Extraordinairy Photos of Ordinary People

Saturday, January 17th, 2015

Artsy photographer Benjamin Von Wong brought along his expensive lighting equipment and a rain machine and took extraordinairy photos of ordinary people:

Mental Fatigue

Thursday, January 15th, 2015

Mental fatigue leads to physical fatigue, so mental training can improve physical performance:

In the twelve-week study, two groups of fourteen soldiers each trained on stationary bikes. The first half trained three times a week for one hour at a moderate aerobic pace. The second half did exactly the same intensity of training for the same duration, so the physiological work was the same. But while this second group pedaled, they were also doing a mentally fatiguing task.

The results at the end of the study were mind blowing. The two groups saw similar increases in their VO2 max, meaning the physiological effects of the training were about the same. But when you asked them to do what’s called a “time to exhaustion test, in which they rode at a specific percentage of their VO2 max until they couldn’t go on, the differences were profound. The control group saw the time to exhaustion improve 42 percent from their results before the training started. The group that combined training with mental exercise saw an improvement of 115 percent, almost three times the improvement that the control group saw. Combining the physical and mental stress led to a quantum leap in performance.

From Faster, Higher, Stronger, by Mark McClusky.


Monday, January 12th, 2015

As we get older, our immune systems begin to malfunction, leading to inflammaging:

This condition is characterized by increased production of inflammatory cytokines, as well as lower immune function. Cortisol is produced to counteract the inflammation, and this has deleterious consequences as well.

Inflammaging and sarcopenia — loss of muscle mass — are closely linked:

It turns out that a number of things can be done to counteract sarcopenia. A recent study found, for instance, that old rats given ibuprofen had their anabolic resistance abolished, and restored their muscle mass to levels seen in younger rats. Their levels of muscle protein synthesis rose by 25%. The authors of the study make clear the connection between inflammation and anabolic resistance, noting that “inflammatory markers and cytokines levels were significantly improved in treated old rats”.

That may all be well and good, but does this work in humans? In Influence of acetaminophen and ibuprofen on skeletal muscle adaptations to resistance exercise in older adults, the researchers put older adults (mid sixties) on a resistance training program, and gave two groups of them either acetaminophen or ibuprofen. What happened next will shock you: those on the anti-inflammatory drugs gained more muscle and more strength than controls.

That did in fact shock me, because I’d read previously that anti-inflammatories reduced or eliminated the body’s response to resistance training — no pain, no gain.

In Faster, Higher, Stronger, Mark McClusky has more to say about NSAIDs:

Athletes love these drugs. A study of players in the 2002 and 2006 soccer World Cup found that more than half of them took an NSAID during the tournament. Ten percent of players overall were taking them before every match — on one squad, twenty-two of the twenty-three players were doing so. In endurance sports, ibuprofen use is so prevalent — up to half of competitors in one popular ultramarathon race took ibuprofen during the run — that it’s often known as “vitamin I.”

There are a couple of problems with this type of widespread use. The first is that taking ibuprofen before an event doesn’t help with performance. In fact, there have been studies that have shown that cyclists perform about 4.2 percent worse in a ten-mile time trial when they’ve taken ibuprofen before the effort as compared to a placebo. Furthermore, animal studies have shown that taking ibuprofen during training can lead to a reduction in the benefits you get from it — even if you increase your training volume, you don’t get the same results as you would without the ibuprofen. Ibuprofen seems to, paradoxically, increase the amount of inflammation seen in the body during exercise. And then there are the problems that chronic ibuprofen use can cause with the liver and gastrointestinal system.


Acetaminophen might be a different story, however. First of all, the drug operates differently than ibuprofen and other NSAIDs. It isn’t a strong anti-inflammatory, so it doesn’t have the same negative effects on training adaptation that ibuprofen does. More interesting, however, are the possible effects that acetaminophen might have if you take it before you exercise.

A study at the University of Exeter took a group of thirteen well-trained cyclists, gave them either a placebo or 1,500 mg of acetaminophen, and asked them to ride a ten-mile time trial. After taking the drug, riders were 2 percent faster than those who had gotten the placebo. But that’s not all. When the riders had taken acetaminophen, they rode at a higher heart rate and produced more lactate, but had the same perception of effort as when they took the placebo. That’s to say, the rode harder, but it didn’t feel like it.

The lab, led by Alexis Mauger, has gone on to show that acetaminophen also provided a group of recreational cyclists with an increase in sprint performance on the order of 5 percent, mostly because repeated sprints didn’t suffer as large a drop in performance as without the drug. And they have also shown that acetaminophen increases performance in hot (86 degrees Fahrenheit) conditions, by helping keep the riders’ core temperatures lower due to the drug’s antipyretic effects. The riders didn’t just feel cooler as they exercised; their bodies actually stayed cooler during the effort.

Winter Never Comes

Thursday, January 8th, 2015

The Metabolic Winter hypothesis suggests that obesity is partly due to lack of exercise, but mostly due to chronic overnutrition and chronic warmth:

Seven million years of human evolution were dominated by two challenges: food scarcity and cold. “In the last 0.9 inches of our evolutionary mile,” they write, pointing to the fundamental lifestyle changes brought about by refrigeration and modern transportation, “we solved them both.” Other species don’t exhibit nearly as much obesity and chronic disease as we warm, overfed humans and our pets do. “Maybe our problem,” they continue, “is that winter never comes.”

Not a bit of him’s scraggly or scrawny

Sunday, January 4th, 2015

There’s no man in town half as manly as Gaston:

Why Do Human Children Stay Small For So Long?

Thursday, December 18th, 2014

Why does it take so long for human children to grow up?

A male chimp and male human, for example, both end up with the same body weight but they grow very differently: at year one the human weighs twice that of the chimp but at eight the chimp is twice that of the human. The chimp then gains its adult weight by 12 — six years before the human. A male gorilla is also a faster growing primate — a 330-pound male gorilla weighs 110 pounds by its fifth birthday and 265 pounds by its tenth.

Clues to the answer can be found in the young human brain’s need for energy. Radioactive tracers allow scientists to measure the glucose used in different areas of the brain but this procedure is only used rarely when it is justified by investigating neurological problems. However, the few cases we do have reveal how radically different the childhood brain is from that in adults or infants.

From about the age of four to puberty, the young brain guzzles glucose — the cerebral cortex, its largest part, uses nearly (or more than) double that used earlier or later in life. This creates a problem. A child’s body is a third of the size of an adult but its brain is nearly adult-sized. Calculated as a share, a child’s takes up half of all the energy used by a child.

Map child growth against what is known about brain energy consumption and they shadow in a negative way: one goes up, the other down. The period in which the brain’s need for glucose peaks happens just when body growth most slows. Why? In a recent study in the Proceedings of the National Academy of Sciences, I proposed that this prevents a potential conflict over blood glucose that might otherwise arise between brawn and brain.

A young child has at any moment a limited amount of glucose in its blood circulation (3.4g — the equivalent in weight to about three Smartie candies). Fortunately a child’s liver can quickly generate glucose, providing other organs do not compete against the brain for the glucose. But as French child exercise physiologist Paul Delamarche noted:

Even at rest, it would appear to be difficult for children to maintain blood glucose concentration at a steady level; an immaturity of their gluco-regulatory system would seem to be likely, therefore causing a delay in an adequate response to any stimulus to hypoglycemia like prolonged exercise.

Organs elsewhere in the body fuel themselves with energy sources that do not compete with the brain such as fatty acids. But skeletal muscle can compete when exertion is intense and sustained.

In adults, the liver quickly ramps up its generation of glucose so even active brawn does not usually compete against the brain. But conflict can arise even in adults, and it could pose a real threat to children. Luckily they do not let it happen: they stop exertion if it gets intense and sustained. Not that this makes children inactive — they do even more low and moderate exercise than adolescents and adults.

So putting a break on growth in childhood aids limiting skeletal muscle as a potential glucose competitor to the brain. And not only are their bodies smaller but they contain (as a percentage of their bodies) less skeletal muscle than in adults. And even that skeletal muscle, some research suggests, is of a type that uses less glucose than in active adults.

So human growth rate negatively shadows increased energy use in the child’s brain.

Kettlebell Lessons with a Firearms Instructor

Friday, December 5th, 2014

While perusing Pavel’s fitness site, I was surprised to come across this story from a firearms instructor:

To illustrate the importance of dry fire, consider the story of Dave Westerhout.  Mr. Westerhout is known as one of the founders of the International Practical Shooting Confederation (IPSC) and a trainer for the Rhodesia Defense Force.  In the late 70’s, ammunition was particularly scarce in the African nation of Rhodesia.  This ammunition shortage was due in large part to how unpopular Rhodesia was politically. The native African population was disenfranchised and Rhodesia was breaking away from the British Empire.  Other nations weren’t recognizing them as a nation and multiple trade sanctions were imposed.  One side effect of these sanctions was an extreme ammunition shortage.

Westerhout adapted to the severe ammunition shortage the only way he knew how: dry fire practice.  He conducted experiments with two groups of soldiers.  One would use live fire, the other dry fire.  The results were impressive.  The dry fire group was outscoring the live fire group!  This convinced the leadership to adopt the dry fire practice for the entire force.

Then, in 1977 at the first World Practical Pistol Championship, the Rhodesian team produced some astounding results.  Dave Westerhout took the first place and another Rhodesian took the second, the Rhodesian team won the overall team event!

An American took the third place. All of this happened when the US was considered the dominant force in competitive shooting. All of this happened while Rhodesia faced an ammo shortage. How is this possible? Lots of dry fire!

The advantages of dry fire are obvious. You can do it in your home very quickly and easily. You are not driving somewhere and spending money on range time or ammo. You are getting a LOT of repetition and working on the most difficult of all fundamentals — the trigger control. Anyone can squeeze a trigger. Anyone can align the sights. Can you maintain sight alignment through a smooth yet quick trigger squeeze? If not, DRY FIRE! Start with what takes the least time and costs the least money. Add complexity later!

Now, it should be noted: Dry fire practice does NOT fully replace live fire training. It is just a great supplemental training tool. There are certain fundamentals you just can’t practice without sending rounds down range. For starters, you can’t practice Recoil Management. This stands to reason, as it’s hard to practice managing a gun’s recoil w/out feeling it recoil in your hands. Secondly, you can’t practice the Follow Through. In this instance, that simply means you can’t get a feel for how quickly you can get the gun back on target and send additional rounds down range (should it be necessary). All of that aside, you can practice the most difficult fundamental with dry fire training: the Trigger Control.

Another similarity I noticed is that Frequency Trumps Duration.

Are you training only once in awhile for a long dragged out session that leaves you wiped out? Or are you training more frequently for shorter periods leaving you “stronger or better” than when you started?

The Cost of Adaptation

Thursday, December 4th, 2014

Pavel Tsatsouline revisits the cost of adaptation:

According to Prof. Bayevsky, at any given moment, between 50 to 80% of all people are in the so-called donozoological state, or between health and illness. According to Academician Nikolay Amosov, these people are only “statically healthy” — until the environment disrupts their fragile status quo. Although they may be feeling fine, even a mild infection is potentially dangerous to them. Not the infection itself, but the complications from the strain it puts on the supply systems. You might know someone who died of a cardiac arrest while struggling with some other malady.

Say, Bob’s tissues need a gallon of blood a minute at rest and his heart can pump out 1,3 gallons per minute max, which is average — this is called the maximal cardiac output. Everything is fine and dandy — until the man goes to South America and catches typhoid fever. His energy requirements skyrocket, fighting a disease is not unlike performing hard labor. Typhoid fever doubles one’s oxygen consumption. The heart now has to pump two gallons of blood per minute. Except… its limit is only a gallon and a half. Bingo. The traveler returns home in the jet’s cargo bay in a body bag. The man died from failure of systems that were not even stricken by the disease. Had Bob cared to work on increasing their functional reserves, he would have survived.

Academician Amosov coined the term “the quantity of health”, or the sum of the reserve powers of the main functional systems. These reserve powers are measured with the health reserve coefficient, the ratio of the system’s maximal ability to the everyday demands on it.


Obviously, to improve your quantity of health, you need to increase the reserves of your functional systems, cardiovascular, pulmonary, muscular, etc. There are over a hundred measurable health parameters. Individual adaptation has been defined as gradual development of resistance to a particular environmental stimulus that enables the organism to function in conditions earlier incompatible with life and meet challenges that previously could not be met (1). In other words, adaptation is about survival.

The path to health seems simple: train hard, increase your “quantity of health”, and live happily ever after. If Bob built up to the point of being able to swim non-stop for an hour a day, surely he would have built enough heart capacity to survive typhoid fever! Certainly — while making himself more vulnerable to other stressors…

A number of Soviet and Russian textbooks, from the 1970s until today, cite a study of young rodents undergoing an intense swimming regimen — one hour a day for ten weeks (2). Their heart mass increased — while the mass of their kidneys and adrenal glands went noticeably down, and so did the number of the liver cells. In other words, while the training increased the functional capacity of the heart, it simultaneously reduced the capacity of several inner organs! If later the “athletes” from the study encountered significant physical loads, they would be better prepared to handle them and survive compared to their untrained peers. If, on the other hand, the challenge were directed at the liver or kidneys (through a change of food, an increase of sodium intake, etc.), the hard training rats would be at a disadvantage compared to their lazy brothers and sisters…

This phenomenon is called “the cost of adaptation” (3). The cost can be exacted from the systems of the body directly loaded by the stressor — or from other system(s) not directly involved in dealing with the stressor (4).


If you choose health, do not reach for Olympic medals, avoid narrow specialization, and train in moderation. Because high adaptation cost is experienced especially by specialist athletes and people who perform hard physical labor (6).

Soviet research teaches us that sport training and physical culture lead to a significant decrease in diseases overall and injuries (7). Renown Soviet scientist Prof. Zimkin concluded, “It has been determined from animal experiments and observation of human subjects that muscular activity increases the organism’s non-specific resistance to many unfavorable stressors people are subjected to in modern conditions, e.g. hypoxia, some poisons, radioactive materials, infections, overheating, overcooling, etc. A significant decrease in illnesses has been observed in people training for sport or practicing physical culture.” He went on to add that “rational” training is what is needed to deliver such resilience (8). Moderate physical loads stimulate the immune system (9).

(Hat tip to Mangan.)

Sleep Extension

Wednesday, November 12th, 2014

Sleep deprivation has substantial effects on mood, mental and cognitive skills, and motor abilities, and this certainly applies to athletes:

It seems like certain kinds of athletic tasks are more affected by sleep deprivation. Although one-off efforts and high-intensity exercise see an impact, sustained efforts and aerobic work seem to suffer an even larger setback. Gross motor skills are relatively unaffected, while athletes in events requiring fast reaction times have a particularly hard time when they get less sleep.

Until recently, no one had studied the opposite of sleep deprivation, sleep extension:

The Cardinal men’s basketball team volunteered to be Mah’s study cohort. Eleven players used motion-sensing wristbands to determine how long they slept on average—just over 6.5 hours a night. For two weeks, the team kept to their normal schedules, while Mah’s researchers measured their performances on sprint drills, free throws, and three-point shooting. Then, the players were told to try and sleep as much as they could for five to seven weeks, with a goal of 10 hours in bed each night. Their actual time asleep, as measured by the sensors attached to their wrists, went from an average of 6.5 hours to nearly 8.5 hours.

The results were startling. By the end of the extra-sleep period, players had improved their free throw shooting by 11.4 percent and their three-point shooting by 13.7 percent. There was an improvement of 0.7 seconds on the 282-foot sprint drill—every single player on the team was quicker than before the study had started.

A 13-percent performance enhancement is the sort of gain that one associates with drugs or years of training—not simply making sure to get tons of sleep.

Professional athletes have to travel, and they often have to travel across time zones. Over the season, they appear to get fatigued and make certain kinds of errors more often:

Researchers at Vanderbilt University examined the plate discipline of hitters in baseball over the course of the season, and found that hitters swing at more pitches outside the strike zone late in the season than they do earlier in the season. Why? Dr. Scott Kutscher, the leader of the research team, said in a press release, “We theorize that this decline is tied to fatigue that develops over the course of the season due to a combination of frequency of travel and paucity of days off.”

Kutscher’s team has found that this decay in plate discipline has become more pronounced in baseball since 2006—the year that Major League Baseball banned stimulants. (For years, bowls of amphetamines, known as “greenies,” were a fixture in baseball clubhouses.)

Whoa, whoa, whoa. The “greenies” popular in the 1960s were just banned eight years ago? Wow.

You can be fooled in a thousand subtle ways

Wednesday, October 8th, 2014

I didn’t realize how Gary Taubes came to write Good Calories, Bad Calories:

He majored in applied physics at Harvard, where he also played on the football team’s defensive line. (John Tuke, one of his teammates, recalls that Taubes stood out for his intensity.) After Harvard, Taubes headed to Stanford for a master’s in engineering with visions of becoming an astronaut. It was only after realizing that NASA wasn’t likely to send a man of his size to space—Taubes is 6?2? and 220 pounds—that he decided to pursue an interest in investigative reporting that had been sparked by reading All the President’s Men.

He attended Columbia University’s Graduate School of Journalism and soon landed a job at Discover magazine. He caught a break in 1984, when a profile of particle physicist Carlo Rubbia led to a deal for his first book, Nobel Dreams. Taubes thought he would be documenting a breakthrough in physics. Instead, the book chronicled Rubbia’s errors and the machinations he used to outmaneuver his fellow physicists. Taubes was struck that science could be so subjective at the highest levels—that it’s not just the big mistakes that scientists have to worry about but the numerous small ones that accumulate to support their misconceptions. “You can be fooled in a thousand subtle ways,” he says.

That lesson stuck with him when, almost by accident, he turned his attention to nutrition science in 1997. By then a freelancer and running low on rent money, he called his editor at Science and asked if there were any assignments he could turn around quickly. The editor mentioned a paper in The New England Journal of Medicine that detailed a dietary approach to reducing blood pressure without restricting salt. Maybe he could write about that?

Taubes knew almost nothing about the topic. He would end up spending the next nine months interviewing 80 researchers, clinicians, and administrators. That research resulted in an August 1998 article headlined “The (Political) Science of Salt.” It was a sweeping takedown of everything scientists thought they had established about the link between salt consumption and blood pressure. The belief that too much salt was the cause of hypertension wasn’t based on careful experiments, Taubes wrote, but primarily on observations of the diets of populations with less hypertension. The scientists and health professionals railing against salt didn’t seem to notice or care that the diets of those populations might differ in a dozen ways from the diets of populations with more hypertension.

Taubes began to wonder if his critique applied beyond salt, to the rest of nutrition science. After all, one of the researchers Taubes interviewed had taken credit not only for getting Americans to eat less salt but also for getting them to eat less fat and eggs. He kicked off a multiyear research project that culminated in 2002, when he published a New York Times Magazine cover story on fat that would vault him into prominence and onto the path to NuSI.

Under the cover line “What if Fat Doesn’t Make You Fat?” Taubes made the case that we get fat not because we ignore the advice of the medical establishment but because we follow it. He argued that carbohydrates, not fat, were more likely to be the cause of the obesity epidemic. The piece was a sensation.

CrossFit Preschool

Saturday, October 4th, 2014

CrossFit gyms are now offering preschool programs:

In preschool CrossFit, dangling off hanging bars is likened to being a monkey. Squats are frog-inspired. Box jumps, plyometric leaps long beloved by elite athletes, are smaller and rebranded for kids as superhero leaps.

In Long Island City, a tunnel constructed from red tumbling mats inspired comparisons to snakes and worms. Games and exercises were punctuated by water breaks and doodling. CrossFit Kids instructors are discouraged from telling children to lift weights or move faster, Martin said. High-fives for effort are prevalent.


For some parents and children, CrossFit has become an alternative to the travel teams and year-round youth sports schedules that can be so demanding.

Savory-Flavored Carbs and Fat

Tuesday, August 12th, 2014

The main driver of the obesity epidemic has been increased intake, rather than decreased energy expenditure, Stephen J. Simpson and David Raubenheimer say:

The obesity problem is best understood not as the result of the overconsumption of a single macronutrient, but from a skewing of the proportion of each macronutrient in our diet — notably the dwindling quantity of protein in processed food products. The paucity of protein relative to fats and carbohydrates in processed foods drives the overconsumption of total energy as our bodies seek to maintain a target level of protein intake.


Many processed food products are protein-poor but are engineered to taste like protein. Many people therefore eat far too much fat and carbohydrate in their attempt to ingest enough protein. In this way, engineered foods subvert the appetite control systems that should be helping to balance the consumption of macronutrients. The results are striking. In the United States, the typical diet saw a 0.8% decline in protein concentration between 1971 and 2006. During this same period, the consumption of calories from carbohydrates and fats increased by 8%, a trend reflected in the rising prevalence of obesity, but protein intake remained almost unchanged.

The substitution of carbohydrates and fats for protein is driven by economics. Food manufacturers have a financial incentive to replace protein with cheaper forms of calories, and to manipulate the sensory qualities of foods to disguise their lower protein content. This leads to savoury-flavoured food that makes us think we’re eating protein when in reality it is loaded with carbohydrates and fats.

What Your Workout Says About Your Social Class

Tuesday, August 5th, 2014

Daniel Duane learned that weightlifting would protect him against sarcopenia — and learned first-hand what your workout says about your social class:

I learned to squat, deadlift, and bench press. I came to love the emotional catharsis of channeling aggression into the bar. I made new friends: A former Force Recon marine chatted with me between lifts, describing the first Gulf War and how he’d nearly died falling from a helicopter; a massively muscled, bald kickboxer, who happened also to be a handsome gay biotech lawyer, stood behind me during bench press sessions, fingers under the bar, making sure I didn’t hurt myself.

I adored lifting with these men. It was the happiest I had ever been in a gym. A faster runner abandons you; a stronger lifter hangs out, kindly critiques your form, and waits his turn. My strength numbers shot upward, and so did my body weight: 190 pounds, 200, 210, 215. I bought baggy pants and shirts. Walking down the sidewalk, I felt confident. At parties with my wife, I saw men who ran marathons, and they looked gaunt and weak. I could have squashed them.


Friends came for dinner. A public-interest lawyer, noticing I was bigger, asked what I’d been up to.

“I’m really into lifting weights right now,” I said. “Trying to get strong.”

The lawyer’s wife, a marathoner and family therapist, appeared startled, as if concerned about my emotional state. She looked me in the eye and said, “Why?”

Sociologists, it turns out, have studied these covert athletic biases. Carl Stempel, for example, writing in the International Review for the Sociology of Sport, argues that upper middle class Americans avoid “excessive displays of strength,” viewing the bodybuilder look as vulgar overcompensation for wounded manhood. The so-called dominant classes, Stempel writes — especially those like my friends and myself, richer in fancy degrees than in actual dollars — tend to express dominance through strenuous aerobic sports that display moral character, self-control, and self-development, rather than physical dominance. By chasing pure strength, in other words, packing on all that muscle, I had violated the unspoken prejudices — and dearly held self-definitions — of my social group.

Differences between Organic and Non-Organic Food

Tuesday, July 22nd, 2014

A new study finds significant differences between organic and non-organic food:

The study, funded jointly by the European Framework 6 programme and the Sheepdrove Trust, found that concentrations of antioxidants such as polyphenolics were between 18-69% higher in organically-grown crops. Numerous studies have linked antioxidants to a reduced risk of chronic diseases, including cardiovascular and neurodegenerative diseases and certain cancers.

Substantially lower concentrations of a range of the toxic heavy metal cadmium were also detected in organic crops (on average 48% lower).

Nitrogen concentrations were found to be significantly lower in organic crops. Concentrations of total nitrogen were 10%, nitrate 30% and nitrite 87% lower in organic compared to conventional crops. The study also found that pesticide residues were four times more likely to be found in conventional crops than organic ones.

Cool It in the Bedroom

Monday, July 21st, 2014

Cool it in the bedroom, a new study recommends:

For the new study, published in June in Diabetes, researchers affiliated with the National Institutes of Health persuaded five healthy young male volunteers to sleep in climate-controlled chambers at the N.I.H. for four months. The men went about their normal lives during the days, then returned at 8 every evening. All meals, including lunch, were provided, to keep their caloric intakes constant. They slept in hospital scrubs under light sheets.

For the first month, the researchers kept the bedrooms at 75 degrees, considered a neutral temperature that would not prompt moderating responses from the body. The next month, the bedrooms were cooled to 66 degrees, a temperature that the researchers expected might stimulate brown-fat activity (but not shivering, which usually begins at more frigid temperatures). The following month, the bedrooms were reset to 75 degrees, to undo any effects from the chillier room, and for the last month, the sleeping temperature was a balmy 81 degrees. Throughout, the subjects’ blood-sugar and insulin levels and daily caloric expenditures were tracked; after each month, the amount of brown fat was measured.

The cold temperatures, it turned out, changed the men’s bodies noticeably. Most striking, after four weeks of sleeping at 66 degrees, the men had almost doubled their volumes of brown fat. Their insulin sensitivity, which is affected by shifts in blood sugar, improved. The changes were slight but meaningful, says Francesco S. Celi, the study’s senior author and now a professor at Virginia Commonwealth University. “These were all healthy young men to start with,” he says, “but just by sleeping in a colder room, they gained metabolic advantages” that could, over time, he says, lessen their risk for diabetes and other metabolic problems. The men also burned a few more calories throughout the day when their bedroom was chillier (although not enough to result in weight loss after four weeks). The metabolic enhancements were undone after four weeks of sleeping at 81 degrees; in fact, the men then had less brown fat than after the first scan.

The message of these findings, Celi says, is that you can almost effortlessly tweak your metabolic health by turning down the bedroom thermostat a few degrees.