial prefrontal cortex, located in the middle of the very front of the brain. They compared patterns of brain activation in each possible pair of participants and used statistical tests to determine how similar the activations were to each other in these pairs. The team found that only pairs consisting of two optimistic participants had similar brain activation; pairs where one or both participants were more pessimistic were dissimilar to each other. The researchers also found that optimistic people showed bigger differences between brain patterns for emotionally positive and negative events than pessimists did. A few prior studies of 'positive' social traits have shown similar results. A 2022 brain scan study showed that people who held a central position in their social network have similar activation patterns to one another—but that less central people had a lot of individual differences, or idiosyncrasies. The same pattern held true in another study of people with low versus high levels of loneliness. Elisa Baek, a social neuroscientist now at the University of Southern California and lead author of those two studies, refers to these results as examples of the 'Anna Karenina principle,' the idea that successful endeavors have similar characteristics but that unsuccessful ones are each different in their own way. 'One intriguing interpretation [of the optimism study], consistent with the Anna Karenina principle, is that there may be many different ways for a person to be pessimistic, while optimistic people tend to converge on a few shared mental models of a hopeful future,' Baek says. Together, these studies 'may point to a more general principle—that being 'on the same page' as others is a foundational mechanism that underlies the experience of social connection.' If there is an Anna Karenina principle at work for positive social traits, what would be causing it? After all, the traits we deem 'positive' vary greatly among different societies, so there's a risk of cultural bias. Yanagisawa thinks that these cultural values could actually be driving the effect—they orient people toward a specific goal that is valued in a society, such as being optimistic or having a lot of social connections, perhaps leading those individuals to behave and think similarly over time. It's also possible that optimism, as measured in this study, is picking up on related traits such as people's level of loneliness or position in a social network. 'These convergent findings raise an important question about the overlap between constructs such as optimism, loneliness and network centrality,' Baek says. 'Because the new study didn't control for loneliness or social network position, and my prior work didn't control for optimism, it is unclear how much these dimensions are overlapping or distinct.' Optimism and pessimism aren't unchanging traits; they tend to shift with age, although the trajectories vary from culture to culture. Nor is optimism an unquestioned good. 'Extreme optimism might not always be a good thing because we might not plan for the future as well as we should,' says Aleea Devitt, a psychologist at the University of Waikato in New Zealand, who studies future thinking. And 'pessimism may be a useful 'positive' trait in some situations; there's evidence that some people can be defensive pessimists, which can actually help them better prepare for the future.' Solve the daily Crossword
Time of India
a day ago
- Health
- Time of India
What really causes obesity? Study says diet matters more than exercise
Obesity is a complex medical condition marked by excessive body fat that increases the risk of serious health problems such as heart disease, diabetes, high blood pressure, and certain cancers. While it's often believed that lack of exercise is the primary cause of obesity, a groundbreaking study published in PNAS challenges this assumption. Researchers found that people in both industrialised and developing societies burn a similar number of calories daily, regardless of how active they are. This suggests that physical inactivity may not be the main driver of the obesity epidemic. Instead, the study points to diet, particularly the overconsumption of ultra-processed foods as the leading cause. What is obesity, and its causes Obesity is a complex health condition characterized by excessive body fat. It's not merely a cosmetic issue, it's a serious medical concern that significantly raises the risk of various diseases. Obesity doesn't have a single cause. It usually results from a combination of factors, including: Genetics: Family history can predispose individuals to obesity. Hormonal and metabolic factors: Hormonal imbalances and slowed metabolism play a role. Lifestyle habits: High-calorie diets, especially rich in ultra-processed foods, are a major contributor. Physical inactivity: Although not the sole cause, sedentary lifestyles can worsen weight gain. Environmental factors: Limited access to healthy foods, poor sleep, and stress can also contribute. Medications: Certain drugs (e.g., antidepressants, corticosteroids) can lead to weight gain. 'Constrained Total Energy Expenditure' model of the study Researchers measured total energy expenditure among over 4,200 individuals across 34 countries with lifestyles ranging from hunter-gatherers to city dwellers using the gold standard 'doubly labeled water' method. Surprisingly, when adjusted for body size, daily calorie burn was almost identical regardless of lifestyle, debunking the idea that less activity equals fewer calories burned This finding supports the constrained total energy expenditure model, which suggests our bodies regulate energy use within a fixed range, even with increased activity. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Many Irish Citizens Don't Know About This Read More Undo According to lead author Herman Pontzer, overeating, especially ultra-processed foods, is nearly ten times more responsible for obesity than decreased calorie burn. Is exercising still important to manage obesity? The study does not suggest abandoning exercise. While exercise may not significantly influence weight loss on its own, it plays a crucial role in: Maintaining weight after loss Improving cardiovascular and metabolic health Enhancing mood and mental clarity Building muscle and bone strength Increasing lifespan Exercise is essential for overall well-being, but controlling calorie intake is more effective for managing obesity. Health complications of obesity Unchecked obesity can lead to life-threatening complications, including: Insulin resistance and type 2 diabetes Heart attacks and strokes Liver damage and gallbladder disease Reproductive issues and infertility Increased risk of surgical and anesthetic complications Poor mental health: depression, anxiety, low self-esteem Certain types of cancer (Breast, Colon) Also read | What causes bloating: Discover the foods and tips that help reduce bloating
Yahoo
2 days ago
- Health
- Yahoo
You Can't Outrun a Bad Diet and This Study Proves It
For years, people have blamed their expanding waistlines on not spending enough time at the gym. But a new study suggests the real problem may be what's on your plate, not how often you hit the treadmill. Scientists analyzed the daily calorie burn, body fat percentage, and BMI of more than 4,000 adults from diverse backgrounds, ranging from hunter-gatherers to office workers. Their conclusion? The amount of energy people expend each day is surprisingly similar, regardless of their lifestyle. So if we're all burning roughly the same amount of calories, why is obesity still climbing? Researchers say the answer is simple, and it's sitting in your pantry. 'We're not gaining weight because we stopped moving. We're gaining because we're overfed,' Florida neurosurgeon and longevity expert Dr. Brett Osborn, who wasn't part of the study but backs its findings, told Fox News Digital. Published in the journal Proceedings of the National Academy of Sciences, the study revealed that overeating is about 10 times more important than a lack of exercise in fueling the global obesity crisis. And while exercise is critical for heart health, mental well-being, and longevity, experts warn that counting on it to control weight isn't realistic. 'Exercise burns far fewer calories than people want to believe,' Osborn said. Adding to the problem is our growing addiction to ultraprocessed foods—calorie-packed, shelf-stable snacks engineered to override the body's natural signals of fullness. These foods make it dangerously easy to overeat, experts say, and they're driving obesity in places that never struggled with it before. Lindsay Allen, a registered dietitian, pointed out that building muscle and managing stress are also key factors in maintaining a healthy metabolism, but nothing replaces getting your diet in check. 'If you're worried about excess body fat, focus on calories in,' study authors Amanda McGrosky and Amy Luke advised. In other words, it's time to stop blaming the gym and start looking in the Can't Outrun a Bad Diet and This Study Proves It first appeared on Men's Journal on Jul 20, 2025
Medical News Today
4 days ago
- Health
- Medical News Today
For weight loss, diet may matter more than exercise
The number of people with obesity has increased rapidly over the past 30 years, and numbers are still results when energy intake from diet exceeds energy use over a prolonged trying to lose weight are advised to increase their activity levels, but a new study has found that reducing the number of calories ingested may be more important than doing more emphasizing the health benefits of regular exercise, the research suggests that cutting calories, particularly from ultra-processed foods, could be more effective in promoting weight loss. Obesity and overweight are global health concerns. The World Health Organization (WHO) states that carrying excess weight is associated with a number of health conditions, including cardiovascular diseases, diabetes, cancers, neurological disorders, chronic respiratory diseases, and digestive disorders. According to the WHO, in 2021, higher-than-optimal BMI — body mass index, a ratio of weight to height — caused an estimated 3.7 million deaths from these noncommunicable has often been said that a sedentary lifestyle may lead to obesity. However, new research in a wide range of populations suggests that excessive energy intake, rather than a lack of activity, is the main driver of weight gain.A new study, is published in PNAS, suggests that the high rates of obesity associated with economic development are most likely caused by a high calorie diet containing a large proportion of ultra-processed M. Holland MD, MS, a physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, Chicago, not involved in the study, told Medical News Today that:'This study underscores that while exercise remains vital for overall well-being, the growing obesity epidemic may be more closely tied to what, and how much, we eat. Importantly, it reveals that economic development brings with it both opportunities and risks: improved access to food, but also increased exposure to obesogenic diets.'Obesity: Is it driven by diet type or activity levels?For the 4,213 adults in their study, the researchers used two different measures of obesity — BMI and body fat percentage, which refers to the proportion of fat to total body were from 34 populations over six continents, and had a wide range of lifestyles. They included hunter-gatherers, farmers (both arable and pastoral), and people from industrialized determined three types of energy expenditure:to estimate total energy expenditure (TEE) they used the doubly labeled water methodthey measured basal energy expenditure (BEE), the amount of energy used to sustain life while at rest, also called basal metabolic rate) using indirect calorimetry or, when no measures were available, estimated it from body sizethey estimated active energy expenditure (AEE) as 0.9 (TEE) – BEE (to assume that 10% of daily calories are expended on digesting and metabolizing food).Absolute body mass, body fat percentage, and BMI were greater, and obesity was more common, in more economically developed populations. However, total energy expenditure was also greater in these explained these findings. He told us that:'On the surface, one might expect that people in more traditional lifestyles would expend more energy due to physical labor. While that holds true in absolute terms, once adjustments were made for body size, the differences in energy expenditure (especially activity energy expenditure, or AEE) were not as stark as presumed.''The key takeaway,' he continued, 'and this is a very important consideration, is that industrialized populations are not necessarily less active, they often have larger bodies that require more energy. However, they also consume more calories, particularly from highly processed and energy-dense foods. This imbalance, higher intake relative to energy needs, appears to be the more critical factor in rising obesity levels.'Processed foods encourage overconsumptionHaving compared the patterns of energy expenditure in the widely varying populations, the researchers concluded that increased energy intake is the primary factor that links overweight and obesity to economic suggest that differences in the quality and quantity of food may be key. Industrially produced foods common in developed countries may be more easily digested, reducing fecal energy loss and increasing the proportion of consumed calories that are they highlight the role of ultra-processed foods in driving obesity. These foods are energy dense, and designed to encourage overconsumption. Processing also increases the percentage of the energy consumed that can be absorbed by the their study, the percentage of ultra-processed foods in the diet was positively correlated with body fat told MNT that, 'while physical activity has undeniable health benefits, including mental and cardiovascular health, its role in weight regulation may be overstated.''The study suggests that excessive calorie intake, particularly from ultra-processed foods, which are designed to be hyper-palatable (tastier and essentially irresistible) and easy to overconsume by reducing satiety (fullness), is more strongly associated with higher body fat percentage and BMI than low levels of physical activity,' he told calorie intake, particularly from processed foods, to shift weightCommenting on the findings, Mir Ali, MD, a board-certified general surgeon, bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, not involved in the study, noted that:'If someone is trying to lose weight it is more about what they are eating than about how active they are. I do encourage my patients to exercise to preserve muscle and help burn calories, but I emphasize that if they do not eat the right foods, they will see little weight loss.'Holland advised that, 'ultimately, this study reinforces that health isn't just about 'calories in versus calories out,' but also about the quality of the calories we consume, emphasizing that what we eat may be just as important, if not more so, than how many calories we take in or burn.'He suggested that policy changes could help people lead healthier lives.'Governments can play a pivotal role in shaping food environments and public health outcomes,' said Holland. 'Policies that subsidize healthy food production (e.g., fruits, vegetables, legumes), restrict the marketing of junk food to children, and improve food labeling can help guide healthier choices. Investments in infrastructure, such as safe parks, pedestrian-friendly streets, and community centers, can also promote physical activity.''Furthermore,' he added, 'preventive health programs and equitable access to primary care are crucial for identifying and addressing obesity early, particularly in underserved populations. Public policy is a powerful lever to make the healthier choice the easier one.'
Yahoo
5 days ago
- Climate
- Yahoo
Nor'easters have become 20% more destructive in the last 80 years, scientists warn
When you buy through links on our articles, Future and its syndication partners may earn a commission. The strongest nor'easters — a type of North Atlantic storm that can produce devastating impacts along the U.S. East Coast — appear to be intensifying as the world warms, a new study finds. Researchers found that the maximum wind speeds and hourly precipitation rates of the strongest nor'easters have increased since 1940. The trends identified have "profound implications" for people living across the eastern coast of North America, given that these storms bring damaging winds, heavy snowfall and significant coastal flooding, the researchers reported in a paper published July 14 in the journal PNAS. "While there is no apparent trend in the average intensity of nor'easters, we found that the strongest nor'easters — which do the most damage and have the most impact — are indeed getting stronger," study co-author Michael Mann, a presidential distinguished professor in the Department of Earth and Environmental Science at the University of Pennsylvania, told Live Science. Nor'easters are a type of extratropical cyclone (ETC) — storms that originate outside the tropics — that form along the U.S. East Coast, particularly during late fall through early spring. These storms often cause severe damage and societal disruption because they tend to pass over densely populated regions, such as the Boston, New York and Washington, D.C. metro areas. Some of the most infamous nor'easters include the "Perfect Storm" in 1991; the "Storm of the Century" in 1993, one of the deadliest of these events on record, which claimed 208 lives; "Snowmageddon" in 2010; and the January 2018 blizzard. Related: La Niña is dead — what that means for this year's hurricanes and weather Given the potential consequences, it is crucial to understand how nor'easters are changing in response to human-caused climate change, the authors said. Yet nor'easters have traditionally received far less attention from climate researchers than tropical cyclones have. And while there is a general consensus among climate scientists that ETCs will likely decline in frequency as arctic warming decreases the temperature gradient between polar and subtropical regions, there is less agreement regarding potential changes in the future intensity of these storms. In an attempt to address some of these outstanding issues and challenges, Mann and colleagues set out to create a "virtual atlas" of nor'easters that could serve as a reliable historical database of these storms, he told Live Science. The study involved applying a cyclone-tracking algorithm to a climate dataset covering the period from 1940 to the present. Using this approach, the team identified 900 nor'easters over this period — an average of around 11 per year. The researchers then looked at trends over time, focusing on two key storm characteristics: intensity, as measured by peak sustained winds, and the average precipitation per hour. They found only a very small, statistically insignificant increase in the average intensity of all nor'easters over the study period. But among the strongest storms specifically, the authors observed a trend of increasing intensity over time — and the stronger the storm, the more pronounced that trend appeared. For the most intense nor'easters — those in the top 1% — the researchers observed an increase over the 85-year study period from peak wind speeds of around 69 mph (111 km/h) to roughly 74 mph (119 km/h). This is an increase of about 6 percent, which might seem modest — but Mann said it corresponds to a "sizable" increase of roughly 20% in the destructive potential of these storms. The trends the researchers observed regarding intensity and precipitation rates among the strongest nor'easters have likely been driven by increases in ocean temperatures and the higher capacity of a warming atmosphere to hold moisture, according to the researchers. Allison Michaelis, an assistant professor in the Department of Earth, Atmosphere, and Environment at Northern Illinois University who was not involved in the PNAS study, told Live Science that the latest research adds "important" context regarding historical nor'easter trends. "Previous studies that have examined nor'easters, or East Coast storms more generally, are more limited in scope," she said. "The most practical implication, as noted by the authors, is the potential for an increased risk of coastal flooding along the East Coast," which would directly impact people, property and infrastructure in the region. Counterintuitively, stronger nor'easters may also raise the possibility of increased winter cold-air outbreaks in inland regions along the U.S. East Coast. This is because these storms can pull cold air down from the North, as was the case in the Mid-Atlantic region with the January 2018 blizzard. RELATED STORIES —Nor'easter could drop a foot of snow on New England —Behemoth Snowstorm Watched by Satellites As It Hits US Northeast —'Bomb cyclone' set to bring blizzards and hurricane-force winds to the Northeast on Friday: Here's why. "The potential for greater likelihood of future super-nor'easters, akin to the 1993 Storm of the Century and Feb 2010 Snowmaggedon … portends prospects of paralyzing snowfalls, dangerous storm surges, and episodic cold extremes, underscoring the urgent need for coordinated efforts to assess and mitigate the devastating impacts of future such storms," the authors wrote in the paper. Edmund Chang, a professor in the School of Marine and Atmospheric Sciences at Stony Brook University who was not involved with the study, told Live Science the latest research was largely well conducted, with the data supporting the conclusions. Previous studies published by Chang and colleagues have predicted that there will be an increase in the intensity of storms close to the northeastern U.S. under warming, meaning the number of strong storms is projected to increase over that region. "The results of [the PNAS] paper are consistent with those projections, but might suggest that the proposed increase in storm intensity over this region is appearing earlier than climate models predict," Chang said.
