Vox journalist spent a day in the metabolic room, one of 30 existing in the world.
The metabolic room is an expensive scientific tool that allows you to most accurately measure how many calories you are consuming and consuming. There are only 30 such rooms in the world. We translated for Zoznik’s readers a report on how it works.
When scientists feed junk food to test mice, they observe that only a few individuals overeat and grow stout while others remain of normal size. About the same thing happens to people.
The world was filled with available calories, and because of this, the average level of obesity increased significantly (from 1% in 1950 to 28% in 2018 – approx. Zozhnika). However, not everyone who eats enough is getting stout, and not everyone who is getting stout becomes sick of diseases like diabetes or heart disease (although with completeness the average risks increase greatly). Individual differences in metabolism can be quite significant.
The best way to find answers for yourself is to visit a special room measuring 3.3 x 3.5 meters in the vicinity of Washington. This summer I spent a day in such a metabolic room, one of the 100 patients who are examined there for a year.
How does the metabolic room
The National Institutes of Health (NIH) metabolic room is very minimalistic: there is only an exercise bike, a toilet and a bed. I spent 23 hours in it, while the medical staff watched me through the plexiglass wall and video camera in the ceiling.
Like a prisoner in a solitary cell, food was passed to me through a window, more precisely, through a special sealed gateway. And since scientists are counting every calorie, all food residues to the gram should be weighed and counted.
A pulse monitor and 3 accelerometers were fixed on me: on the wrist, waist, ankle – to measure every heart beat and movement.
In the world there are only about 30 metabolic rooms and there are as many as 3 of them in the NIH. This multimillion scientific instrument is the gold standard for accurate measurement of metabolism. With the help of the metabolic room, scientists measure how the subjects’ bodies react to calorie intake.
My visit to the metabolic room was timed to the study of obesity phenotypes, I acted as a representative of the “control” group. But I rather were interested in the conclusions about me personally.
My brothers since childhood consumed a lot of fast food and did not grow fat, my husband eats, it seems, tons of pasta and remains slim, but I always struggle with calories. And my doubts crept in: I thought that I had a “slow” metabolism and wanted to get a scientific justification for why it was so difficult for me to keep the weight I needed.
Being “imprisoned” in the metabolic room is a happy occasion to get accurate answers to your questions. And the day at NIH showed the depth of my misunderstanding of how my metabolism works.
Many people continue to think that metabolism is something that can be “accelerated” with the help of “boosters of metabolism”, drugs, special foods, or a diet. In reality, metabolism is thousands of chemical reactions to transform the energy that we consume in the form of food into fuel for the cells of our body. These reactions vary depending on the conditions of the environment or behavior, and depend little on our desire and control.
The body spends calories on three areas: 1. Basal (baseline) metabolism – the work of the heart, lungs, liver, brain and all other organs and cells. 2. The thermal effect of food – the cost of digesting and splitting incoming food. 3. The cost of physical activity – walking, exercise, in general, for any activity.
So for all physical activity for most people only 10-30% is accounted – depending on the level of human activity, the basic metabolism takes the lion’s share of the costs.
You can predict what will be the level of human metabolism based on body size, muscle and fat, age, sex (women tend to spend a little less kcal), and genetics (such predictions, for example, gives a calorie rate calculator). A higher level of metabolism means that the body will burn more kcal, but in any case, if you consume more calories than your body requires, weight will increase.
The history of the metabolic room
At the beginning of the 17th century, the Italian doctor Santorio Sanctorius (one of the first to begin researching metabolism) conducted one of the first experiments on human metabolism.
He invented “static chair-scales” to weigh himself before and after food, sleep, toilet, and even sex. He recorded fluctuations in body weight and suggested that this could be “imperceptible sweating”.
A hundred years later, the French chemist Antoine Lavoisier used an “ice calorimeter” for the same purpose. He measured the speed at which ice melts around cells with animals and concluded that the heat generated by animals or people is related to the amount of energy consumed.
Modern metabolic room, in fact, the development of ideas and experiences of Sanatorius and Lavoisier. Over the years of research, scientists have figured out the amount of oxygen consumed and the released carbon dioxide depends on the speed with which we use energy reserves (we spend calories). Measuring changes in the concentration of these gases in a sealed space allows you to accurately measure the characteristics of personal metabolism.
Metabolic room and myths
Metabolic room can be called “room-calorimeter” – this is the most accurate instrument for per-minute measurement of the composition of gases in the air of a room.
Three rooms at the National Institutes of Health (NIH) were launched in 2007 to focus research on countering the obesity epidemic, which involves about a third of the world’s population. About 18 scientists constantly use these rooms to conduct a total of about 400 studies per year.
Studies in metabolic rooms have helped scientists understand how adaptive the metabolism is, how it works and how it is associated with appetite, body composition, and physical activity.
For example, giving people a special medicine that eliminated (through urine) 360 kcal per day from the body, they found out (study) that this loss of calories is compensated by the body due to increased appetite and people just eat more.
Another research result: a decrease in air temperature during sleep causes the body to accumulate more brown fat (adipose tissue responsible for heat production) and burn more calories (study). It is curious that when they on the contrary subjected people to sleep at high temperatures, the results were reversed – the bodies burned fewer calories.
In another notable study, researchers examined 14 show participants Biggest Loser (weight loss show) – immediately after a 30-week trial of weight loss and after 6 years. Scientists have found that the participants’ metabolism slowed down and, in general, their bodies sought to consume the calories they had eaten before for a long time.
A single conclusion that can be drawn from the above examples: our metabolism quietly adapts to environmental conditions in a variety of ways.. Roughly speaking, while reducing calorie intake, it reduces calorie expenditure (metabolism slows down) and simultaneously looks for ways to increase calorie intake (increased appetite) and
As for diets, scientists have denied that the body burns more fat on the keto diet (a lot of fat and not enough carbohydrates) compared to a diet with a lot of carbohydrates, despite the whole hype around keto.
“We could assume that if we cut back on carbohydrate intake, we would lose more fat due to the fact that more energy would be taken from its oxidation. But the body very quickly adapts to the type of fuel that goes into it, ”says Kevin Hall, an obesity scientist.
Another general conclusion from research: that there is no magic, most effective for all diets for fat burning.
Metabolic puzzles that are not explained
But many metabolic myths are not explained.. For example, it’s not completely clear why 2 people with the same size and composition of the body have different levels of metabolism (burn a different amount of calories under the same conditions). Also not fully explained the different metabolic reactions to the same conditions: for example, some people with obesity develop insulin resistance and diabetes, and some do not. They also have not yet figured out why the level of diabetes is higher in some ethnic groups (black and Asian).
Scientists have also not yet figured out the mechanisms of how the brain understands that body weight has changed and makes adjustments to the level of metabolism. “If we knew thoroughly how the brain determines body weight and regulates calorie burning, we could change these settings to help an obese patient burn more calories,” says scientist Aaron Saypes.
He is exploring the possibility of creating a drug that does the same thing that makes cold air – helps to burn more calories.
How to measure my personal metabolism
My personal contribution to these studies is to take part in a number of physical tests (from pressure measurement to ECG) and spend a day in the metabolic room. In addition to directly observing how much I am moving and how much and what exactly I eat, scientists with high accuracy and every minute they will measure how many calories I have burned and at the expense of what exactly (in what proportion proteins, fats and carbohydrates were burned).
In response, I will receive unique and highly accurate data on how my body works.
Measurements before the day in the metabolic room.
I am 34 years old, height is 175 cm, weight is about 68 kg, my BMI is normal (body mass index, here’s how to calculate it BMI). But as a child I was a fat child, I loved sweet and fatty more than anyone in my family. As a teenager and after 20 years, I fought with excess weight. Then I moved to Italy and indulged myself with pizza, carpaccio, ice cream. I was smashed and I returned home in Canada a year later, depressed by the state of my body. I was covered with depression and it took me several years to begin the process of losing weight.
I have long believed that over weight years have wreaked havoc on my body: for example, I was sure that “my metabolism slowed down” and this was the reason that I gained and could not lose weight. Good thing I was wrong.
In the metabolic room, I ate, rested, and pedaled the bike for 30 minutes – all on a strict schedule. I also wrote down all my activities — when and how long I stood, lay, sat, read, pedaled — so that the scientists could complete their observations.
Before dinner in the metabolic room, Kong Chen, a scientist at the National Institutes of Health (NIH), visited the metabolic room and greeted me through a plexiglass window and asked how I felt.
I was surprisingly comfortable in a small closed room. I asked him to tell you exactly how the room measures the burning of calories.
Chen – a doctor in bioengineering – said that the metabolic room is practically airtight, with a fixed level of oxygen and carbon dioxide. With the help of a precision instrument built into the ceiling, through which all the air in the room passes, the amount of oxygen consumed by my body and carbon dioxide emitted every minute is measured.
We consume energy in the form of calories (in the form of proteins, carbohydrates or fats), but to “consume” these calories the body needs to oxidize them (“oxidation” is burning, the process with energy release), that is, the body needs oxygen for this. Oxygen, which is contained in the inhaled air, is involved in the oxidation of various chemical compounds, including their conversion into the energy needed by the body. A byproduct of this process is carbon dioxide (CO2).
The food in the metabolic room during the experiment is passed through special gateways.
When air from a room is sucked out and passes through the device, gas analyzers measure everything that a person in a room exhales and supply this information to a computer, where scientists calculate exactly how many calories are burned and in what proportion different types of fuel were oxylated.
The amount of carbon dioxide released by the body and the change in the proportions of carbon dioxide and oxygen also show where these calories came from – from proteins, carbohydrates, or fats.
Room devices are quite sensitive to the slightest changes and allow you to notice a change in the cost of calories by 1.5-2% for 24 hours, no other device yet allows it. “We can, for example, measure the slightest action on the metabolism of a drug,” Dr. Chen is proud.
Dr. Chen conducts a physical examination before the day in the metabolic room.
Another very accurate method: “double water mark method(You can read more in the post from Dmitry Pikul) – associated with the consumption of a special “labeled” heavy isotope of hydrogen (2H) and heavy oxygen (18O). Since these isotopes are very rarely found in the body, scientists can calculate how quickly these isotopes leave the body with urine (by making an appropriate analysis of urine). And although the accuracy of this method is quite high, it can still track changes in the metabolic rate over a period of 7-10 days with an accuracy of 5%, which is 2-3 times less accurate than the metabolic room.
But even small changes in metabolism are important, even a difference of 100 kcal per day over a long period of several years can turn into a few extra pounds in the form of fat (read about the rule “3500 kcal = 0.5 kg of weight”).
Dr. Chen himself was one of the first testers of the metabolic room: “I discovered that I have a more or less averaged level of metabolism. And I, like most people, should take care of what and how much I eat. I am not one of those who can eat as much as they want and not gain weight. ”
“You are fine”
The next morning I woke up a little tired and exhausted, after 6 hours of shallow sleep. I was let out through a heavy steel door and I found myself in the open air.
I was reminded to collect urine every day for analysis of labeled water to include this data in my metabolism study, I also continued to carry 3 accelerometers to accurately measure my activity. This data will help scientists understand my usual average calorie consumption in a typical mode of life outside a research center.
A few weeks later I received the data. Dr. Hall said “judging by the results, you are perfectly normal.” My metabolic rate coincided with typical predictions for a person of my age, gender, height and weight. In other words, I did not have a “slow metabolism”.
I burned 2330 kcal per day in the metabolic room, most of these calories (more than 1400 kcal / day) were my basic metabolism (the costs that the body incurs to maintain basic life activity – the work of the heart, lungs, liver and
Per minute costs of calories by the hour. (We believe that in this graph we are talking about the cost of calories on top of the base metabolism, which consumes about 2/3 calories – approx. Zozhnik).
For comparison: in 90 minutes of training on a stationary bike, I spent only 405 kcal (17% of all calories per day and less than the advertisement promises for cycling).
My other biomarkers — heart rate, cholesterol, blood pressure — were fine and did not bode well for risks that I thought I could have gained over the years of obesity.
By the way, the level of expenditure of calories during sleep is only 5% lower than when you relax in consciousness.
Another interesting observation: it was believed that during the solution of a complex mental task, the brain spends more calories than, for example, with watching a TV show. But Dr. Hall said that all their observations disprove this myth – the brain’s energy expenditure is approximately at the same level and our brain is always active, even in a dream.
As for calorie intake, I consumed 1,850 kcal per day in the metabolic room (18% in the form of protein, 36% in fats and 46% in carbohydrates) out of 2,250 kcal that I was offered. This means that on that day I experienced a calorie deficit, and if I continued to eat with such a difference, I would lose weight.
I also found it bad to forecast personal calorie intake. Completing the questionnaire and food diaries before the study, according to my calculations, it turned out that I consumed only 1500-2000 kcal per day and I was sure that I thought rather meticulously. But the day in the metabolic room showed that if I really consumed so many calories, I would be noticeably thinner than now.
Some blame “slow metabolism” for their excess weight, excessive consumption of sugar in particular, or carbohydrates in general, hormones and
“There is a type of people whose adaptive mechanism uses excess calories mostly to increase overall activity, and not to store in the form of fat reserves,” said Dr. Hall.
The truth is that each person is an individual and each body reacts differently to different diets, exercises, and there is no single recipe ideally suited to everyone.
The metabolic room shows that despite the fact that different people of the same size, body structure, sex and age can have a different metabolism (that is, someone a little faster, someone a little slower) – this does not mean that Some kind of “metabolism” in general can be called “slow” and as if it can be somehow “overclocked”.