Some scientists offer mice and rats a spread of junk food and find that only some overeat and become obese, while others maintain a normal body size.
Obesity rates have increased dramatically in the US and around the world due to the availability of cheap, high calorie foods. Not everyone who overeats and becomes overweight will develop obesity-related diseases, however, and researchers are still trying to determine why there is such variation in individual responses to weight gain.
If you're looking for answers, the best place to check is an 11-by-11.5-foot room in a suburb of Washington, D.C. I spent a day there this summer, and I was one of fewer than 100 patients who did so this year.
The National Institutes of Health Clinical Center's airtight “metabolic chamber” is only furnished with an exercise bike, a toilet, and a bed. For 23 hours in June, I was sealed in the chamber while nurses monitored me constantly through a plexiglass window and video camera in the ceiling.
Since I was being measured for every calorie I used, I had to send back any leftovers through the wall so it could be recorded. I had a heart monitor and three accelerometers on my wrist, waist, and ankle that tracked my heartbeat and every movement.
There are approximately 30 metabolic chambers in the world and the NIH (National Institutes of Health) has three of them. These chambers are very sensitive and cost millions of dollars. They are considered the best way to measure metabolism. Studies done with these chambers have helped researchers understand obesity, metabolic syndrome, and diabetes better. These diseases are now some of the most threatening diseases to global health. The chambers allow researchers to see how individuals bodies respond to different amounts of calories.
My normal weight would be used as a control in an obesity phenotyping study with the goal of finding a cure for obesity.
I wanted to join the study not only for the sake of science, but also for my own personal reasons. As kids, my brothers and many of my friends seemed to be able to stuff their faces with junk food and not gain any weight, while today my husband can eat mountains of pasta and stay skinny. On the other hand, I've always noticed that the scale goes up quickly when I'm not careful about what I eat. I've always suspected that having a “slow metabolism” might help explain my lifelong struggle to keep my weight under control.
It was exciting and rare to have the opportunity to be a self-imposed NIH prisoner and get to see one of the most important scientific tools in obesity research up close. I finally got some answers on this long-simmering question about my body.
But what I learned from my day observing in the chamber was that I had really misunderstood how my metabolism worked. And that being obsessed with how fast your metabolism is can be destructive and distracting, and is based on a myth about obesity and weight management.
Metabolism, explained
If you have taken a look at the covers of women's magazines, watched Dr. Oz's TV show, or walked down the supplement aisle at the grocery store, you might think that your metabolism is one single thing that can be improved with “metabolism boosters” like chili peppers or coffee, or by following specific diets.
Metabolism is the process of the body breaking down food and converting it into energy. The rate of metabolism is different for everyone and can be affected by certain environmental and lifestyle factors.
The body uses calories in three main ways. The first is to maintain basic body functions like the heart, brain, and cells. This is called the basal metabolism. The second way is to process food. This is called the thermic effect of food. The third way is to burn calories during physical activity. Examples of this are walking, fidgeting, and exercising.
The largest amount of calories a person burns each day is from the basal metabolic rate, which is 65 to 80 percent for most adults. Physical activity is a much smaller portion, at 10 to 30 percent for most people, despite what many people believe. Digesting food is about 10 percent.
There are several things that predict how fast or slow a person’s metabolism will be, including the amount of lean muscle and fat tissue in the body, age, and genetics. Women usually burn fewer calories than men do. Having a higher metabolic rate means that your body uses food for fuel more quickly, instead of storing it as fat. However, you can still gain weight if you eat more calories than your body needs. Even though it may seem strange, people who weigh more often have higher metabolic rates than thin people do, because they need more fuel to meet the demands of their larger bodies.
The processes which are essential to any living organism are complex and scientists had been working hard to unravel them for centuries before the obesity crisis hit.
The debunking machine
The most precise tool available to track gas exchange minute by minute is the metabolic chamber, also known as a whole-room calorimeter.
The National Institutes of Health's three research chambers, opened in 2007, are devoted to studying the obesity epidemic. Eighteen researchers use the chambers to conduct approximately 400 studies each year as part of a larger unit focused on understanding weight problems, obesity, and diabetes, which affect up to one-third of the world's population.
Researchers have studied thousands of subjects in the metabolic unit in order to show how the metabolism is adaptable and how it works with our appetite, body composition, and physical activity levels to adjust the calories we’re burning.
In other words, if we take a medication that causes us to burn more calories, we will end up eating more to make up for the calories we've burned.
They discovered that if people are exposed to cold temperatures while they sleep, they will build up more brown fat. Brown fat is a type of fat tissue that produces heat. Also, they will burn more calories. (When the study participants slept in warmer temperatures again, the results were the complete opposite. This just goes to show how complex metabolism is.)
The study found that people who crash dieted and lost a lot of weight had a slower metabolic rate than those who lost weight at a slower pace.
Many studies suggest that our metabolism changes in ways that we are not usually aware of under new conditions and environments.
Researchers have found that a high-fat and low-carb ketogenic diet is not better at burning body fat than a higher-carb diet, despite what many people believe.
Weight Loss Myths You Probably Believe
Weight Loss Always Means Fat Loss
If you notice a sudden decrease in weight, especially overnight, you may be excited that you are losing weight so quickly. However, this may not be fat loss but water weight. Abbey Sharp, RD, owner of Abbey's Kitchen, explains that “Water weight is extra water that is hanging around the tissues, joints, and body cavities between cells.” This is different from body fat and not linked to calories consumed or expended. A sudden increase in water weight could be because of eating too much sodium or a change in hormones, but it can quickly be lost through exercise or drinking enough water.
You Can Target Trouble Spots
You may be concerned about the weight on your thighs and want to slim them down, but you cannot target fat loss from specific regions of your body through diet. Exercise can tone muscle, which may make specific body parts look slimmer.
Lose Weight Fast with a Juice Cleanse
Although juice cleanses may reduce calorie intake, they also involve consuming large amounts of sugary liquids, which can lead to blood sugar spikes and weight gain. Additionally, depriving oneself is not an effective strategy.
When you significantly reduce the amount of calories you consume, your body goes into a state of conservation. This is because it doesn't know when it will get its next meal. Nutritionist Ilyse Schapiro points out that while juice cleanses may lead to weight loss, going too low on calories for too long can have the opposite effect.
Drastically Cut Calories to Lose Weight Quickly
Not only can this lead to numerous physiological consequences, it's also often unsustainable in the long-term.” Both experts agree that going on a super low calorie diet is more likely to set you up for failure than help you lose weight. Brown explains that under-fueling is just as risky as over-fueling, while Moskovitz adds that this type of diet is often unsustainable in the long term.
Ditching Carbs Will Help You Slim Down Fast
will undoubtedly lead to fainting, as well as a host of other issues. People who want to lose weight quickly sometimes try a crash diet that eliminates all carbohydrates. Some people think that carbs cause weight gain, but this is not true, according to dietitian Jim White. Eliminating carbs can cause faintness and other problems.
You may actually gain weight by not including fiber in your diet, as it has been shown to help with weight loss.
You Can Exercise the Pounds Away
Although exercise can help with weight loss, it is mostly due to diet. Exercise only accounts for a small amount of energy expenditure and it is difficult to create a significant calorie deficit only through exercise. Even though working out has many health benefits that have nothing to do with weight loss, keep going to the gym. Just don't overdo it.
You Can Sweat Out Fat
Some people try to lose weight quickly by going to steam rooms or saunas to sweat it out. However, this only causes them to lose water weight. The body can easily add back water weight after eating salty food or drinking alcohol. Additionally, staying in a hot environment for a long time can be dangerous. It is important to talk to a doctor before using a steam room or sauna.
You'll See Results Immediately
Everyone is different when it comes to weight loss. Just because you are doing everything right, does not mean that the weight will fall off immediately. It could take some time to see results. Be patient and consistent and the results will show.
You'll Gain it All Back
While it is true that losing weight quickly can often mean gaining it back just as quickly, this is not always the case. Some people are able to lose weight quickly and keep it off with even small changes, so long as they are consistent. Do not worry if you have a couple of weeks where you lose a lot of weight – there are many ways to make sure you do not regain it.
It's Better to Lose Weight Slowly
The widely held belief that it is better to lose weight gradually rather than quickly is not borne out by evidence, according to a study conducted in 2014. Australian researchers looked at two groups of dieters, one of whom followed a 12-week program of rapid weight loss, while the other group followed a 36-week plan of gradual weight loss. Once the dieters had lost the weight, they were put on the same maintenance plan, and both groups regained weight at approximately the same rate. The study found that there is no significant advantage to losing weight slowly rather than quickly.
The metabolism myth
I put the phone down and thought about what had just happened in the room – and my desire to understand my body better.
Although I was successful in losing weight, NIH made me realize that there is still an epidemic of weight problems that has psychologically damaged many people.
I was surprised and relieved when the nurses and doctors said that my biomarkers were excellent and that I was very fit. I know that my weight is healthy, but I still feel like a chubby kid.
You don't need to have a history of weight problems to feel inadequate. Celebrities, big businesses, and wellness companies make billions of dollars by making us anxious about our physical appearance. They suggest that we can be skinnier, healthier, and have a better complexion if we only try a new exercise, buy a new gadget, or eat a certain way.
The main point of the text is that people respond to diets and exercises in different ways, and that one-size-fits-all weight loss advice often doesn't work.
The chamber has also shown that while some people have a “slow metabolism” relative to others their size and age, this isn’t a major cause of obesity. And despite the focus on “metabolism boosting” for weight loss, there’s nothing money can buy that will speed your metabolism up in a way that will lead to substantial slimming.
There was never one specific thing that helped me lose weight. I discovered different habits and routines that I could stick to that helped me eat less and move more.
I don't have a lot of unhealthy food in my house, I don't eat out often, I get a lot of sleep, and I try to eat a lot of fruits and vegetables. For exercise, I do it every day – walking or biking to work, or during lunch breaks. I find that I have more time for dedicated workouts in the mornings and on weekends.
I know that my ability to maintain my routines is strongly tied to my socioeconomic status and where I live. If I had more personal or financial stress, or lived in a different neighborhood with a long commute to work, I’d probably sleep less and eat more. I certainly wouldn’t be doing Pilates.
Although research from the chamber cannot fix socioeconomic problems that lead to obesity, a better understanding of human physiology and metabolism could help to create treatments that make it easier to lose weight. Lex Kravitz, an NIH neuroscientist and obesity researcher, said that even if a slow metabolism is not the cause of obesity, it may still be something that could be targeted to help with weight loss. The same is true for other illnesses such as diabetes and cardiovascular disease, which are often linked to being overweight.
The science from the chamber should dispel any myths about metabolism. It certainly dispelled any myths I had.
