It is a very common complaint among dieters: “Ugh, my metabolism is so slow, I’m never going to lose weight.”
When people talk about a fast or slow metabolism, what they are really trying to say is how many calories their body burns throughout the day.
The idea is that someone with a slow metabolism just won’t use the same amount of energy to do the same task as someone with a fast metabolism.
But does the rate of metabolism vary that much from person to person?
I am a nutrition expert who focuses on the biological, environmental and socioeconomic factors that influence body composition and this question is more complicated than it seems at first glance.
But whatever the current speed of your metabolism, there are things that will push it to run at lower or higher speeds.
Energy needs of your body
The metaboli smo is a biological term that refers to all the chemical reactions necessary to maintain life in an organism.
Your metabolism does three main jobs: converting food into energy; break down food into its basic components (proteins, lipids, nucleic acids and some carbohydrates); and remove nitrogen waste.
If you are distressed by the speed of your metabolism, you are probably concentrating on the amount of energy you get from the food you eat and the amount your body uses.
The energy value of a food is measured in calories.
Your caloric needs can be divided into two categories.
The basal metabolic rate is the minimum amount of calories required for basic functions at rest.
The energy expenditure at rest is the amount of calories the body uses while resting or sleeping, which is equivalent to about 60% – 65% of your total spend of energy.
It does not take into account the calories you need for everything else you do, such as moving or energy expenditure in activity (26% – 30%), in thinking, and even in digesting food (5% – 10%).
Thus, your total energy expenditure combines the two: your energy expenditure at rest plus your energy expenditure in other activities.
How we arrived at a number
The estimated daily caloric intake needed for an adult female of 60 kilos varies between 1, 600 and 2, 400 heat rías per day.
For a man of 70 kilos, needs Daily calories can range from 2000 and 3000 calories per day.
That is around 25 – 30 calories per kilogram of body weight.
Instead, young children burn around 120 calories per kilo of weight per day.
This ratio decreases continuously as the child grows.
So, young children have the metabolism highest of all . This extra calorie requirement is necessary for growth.
So, if two women of the same weight may have caloric needs that vary by up to 34%, does that mean that the woman whose body consumes more calories has a faster metabolism than the woman whose body uses fewer calories?
Not necessarily.
A woman could spend more of her day physically active and therefore would need for example more energy to walk to work and for her kickboxing class afterwards.
Beyond those basic guidelines, there are many ways to estimate total and resting energy expenditure if you want to understand your body’s specific caloric needs.
A common and easy method is to use predictive formulas such as the Mifflin-St equations. Jeor or Harris-Benedict which are based on your age, height, weight and gender to determine how much energy your body needs to be alive.
To calculate total energy expenditure, you must also add the activity factor.
The indirect calorimetry is another way of estimating metabolic rate.
Energy expenditure is calculated by measuring the amount of oxygen used and the carbon dioxide released by the body.
Your body depends on oxygen for perform all its metabolic functions.
For every liter of oxygen you use, you spend approximately 4. 82 energy calories from glycogen or fat.
Indirect respiratory calorimetry is normally performed in a doctor’s office, although smaller, more portable and more affordable devices are increasingly being marketed.
Factors that influence metabolic rate
Metabolic rate and caloric requirements vary from person to person depending on factors such as genetics, sex, age, l a body composition and the amount of exercise you do.
The state of health and certain medical conditions can also influence in metabolism. For example, a regulator of metabolism is the thyroid gland, located in the front of the neck, just below the Adam’s apple.
The more thyroxine a person’s thyroid gland produces, the higher their basal metabolic rate.
The fever can also affect a person’s basal metabolic rate.
For every increase in 0.9 degrees Fahrenheit (0.5 C) in a person’s internal body temperature, their basal metabolic rate increases by approximately 7%.
Other medical conditions that influence basal metabolic rate may include muscle wasting (atrophy), prolonged starvation, low oxygen levels in the body (hypoxia), muscle disorders, depression and diabetes.
Another important factor is the composition of the Body. For example, an overweight woman with a body composition of 40% body fat and about 40 kilos of muscle mass, you will burn fewer calories while resting than a woman with a 34% body fat and 57 kilos of muscle mass, since the muscle tissue in the body is more metabolically active than fatty tissue.
This is also the reason why the basal metabolic rate decreases with age.
As people get older, they lose or generally muscle mass and fat tissue gaining, which equates to a decrease in basal metabolic rate of approximately 1% to 2% per decade.
If you really want to give your metabolism a boost, the easiest way to do it is to increase your muscle mass and your activity level.
By increasing muscle mass, you will also increase the basic amount of calories needed to maintain those muscles.
Instead of complaining about having a slow metabolism, you can try speeding it up to make it at least a little faster.
This article was published on The Conversation and reproduced here under the Creative Commons license. Click here to read the original version.
Terezie Tolar-Peterson is a professor of Food Sciences or n, Nutrici or ny Promoc ion d e Health from Mississippi State University, in the United States.
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