When it comes to losing weight, people often want know the best way to shed excess pounds – and there’s no shortage of fad diets or fitness crazes claiming to have the “secret” to fat loss. One theory even suggests that exercising at around 60% of your maximum heart rate will bring our bodies into a so-called “fat burning zone”, optimal for losing weight.

But does this “fat burning zone” even exist?

First, it’s important to understand a little about our metabolism. Even if we were to sit at our desk all day, our body still needs “fuel” to meet energy demands. This energy comes from carbohydrates, proteins, fats and phosphates. However, the rate at which we use them, and how much we have available, varies between people. It depends on a number of factors, such as dietary intake, age, sex and how hard or often we exercise.

Generally, exercising at lower intensities – such as sustained walking or light jogging – doesn’t require as much effort by our muscles as sprinting, for example. This means the amount of energy needed by the body is lower, so energy supply predominantly comes from fats.

But as exercise intensity increases, fat can’t be metabolized fast enough to meet increased energy demand. So the body will use carbohydrates, as these can be metabolized more rapidly. This means there is indeed an exercise intensity where fat is the predominant energy source.

At the lower end of this spectrum is our resting state. Here, the number of calories our body needs to function is considerably low, so the body primarily metabolises fat to use for energy. This means the potential “zone” for metabolising fat is between the rested state and the level of exercise intensity where carbohydrates become the dominant energy source (in terms of percent contribution to energy demand).

But this is a wide range, which lies between a resting heart rate of around 70 beats per minute to around 160 beats per minute during moderate effort exercise (such as cycling at a constant speed where holding a conversation becomes challenging), where the crossover from using fat to carbohydrates for energy occurs.

The issue with such a wide zone is that the person exercising wouldn’t necessarily be optimising their ability to metabolise fat, because as the exercise intensity increases there’s a gradual change in the balance of fat and carbohydrates your body uses for energy.

Fat Burning Zone

So how can we know at which point our body will switch from using fat to other fuels for energy? One approach researchers take is assessing how much fat is being used for energy during different exercise intensities.

By measuring how much air a person expels during an exercise test which gets progressively harder, physiologists have been able to calculate the relative contributions of fat and carbohydrates to meet the exercise demand at different intensities. The highest amount of fat burned is called the “maximal fat oxidation rate” (or MFO), and the intensity this occurs at is termed “FATmax”.

Since this method was first used by researchers, studies have shown that as the intensity rises from around 40-70% of a person’s VO₂ max – which is the maximum amount of oxygen a person can use during exercise – there’s an increase in the rate of carbohydrates and fats being used. The rate of fat being burned starts to decline at higher intensities as the body requires energy more rapidly.

The so-called “fat burning zone” has been shown to occur anywhere between about 50-72% of a person’s VO₂ max. However, the ability to burn fat is also based on genetics, with studies showing that this fat burning zone is likely to be lower in overweight or obese people – around 24-46% of their VO₂ max – and higher in endurance athletes.

Another point to consider is how much fat we actually burn during exercise (if we express it in grams per minute). The answer is: surprisingly little. Even in studies with athletes, at FATmax, participants only burned on average a mere 0.5 grams of fat per minute. This would equate to around 30 grams of fat per hour.

In the average person, this appears to be even lower, ranging between 0.1 and 0.4 grams of fat per minute. To put it in perspective, one pound of fat weighs around 454 grams. So, though training in this fat burning zone will help with fat loss, this might also help explain why it takes some people longer to lose fat through exercise.

But there is evidence that following certain diets (such as intermittent fasting or a ketogenic, high fat diet) and longer exercise can increase the actual amount of fat we burn.

Perhaps it’s time to no longer consider “burning fat” to have a “zone”, but rather an individualized “sweet spot” which can be used to optimise our exercise regimes to lose weight. Regular physical activity around this “sweet spot” (which typically occurs at a low to moderate feeling of effort, for example 30-60% of your maximal effort, or a perceived exertion level of one to four out of ten) will likely improve our body’s efficiency in using fat for energy – and translate to a lower overall body fat percentage.

Justin Roberts is a Principal Lecturer at Anglia Ruskin University.

Ash Willmott is a Lecturer in Sport and Exercise Science at Anglia Ruskin University.

Dan Gordon is a Principal Lecturer Sport and Exercise Sciences at Anglia Ruskin University.

Source: https://getpocket.com/explore/item/fat-burning-zone-the-best-way-to-exercise-to-burn-fat?utm_source=pocket-newtab-intl-en

In the summer of 2009, I was finishing the first—and toughest—year of my doctorate. To help me get through it, while I brewed chemicals in test tubes during the day, I was also planning a crazy experiment to cheat sleep.

As any good scientist would, I referred to past studies, recorded data, and discussed notes with some of my colleagues. Although the sample size was just one—and, obviously, biased—I was going to end up learning a great deal about an activity that we spend nearly a third of our life doing.

With looming deadlines and an upcoming thesis defense, I was determined to find more hours to fit in work and study. The answer came from reading about the famous American inventor Buckminster Fuller, who, Time reported in 1943, spent two years sleeping only two hours a day.

Fuller’s Short Dreams

The method to achieving what seemed like a superhuman feat was called the Dymaxion sleeping schedule: four naps of 30 minutes taken every six hours. Much of Fuller’s inventions were labeled “Dymaxion,” which is a portmanteau of dynamic, maximum, and tension, and I was certainly inspired to live like a great man once did.

When I started reading the scientific literature on the topic, I was surprised by how little we know about sleep. And the little we can explain comes from studying the effects of the absence of sleep. The average duration of a night’s sleep has been declining in recent years. In the US more than a third of the population gets less than seven hours of sleep in the day, and in the UK a similar proportion gets away with less than six hours.

Not sleeping properly causes problems, so we say that sleep is essential to many functions such as memory and cognition. But why we sleep and what ill-effect sleep deprivation may have remain poorly understood.

That lack of knowledge, however, hasn’t stopped people from experimenting with sleep. My experiment began in 2009, and today there are many more online forums dedicated to discussions around what is now referred to as “polyphasic sleep.” People have scoured past examples, such as the life of Leonardo da Vinci, to develop new polyphasic schedules. Like the Dymaxion schedule, the general idea is to break the large chunk of sleep at night in to multiple naps and thus reduce the total time spent sleeping.

The Experiment Begins

I saw that there were risks to what I was about to try, but I was also really fed up with dealing with my frequent grogginess just because I didn’t sleep eight hours each night. I jumped into the experiment and told a few good friends to keep a close eye on me; if anything seemed awry I would stop.

At the time, I didn’t drink tea or coffee and I wasn’t sad about giving up alcohol. Both caffeine and alcohol affect sleep, and I wasn’t taking chances with something that was going to require so much effort.

For the sleep schedule to work, I needed places to nap. I had a few secret spots in my huge chemistry lab at Oxford University (far away from any chemicals, of course). Better still, I had access to a couch in my college nearby.

My Australian housemate Alex at the time wanted to tame sleep too and decided to join in. We set about imitating Fuller and decided to take 30-minute naps every six hours.

Problems began after 36 hours. I was finding it hard staying awake at night, and Alex wasn’t able to wake up in time after naps despite many alarms.

We were aware that difficulties were bound to arise, but we didn’t realize how bad sleep deprivation truly feels. Alex went back to being monophasic, but I was determined. To make it work, I changed to an easier sleep schedule: the Everyman, where I slept for 3.5 hours at night and took three 20-minute naps in the day.

After three weeks and a few more obstacles, I finally settled into the new schedule. I was getting 4.5 hours of sleep in total, which was just a little more than half the hours I used to sleep.

The extra time was proving to be a wonderful benefit: I finished my first-year thesis; successfully defended it; decided that after finishing my doctorate I didn’t want to be in academia for the rest of my life; got a chance to explore Oxford University’s wonderful offerings without sacrificing on lab time; started exploring other career options, including writing, which eventually led me to become a journalist.

There were other gains. I found myself waking up fully refreshed after a nap. Quite often, before the alarm began ringing. The best bit was that I was benefitting from that superb early-morning blank mind four times a day instead of just once.

Others who’ve tried polyphasic sleeping had mentioned similar benefits. But what really surprised me was that I had managed to do something that seemed impossible going in.

Wasting No Sleep

Sleep expert Claudio Stampi explained in his 1992 book Why We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep that humans shouldn’t find it hard to adjust to a polyphasic schedule.

Many animals are known to be polyphasic sleepers, and our hunter-gatherer ancestors may have been too. But we don’t even need to go so far back in time to find examples of polyphasic humans.

As Roger Ekirch notes in At Day’s Close: A History of Nighttime, a segmented sleep pattern was common as recently as the 18th century.

Back then people often slept for four hours, then woke up for an hour or two before going back to bed for another four hours. In the period they were awake at night, people smoked, had sex, and even visited neighbors. It was the advent of night-time lighting that allowed us to squeeze in more awake time doing things and made people adapt to what is today’s monophasic sleep.

Sleep to Dream

A few decades ago, Stampi ran a polyphasic-sleep study to find out what happens to the brain under such circumstances. With the help of electric probes attached to a willing participant’s skull, Stampi compared how normal sleep cycles adjust to polyphasic sleep.

We may not realize it, but monophasic sleep is broadly divided into three stages. The first stage is that of light sleep consisting of rapid theta waves. The second stage is that of deep sleep characterized by slow delta waves. And finally, the last stage when we dream can be spotted with the help of rapid eye movements (REM).

During a night’s sleep, these three stages repeat in a cyclic manner over 90 to 200 minutes. But Stampi’s subject, who had adapted to taking six 30-minute naps per day, known as the Uberman schedule, seemed to have broken down those stages to fit them in during his short naps. In some naps he was in the first stage or the second stage, and in others he experienced REM.

Among the three phases, we understand REM’s role the best. It is believed to be key to learning and forming memories. People taught a skill and deprived of REM sleep, were not able to recall what they had learned. However, Stampi noted that the various stages of sleep were experienced in the same proportions in polyphasic sleeping, as the subject experienced them during monophasic sleeping, indicating that all stages were important.

I couldn’t find a scientific study on the sleep cycles in an Everyman schedule, but I noted that during at least one or two of my daily naps I experienced dreams, which are a sign of entering REM sleep. So it meant that I was probably directly entering the very last stage of monophasic sleep in a short nap.

And sometimes these dreams were lucid. In them, I was aware that I was dreaming and sometimes I was able to make conscious decisions in the dream. For instance, once after a long session of Assassins’ Creed, I found myself in a lucid dream where I was present in the virtual world of the video game. Though there were no people around to kill or interact with, I was able to choose which direction I wanted to go next to explore this world that I had come to know well from spending hours in front of a screen.

There are scientific explanations for why such dreams occur. But there remains skepticism because there is no way to test what are, by definition, self-reported observations.

Source: https://getpocket.com/explore/item/i-once-tried-to-cheat-sleep-and-for-a-year-i-succeeded?utm_source=pocket-newtab-intl-en

Brittany Bankhead-Kendall arrived in Boston in July of 2019. Tall and trim, with straight, blond hair, bright-blue eyes, and an easy smile, she has a sunny disposition and the hint of a Texas drawl. She had just finished a general-surgery residency in Texas, and, at Massachusetts General Hospital, she would complete her training as a trauma and critical-care surgeon. As summer eased into fall, she struggled to acclimate to the weather. At the hospital, she operated on patients who’d suffered serious injuries—people hurt in car accidents or house fires, or by gunshots. Patients would arrive with fractured skulls and ruptured spleens, collapsed lungs and bleeding bowels. Bankhead-Kendall got good with gore.

In March, 2020, as the coronavirus descended on Boston, she learned that her role would evolve. She would be stationed in the I.C.U., where the sickest COVID-19 patients would be treated, and start working primarily as a physician, not a surgeon. Bankhead-Kendall read with care the flurry of hospital-wide e-mails detailing new procedures and protocols: where patients would be isolated, how P.P.E. would be rationed, when additional staff would be called in. Keeping track of new information felt like a full-time job. Still, at first, the surge didn’t materialize. “There was just this impending sense of doom,” she told me recently, over Zoom. “Then, all of a sudden, it was at our doorstep.”

The first COVID-19 patient she cared for was a woman in her mid-thirties. (Some details have been changed to protect patient privacy.) The woman was admitted to a step-down unit—the rung between an I.C.U. and a general-medicine floor—and, though previously healthy, she now needed concentrated oxygen delivered through a nasal tube to insure safe levels in her blood. Bankhead-Kendall’s shifts began in the evenings. When she arrived, she’d stop by the patient’s room. She’d watch her breathing through a window, record her vital signs, review her blood tests, and consider whether and when she should intubate her. For a few days, the woman was the only COVID-19 patient in the hospital.

Then things accelerated. One patient became three, three became ten, ten became thirty—an overwhelming deluge of COVID-19 patients. Her nightly rounds transformed into an escalating struggle. “We just tried to stay afloat,” Bankhead-Kendall said. “It was pure survival mode.” She was tapped to join the hospital’s “airway team”—a group who rushed to intubate patients when their breathing collapsed. The airway team received emergency pages and overhead alerts; when the alerts came, with alarming frequency, Bankhead-Kendall sprinted with a neon backpack full of supplies to the patient’s room, where doctors, nurses, and respiratory therapists had converged. A swift, coördinated ritual commenced. The patient could be unconscious or heaving and coughing, spraying virus everywhere. A mask connected to an oxygen bag would be placed over his nose and mouth. Someone would lower the head of the bed, another would guide a catheter into a vein (or, if that failed, drill it into a bone), and a third would administer sedative medications. Yet another doctor—sometimes Bankhead-Kendall—would peer down the patient’s throat, spy the vocal cords, and insert a plastic tube, while others monitored, prepared to perform C.P.R.

Bankhead-Kendall had never experienced anything like this. The number of patients needing intubation kept rising; often, she was startled by the speed with which their breathing declined. Debates erupted over whether the team should start intubating patients sooner, to prevent the chaos of doing it in a rush later, or continue waiting, to give patients a chance to recover without ventilators. These questions were further complicated by a constant fear of infection. Doctors were still learning about how they might keep themselves safe; intubation was already seen as among the riskiest of medical procedures. Bankhead-Kendall, who has asthma and regularly uses an inhaler, felt especially vulnerable. “Whenever I got coughed on, it felt like a death sentence,” she said. “Every day I thought, This could be the end.” She rewrote her will and told her parents where to find her passwords and what to do if she ended up on a ventilator. She taped important documents to the inside of her apartment’s front door—if she died, and someone had to enter her home, she didn’t want them to risk getting infected.

When I started speaking with Bankhead-Kendall this spring, a year had elapsed since the start of the pandemic. She had begun to emerge, shaken, from the most physically and emotionally taxing experience of her life. As a physician myself, who had also treated large numbers of COVID-19 patients at a big-city hospital, I was trying to understand what the pandemic’s stresses had done to health-care workers and their families. Clinicians have suffered extraordinary levels of mental distress during the pandemic; many have reported anxiety, depression, suicidal thoughts, and symptoms of post-traumatic stress disorder. According to some estimates, more than three thousand health-care workers have died after being infected by the virus. Today, thanks to vaccines, the medical crisis of the pandemic is starting to wane. And yet its mental-health consequences will linger, for patients and doctors. For Bankhead-Kendall, as for many other clinicians, this has been a long year of fear, despair, isolation, and tenuous resilience.

In Boston, last year, February turned to March, and the winter deepened. Days of viral surge became weeks. Bankhead-Kendall started to feel the weight of the never-ending intubations. She was often charged with calling families to discuss the procedure, and she found that people viewed it with horror. “Being part of the intubation team meant being a person that patients and families saw as a ticket to death,” she told me. “I went into medicine to help people—now I was someone they feared.” Despite her exhaustion, she started to have trouble sleeping. When she did fall asleep, she was jolted awake by nightmares. She saw huge masses of sick people, coughing, bleeding, gasping for air. She watched as they approached the hospital and burst through the doors of the emergency department, crying for help. She saw herself standing alone—stunned, angry, confused—choosing who would live and who would die.

Bankhead-Kendall was born and raised in West Texas. The eldest of three daughters, she was determined and ambitious. Her father was a petroleum engineer and her mother a teacher, but she knew from an early age that she would be a doctor. One day, in middle school, she rushed home beaming, carrying a small object wrapped in Kleenex; inside was a sheep’s eye. She told her mother, “I was the only one in class who cut it out without tearing anything.” When she was in the seventh grade, her family relocated to Argentina; within weeks, she decided to run for class president. “I said, ‘Brittany, no one knows you here! Are you sure?’ ” her mother, Athena Bankhead, told me recently. “She didn’t win, but after her speech everyone knew who she was. She was never afraid to put herself out there.”

The family soon moved back to Texas. Bankhead-Kendall attended college at Texas A. & M., where, during her senior year, she met her future husband, Brian Kendall, in a medical-communications class. After graduation, she moved to Miami to start a master’s program in biomedical sciences; Brian entered the Peace Corps and worked in Albania as a health-education volunteer, then joined Brittany in Miami. They became active in a local church and, to make ends meet, picked up shifts at a nearby golf course (he worked as a bag boy, she drove a beverage cart); they used their tip money to buy health insurance. In 2008, they married. They applied to medical school together, while on their honeymoon, in Bali. They had a son, Knox, while in medical school, and a daughter, Tinsley, six years later, during their residencies.

In 2019, the family moved into a two-bedroom apartment in Cambridge, Massachusetts, near the Longfellow Bridge, just across the Charles River from Boston. Brittany started her fellowship in surgical critical care, and Brian worked as an E.R. physician at two community hospitals north of the city. In March, as coronavirus cases surged across the Northeast, they began spending nearly all their time at their hospitals. Brittany was working a string of fourteen-hour overnight shifts when Boston’s schools closed. Between shifts, unable to sleep, she lay in bed reading the Internet: one browser tab contained lesson plans for her son, another emerging evidence on how to treat COVID-19. She began to have a terrible feeling that, during the pandemic, it would be impossible for her to be a good parent and a good doctor simultaneously.