Fat's surprising role in aging and longevity

Yahoo

03-04-2025

We tend to think of fat as nothing more than extra baggage, something that slows us down, makes our jeans fit tighter and, if we're being honest, messes with our confidence in the gym and bedroom.
At most, we acknowledge that extra weight contributes to heart disease, diabetes, and other health issues, but we take comfort in our plans to lose it 'someday.'
The problem is that as we age, "someday" moves further to the horizon and what worked when we were younger—a week on Whole 30 and incline treadmill workouts—doesn't cut it anymore.
Metabolisms slow, poor eating habits set in, and many of us give in to the idea that weight gain is an inevitable part of aging.
That's a dangerous mindset. Obesity is more than just the passive storage of excess calories or a vague future threat. It's an active, disruptive force that speeds up aging, making us biologically older than our years.
Scientists are zeroing in on how excess fat, especially visceral fat stored around our organs, fuels chronic inflammation, disrupts metabolism, weakens the immune system, and accelerates cognitive decline.
While scientists are investigating all manner of longevity boosters, here's the truth: When it comes to slowing aging and extending lifespan, few interventions are as well-supported by science as fat loss, Hone Health reports.
Most people assume fat is just sitting there, an inert, gelatinous mass waiting to be burned off. But fat is far from passive—it's actually the body's largest endocrine organ, playing a central role in metabolism.
Adipose tissue produces key metabolic hormones, including leptin, adiponectin, and resistin, which regulate everything from hunger to insulin sensitivity. But fat also acts as a hormone factory, containing the enzyme aromatase, which converts testosterone into estrogen.
This process becomes a problem when fat accumulates—especially around the belly. In men, excess body fat increases aromatase activity, raising estrogen levels while lowering testosterone, which can slow metabolism, promote fat storage, and reduce muscle mass, creating a cycle of further weight gain.
In postmenopausal women, fat becomes the primary site for estrogen production as ovarian estrogen production declines. While some estrogen is necessary, too much can lead to increased fat storage, insulin resistance, and a higher risk of metabolic disorders.
As fat levels increase, hormonal imbalances intensify. Excess adipose tissue boosts estrogen production, which further encourages fat storage, creating a cycle that makes weight loss increasingly difficult.
And the damage isn't just hormonal. Over time, excess fat releases inflammatory chemicals called cytokines, triggering chronic, low-grade inflammation—a silent force accelerating aging from the inside out.
Scientists call this process inflammaging, and it's a major factor linking obesity to nearly every age-related disease, from heart disease to Type 2 diabetes to Alzheimer's.
The longer your body is stuck in a state of inflammation, the faster it breaks down, says Christian Sell, Ph.D., a professor in the Department of Biochemistry and Molecular Biology at Drexel University College of Medicine in Philadelphia.
Sell and Antonello Lorenzini, Ph.D., an associate professor in the Department of Biomedical and Neuromotor Sciences at the University of Bologna, Italy, study the intersection of obesity and aging. Their published research shows that excess fat increases oxidative stress, damages cells, and prematurely ages them.
"This is critical for all types of cells," Sell explains, "including endothelial cells, which line blood vessels and regulate oxygen and nutrient delivery; fibroblasts, which support skin structure and repair to prevent premature aging; and astrocytes and neurons, which are essential for maintaining brain function and cognitive health."
One of the biggest myths about fat loss is that it's purely about aesthetics. Sure, dropping a few pounds makes you look better and feel lighter, but it's about more than vanity. Fat loss preserves your body's ability to function at a high level for as long as possible.
Take stem cells, for example. These are the body's built-in repair mechanisms, responsible for regenerating tissues, healing wounds, and maintaining muscle mass. But both aging and obesity weaken stem cells, making recovery from illness and workouts slower, while increasing disease risk.
Excess fat also flips the body's metabolic switch in the wrong direction. When you carry too much weight, the mTOR and IIS pathways—cellular processes that speed up aging—go into overdrive.
An overabundance of nutrients caused by overeating pushes cells to divide even when they shouldn't, increasing oxidative stress (damage caused by toxic byproducts of metabolism) and the risk of disease.
Meanwhile, longevity-promoting pathways like AMPK and sirtuins—critical for fat-burning and cellular repair—get suppressed.
The combined effect is like driving a car with your foot jammed on the gas while your brakes are failing. Eventually, you'll end up wrapped around a metaphorical telephone pole.
The most surprising consequence of obesity-related aging, according to Sell? How it wears on our blood vessels.
"I think people would be shocked to learn how damaging carrying extra weight is on the blood vessels, especially those supplying the brain," he says.
Over time, he explained, reduced blood flow due to damaged vessels can deprive brain cells of oxygen and essential nutrients, leading not just to a loss of mental sharpness, but an increased risk for neurodegenerative diseases like Alzheimer's and vascular dementia.
The good news? Fat-related aging isn't necessarily permanent if you lose the weight.
Sell likens losing weight to quitting smoking: There may be some lasting damage, but you can largely reverse it while limiting its impact on longevity.
Research suggests intermittent and periodic fasting, combined with proper nutrition, is one of the most effective ways to slow aging and even reverse some of the cellular damage caused by obesity.
One of the best-documented methods for extending lifespan in animal studies is caloric restriction (CR), a substantial, sustained reduction in calorie intake that still maintains proper nutrition.
In lab studies, rodents placed on a CR diet lived significantly longer than their overweight counterparts, with fewer age-related diseases and improved metabolic function.
And while humans aren't mice, research has shown that moderate caloric restriction—typically a 10% to 30% reduction in daily calorie intake—lowers inflammation, improves insulin sensitivity, and enhances metabolic health.
Studies like CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy), conducted by the National Institute on Aging, suggest controlled calorie reduction activates longevity pathways.
It can also reduce biological markers of aging such as blood pressure, cholesterol, C-reactive protein, insulin growth factor, and more.
But most of us aren't going to eat 30% fewer calories for the rest of our lives. The good news? We don't have to.
Even modest weight loss delivers significant benefits. Research shows that losing just 5% to 10% of body weight can lower inflammation, improve cardiovascular health, and reduce the risk of metabolic diseases, all of which contribute to a longer, healthier life.
Research from the Yale School of Medicine indicates that a modest weight reduction of about 10% can lead to a reduction of liver fat and a reversal of liver insulin resistance and type 2 diabetes. This suggests that even a 10% weight reduction can significantly improve insulin sensitivity and reduce the risk of type 2 diabetes.
More sustainable strategies, like intermittent fasting, time-restricted eating, strength training, and prioritizing nutrient-dense foods, can mimic many of the same anti-aging benefits without extreme calorie cutting, say experts.
If you want to keep your body young and strong, you don't need to starve yourself. The key is changing how your body burns energy, not just eating less.
One way to do this is through strategic fasting. Research shows that intermittent fasting, or simply extending the time between your last meal at night and your first meal the next day, can activate the same longevity pathways as calorie restriction.
By giving your body a break from constant digestion, you shift into fat-burning and repair mode, where your body naturally clears out damaged cells and regenerates new ones, says Sell.
"The research on intermittent fasting is extremely interesting," says Lorenzini. "It forces us to consider not only how many calories we take in, but when."
While there's still much to learn, he recommends intermittent fasting as a promising strategy for weight loss and longevity. Just be careful not to take fasting too far. While short-term fasting ( less than 24 hours) generally increases metabolism and burns more fat, fasting for more than 24 hours tends to lower metabolism.
Another critical piece? Muscle. Strength training isn't just for bodybuilders, it's one of the best ways to fight obesity-related aging.
Muscle is metabolically active tissue, meaning the more of it you have, the more energy you burn at rest. And since muscle mass naturally declines with age, lifting weights is one of the most powerful tools you have to fight back.
Research suggests that engaging in strength training at least two to three times per week is enough to preserve and build muscle, improve metabolic health, and slow down age-related muscle loss.
The sweet spot for longevity benefits appears to be 8 to 12 reps per set at moderate to high intensity (about 60% to 80% of your one-rep max), targeting all major muscle groups.
Studies have also found that progressive overload—gradually increasing weight or resistance over time—is key to maintaining long-term strength gains and ensuring continued metabolic benefits.
But structured workouts aren't the only way to improve metabolic health.
Non-Exercise Activity Thermogenesis (NEAT)—all the movement we do outside of intentional exercise, like fidgeting, standing, or walking—plays a surprisingly big role in fat metabolism. Research from the Mayo Clinic dating all the way back to 1999 found that NEAT was the strongest predictor of resistance to weight gain when participants were overfed, accounting for two-thirds of the excess calories burned.
And then there's nutrition. Not just how much you eat, but what you eat. For example, cutting out ultra-processed foods and refined sugars can lower chronic inflammation and prevent fat-driven aging, according to 2024 research in the American Journal of Clinical Nutrition.
Meanwhile, prioritizing protein, fiber, and healthy fats keeps metabolism humming and preserves lean muscle.
"It's important to note," Sell adds, "that extreme caloric restriction is not advised. A balanced approach incorporating exercise and a healthy diet will provide the best results."
Lastly, don't discount the new class of weight-loss medications like Ozempic and Wegovy (semaglutide).
"GLP-1 agonists represent a qualitative leap," Lorenzini says. "Obesity is a pathology, and if we cannot solve the problem with lifestyle changes. For many, these weight loss medications are a useful resource that shouldn't be demonized."
Aging is inevitable, but the speed at which you age is somewhat within your control. About 10% to 20% of your lifespan is likely dependent on factors you can control, Sell says, while Lorenzini puts it around 25%
More importantly, you do control how well you live your life as you age. A reasonable diet and exercise program will provide increased function into old age, which is arguably more important than just adding years.
By making small, sustainable changes to how you eat, move, and recover, you can slow down aging, preserve your muscle mass, and keep your body performing at its peak for years to come.
"I think change is best achieved in small steps because small steps become habits," says Lorenzini. "Committing to eating those extra servings of fruit and vegetables and walking even 10 minutes a day are non-radical changes that can be implemented without much effort and so it's easier to turn them into habits," Lorenzini says.
"Once these habits are under the control of our 'autopilot,' the effort becomes zero, and we are ready for the next small change. That's what I do myself."
As for Sell? He is motivated to stay in shape by his lifelong love of road cycling. "I want to ride for as long as I can," he said.
Because in the end, the goal isn't just to live longer, it's to live better.
This story was produced by Hone Health and reviewed and distributed by Stacker.