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It’s a common mantra: in order to live a long healthy life, you must eat well and exercise. Extra pounds are extra years off your life, we hear. Your annoying aunt might believe this with her heart and soul. But the science isn’t so sure.

Today in Nature, reporter Virginia Hughes explained that there’s a lot of research suggesting that being overweight doesn’t always mean you life a shorter life. This is what many call the obesity paradox. Hughes explains:

Being overweight increases a person’s risk of diabetes, heart disease, cancer and many other chronic illnesses. But these studies suggest that for some people — particularly those who are middle-aged or older, or already sick — a bit of extra weight is not particularly harmful, and may even be helpful. (Being so overweight as to be classed obese, however, is almost always associated with poor health outcomes.)

This paradox makes public health campaigns far trickier. If the truth was at one extreme or the other—that being overweight either was or was not good for you—it would be easy. But having a complicated set of risks and rewards doesn’t make for a good poster. And public health experts really do want most people to lose weight and not put on extra pounds.

This is where researchers, public health policymakers and campaigners are starting to butt heads. A simple message—that fat is bad—is easier to communicate. But the science just isn’t that simple.

When a researcher from the CDC put out a study that suggested that excess weight actually extended life, public health advocates fired back, organizing lectures and symposia to take down the study. Katherine Flegal, the lead researcher on that study, says she was surprised by just how loud the outcry was. “Particularly initially, there were a lot of misunderstandings and confusion about our findings, and trying to clear those up was time-consuming and somewhat difficult,” she told Hughes. But the study was a meta-review, a look at a large group of studies that investigated weight and mortality. The research is there, Flegals says, and it suggests that weight isn’t necessarily the worst thing for you. And for Flegal, what public health people do with her work isn’t really that important to her. “I work for a federal statistical agency,” she told Hughes. “Our job is not to make policy, it’s to provide accurate information to guide policy-makers and other people who are interested in these topics.” Her data, she says, are “not intended to have a message”.

And the fight against fat hasn’t really ever been particularly effective. Not a single obesity drug or diet plan has been proven to last over a year, says Hughes in a blog. And much of our weight comes down to genes, she writes:

Friedman sees things quite differently, as he eloquently explained in a 2003 commentary in Science. Each of us, he argues, has a different genetic predisposition to obesity, shaped over thousands of years of evolution by a changing and unpredictable food supply. In modern times, most people don’t have to deal with that nutritional uncertainty; we have access to as much food as we want and we take advantage of it. In this context, some individuals’ genetic make-up causes them to put on weight — perhaps because of a leptin insensitivity, say, or some other biological mechanism.

So those who are the most prone to obesity might have the least ability to do anything about it. We’re nto particularly good at understanding obesity and weight yet. Some of the key metrics that we use to study weight aren’t particularly good. Body Mass Index has long been criticized as a mechanism for understanding health. Dr. Jen Gunter blogged about Flegals’s study when it came out (she was critical of it) and explained why BMI might be the wrong tool to use to look at mortality:

BMI just looks at weight, not the proportion of weight that is muscle mass vs. fatty tissue. Many people with a normal BMI have very little muscle mass and thus are carrying around excess fat and are less healthy than their BMI suggests. There are better metrics to look at mortality risk for people who have a BMI in the 18.5-34.9 range, such as waist circumference, resting heart rate, fasting glucose, leptin levels, and even DXA scans (just to name a few). The problem is that not all these measurement tools are practical on a large-scale.

And while researchers argue over whether weight really does guarantee a shorter life and policy advocates try to figure out what to advocate, the weight loss industry rakes in billions of dollars every year playing to our fears and uncertainties.

More from Smithsonian.com:

The Culture of Obesity
Taking Childhood Obesity to Task
Mild Obesity May Not Be So Bad

Photo: NOAA

Climate change is making the world warmer and, in many places, dryer, setting the stage for increased forest fire activity across the country. In a new study, scientists with the U.S. Department of Agriculture’s Forest Service say that the amount of land affected by forest fires in the U.S. is expected to increase by at least 50 percent but maybe as much as 100 percent by 2050—a doubling of burned area within less than 40 years.

In the study, led by meteorologist Yongqianq Liu, the researchers say that, more than just responding to a warming world, forest fires actually stoke themselves over the long term. By releasing carbon dioxide to the atmosphere, forest fires increase the likelihood of future fires. According to earlier research forest fires account for about a third of global carbon dioxide emissions. Some of this carbon dioxide will eventually get pulled back out of the atmosphere by plants regrowing in the burned region. But in the short term, say the scientists, the carbon dioxide is an important part of the amplified greenhouse effect.

According to the study, smoke streaming from fires can actually make the area under the cloud colder, because smoke in the air reflects sunlight. That might seem like a silver lining to the ash cloud. But the smoke also suppresses rain, increasing the potential for drought. So, really, it’s not much of a silver lining after all.

In the end, the scientists say that climate change is going to make forest fires worse, and it seems that the fires themselves will encourage this trend.

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Fires Are Escaping Our Ability to Predict Their Behavior
Watch Out: This Year’s Fire Season Will Be Another Bad One for the West

Photo: Timmarec

In Croatia, scientists are working on a new way to detect land mines without risking lives, reports the Associated Press. Honeybees, the scientists say, have an incredible sense of smell, and with the right amount of prodding can be trained to sniff out TNT, the most common explosive used in land mines. In preliminary testing:

Several feeding points were set up on the ground around the tent, but only a few have TNT particles in them. The method of training the bees by authenticating the scent of explosives with the food they eat appears to work: bees gather mainly at the pots containing a sugar solution mixed with TNT, and not the ones that have a different smell.

A common technique in animal behavior training, the bees are taught to associate the smell of TNT with food. Once that association is firm, the bees can be turned loose in search of mines.

”It is not a problem for a bee to learn the smell of an explosive, which it can then search,” Kezic said. “You can train a bee, but training their colony of thousands becomes a problem.”

Bees, with their incredible sense of smell, light weight and ability to fly should be better candidates for mine hunting than other approaches. Mine decommissioning teams already use dogs and rats to hunt down mines. But, some anti-personnel mines are so sensitive that the weight of a pup can set them off. The bees’ training is still underway, says the AP, but if and when they’re ready the Croatian-trained bees will be able to flit from mine to mine without setting them off.

From 1999 to 2008, says the Guardian, 73,576 people reportedly died to hidden land mines or unexploded munitions. “Of these, around 18,000 were confirmed deaths – 71% of victims were civilians and 32% were children.” Aside from their destructive potential, land mines are also a psychological and social plight.

Landmines and cluster munitions have been described as “weapons of social cataclysm”, which perpetuate poverty and prevent development. They leave a legacy of indiscriminate civilian injuries and deaths, burden struggling healthcare systems and render vast tracts of land uninhabitable and unproductive. As Kate Wiggans, from the International Campaign to Ban Landmines and Cluster Munition Coalition (ICBL-CMC) says: “They keep poor people poor, decades after conflict.”

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Designer Creates Wind-Powered Land Mine Detonator

Photo: Dennis Skley

“Dying of a broken heart” is more than just a turn of phrase. The despair of losing a loved one—the stress and the anxiety and the pumping adrenaline—can actually kill you. Writing for The Conversation, cardiologist Alexander Lyon tells the tale of the broken-hearted, those whose hearts simply shut down during times of stress.

Known to doctors as Takotsubo cardiomyopathy, broken heart syndrome is a special type of heart attack. In a normal heart attack, a blocked artery chokes the flow of blood to the heart, cutting off the supply of oxygen and killing heart tissues. In a Takotsubo heart attack, there is no such blockage. For the broken-hearted, nine out of ten of whom are “middle-aged or elderly women,” says Lyon:

They have chest pains, a shortness of breath and ECG monitors show the same extreme changes which we see with a heart attack.

But when an angiogram is performed, none of their coronary arteries are blocked. Instead, the lower half of their ventricle, the main pumping chamber of their heart, shows a very peculiar and distinctive abnormality – it fails to contract, and appears partially or completely paralysed.

…In the most extreme cases the heart can stop – a cardiac arrest.

We’re still not really sure what causes broken heart syndrome, writes Lyon, but research suggests that adrenaline—the hormone behind the body’s “fight or flight” response—may be to blame.

At low and medium levels adrenaline is a stimulating hormone, triggering the heart to beat harder and faster, which we need during exercise or stress. However at the highest levels it has the opposite effect and can reduce the power the heart has to beat and triggering temporary heart muscle paralysis.

Unlike normal heart attacks, where the tissues are usually damaged for good, people can often walk away from a Takotsubo heart attack unscathed. But though the physical damage may be undone, a broken heart never truly mends.

More from Smithsonian.com:

Heart Attacks May Be Linked to Air Pollution
Ancient Egyptian Princess Had Coronary Heart Disease

Timmins, Ontario, has a long history as a mining town. Photo: Michael Jacobs

In the small city of Timmins, Ontario, a town nestled half way between Michigan and Hudson Bay, there is a mine. Actually, there are many mines—it’s a mining town. But this story is about just one, a mile and a half deep, where there is water bubbling up from below that has been cut off from the rest of the world for at least a billion years—maybe as much as 2.6 billion years.

The longer end of that timeline, Ivan Semeniuk points out in the Globe and Mail, is about half the age of the Earth. This water hasn’t been in contact with the rest of the planet since before the rise of multicellular life.

But like the water trapped in frozen lakes below Antarctica’s massive ice sheets, researchers suspect there might be life in these flows.

“It’s been called the Galapagos of the subsurface,” says Barbara Sherwood Lollar to New Scientist. The water, “is packed with hydrogen and methane – chemicals that microbes love to eat.”

“What we have here,” says Sherwood Lollar, a microbiologist at the University of Toronto in Canada, “is a plate of jelly donuts.” While she has yet to confirm whether the water is inhabited, she says the conditions are perfect for life.

The scientists don’t know whether there is any life in the ancient, isolated water. But they’re working on it. The water is young enough that it would have been locked away after life arose on Earth. But it’s been trapped for so long that any life that does exist would likely be unique—a relic of an ancient world. The CBC:

Some Canadian members of the team are currently testing the water to see if it contains microbial life — if they exist, those microbes may have been isolated from the sun and the Earth’s surface for billions of years and may reveal how microbes evolve in isolation.

One can’t help but be reminded of the Balrog: “Moria! Moria! Wonder of the Northern world. Too deep we delved there, and woke the nameless fear.”

More from Smithsonian.com:

First Signs of Life Found in Antarctica’s Subglacial Lakes