Most of us who are concerned about our health and weight are familiar with the term metabolism. Learning more about this complicated process can help you understand the steps to better weight management.
Metabolism can generally be broken down into two processes: catabolism and anabolism.
- Catabolism is the process that breaks down compounds or molecules (typically from food) to release energy. This energy is used to fuel body processes such as movement.
- Anabolism is the building of complex compounds or molecules from simpler compounds. This process usually requires energy. Anabolism allows your body to maintain cells and build new ones.
What you weigh is mostly the result of your catabolism minus your anabolism — the amount of energy (food) you put into your body minus the amount of energy your body uses.
Now that we understand metabolism a bit better, let’s go through some metabolism myths.
- YOUR METABOLISM IS IN EVERY CELL IN YOUR BODY.
A lot of people talk about their metabolism like it’s a muscle or organ they can somehow control. But in reality, the term refers to a series of chemical processes in each cell that turn the calories you eat into fuel to keep you alive.
The body’s major organs—the brain, liver, kidneys and heart—account for over half of the energy burned at rest, while fat, the digestive system and especially the body’s muscles account for the remainder.
2. MOST OF THE ENERGY YOU BURN IS FROM YOUR RESTING METABOLISM.
There are three main ways you burn energy: a) the basal metabolism, which is the energy used for your body’s basic functioning while at rest; b) the energy used to break down food, also known as the thermic effect of food; and c) the energy used in physical activity.
One very underappreciated fact about the body is that your resting metabolism accounts for a huge amount of the total calories you burn each day. Physical activity, on the other hand, accounts for a tiny part of your total energy expenditure—about 10 to 30 per cent (unless you’re a professional athlete or have a highly physically demanding job). Digesting food accounts for about 10 per cent.
3. METABOLISM CAN VARY A LOT BETWEEN PEOPLE, AND RESEARCHERS DON’T UNDERSTAND WHY.
It’s true that two people with the same size and body composition can have different metabolic rates. One can consume a huge meal and gain no weight, while the other has to count calories. Researchers have been able to find some predictors of how fast a person’s metabolism will be. These include: the amount of lean muscle and fat tissue in the body, age and genetics (though researchers don’t know why some families have higher or lower metabolic rates). Sex also matters, since women with any given body composition and age burn fewer calories than comparable men.
You can’t easily measure your resting metabolic rate in a precise way. There are some commercially available tests, but the best measurements come from research studies that use expensive equipment. However, you can get a rough estimate of your resting metabolic rate by plugging some basic variables, like age, height and weight, into online calculators. These will tell you how many calories you’re expected to burn each day, and if you eat that many and your weight stays the same, it’s probably correct.
4. ANOTHER THING THAT SLOWS DOWN THE METABOLISM: GETTING OLDER.
The effect happens gradually, even if you have the same amount of fat and muscle tissue. So if you’re 60, you’ll burn fewer calories at rest than you did when you were 20.
This continual decline starts in young adulthood—and why this happens is another metabolism question researchers haven’t answered. “Why do your energy needs go down as you age, even if you keep everything else pretty much the same? That’s one of the bigger mysteries.”
5. YOU CAN’T REALLY SPEED UP YOUR METABOLISM FOR WEIGHT LOSS.
There’s a lot of hype around “speeding up your metabolism” and losing weight by exercising more to build muscle, eating different foods or taking supplements. But it’s a myth.
While there are certain foods—like coffee, chili and other spices—that may increase the basal metabolic rate just a little, the change is so negligible and short-lived, it would never have an impact on your waistline.
Building more muscles, however, can be more helpful. Here’s why: one of the variables that affects your resting metabolic rate is the amount of lean body mass you have. At any given weight, the more muscle on your body, the higher your metabolic rate. That’s because muscle uses a lot more energy than fat while at rest.
So the logic is, if you can build up your muscle, you’ll have a higher resting metabolism and will burn the fuel in your body more quickly. But there’s a caveat.
6. DIETING CAN SLOW DOWN YOUR METABOLISM.
While it’s extremely hard to speed up the metabolic rate, researchers have found there are things that can slow it down—like drastic weight-loss. For years, researchers have been documenting a phenomenon called “metabolic adaptation.” As people lose weight, their basal metabolic rate actually slows down to a greater degree than would be expected from the weight loss.
To be clear, it makes sense that losing weight will slow down metabolism. Slimming down generally involves muscle loss, which, in turn, means the body doesn’t have to work as hard to keep running. But the slowdown after weight loss, researchers have found, often appears to be substantially greater than makes sense for a person’s new weight.
Once you gain weight and keep the weight on for a period of time, the body can get used to its new, larger size. When that weight drops, a bunch of subtle changes kick in—to the hormone levels, the brain—slowing the resting metabolism and having the effect of increasing hunger and decreasing satiety from food, all in a seeming conspiracy to get the body back up to that set point of weight.
7. RESEARCHERS DON’T FULLY UNDERSTAND WHY THIS METABOLIC SLOWDOWN HAPPENS.
There are some interesting hypotheses, however. One of the most persistent is an evolutionary explanation. Today, the thinking goes, this inability to lose weight is our body defending against periods of undernutrition, even though those are now much rarer.
But not all researchers agree with this so-called “thrifty gene” hypothesis. As epigeneticist John Speakman wrote in a 2013 Annual Review of Nutrition analysis, one issue with the hypothesis is that not everybody in modern society is overweight. The evolution of our genetic predisposition to store fat is complex. It involves a frequently changing environment, interactions of specific genes with that environment, and even interactions between genes. This interplay of factors is still a mystery.
Now here are some additional effective steps you can take to increase your metabolism.
- Get an appropriate amount of sleep. For most adults, about 7 to 8 hours is recommended. Children usually need more.
- Drink plenty of water throughout the day.
- Cut heavily processed foods from your regular diet.
- Limit alcoholic beverages. Your body will metabolize the alcohol first. The food will sit and wait.
Stay healthy and keep that body moving.
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