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Every little process in our bodies requires energy. When you do a simple movement of an arm, it involves the activity of your brain in making a decision to move, firing signals through neurons, and finally activating muscles, which results in a hand gesture you were trying to make. Some people don’t understand this, but there are millions of cells involved in this, and every single one of them requires energy.
Metabolism represents the reactions that happen in our bodies, and it is defined by two parts. Katabolism is burning of the more complex molecules, during which we get energy, and anabolism represents reactions in our bodies where smaller chemicals are used to create building blocks for our bodies, such as proteins, amino acids, and fats.
We get our energy from food, that is constructed of proteins, carbohydrates, and fats that we burn down or store once they enter our body. The amount of energy that food provides us with is mostly measured in calories. Most energy-related processes happen in the mitochondria, and that’s where it got that nickname “the powerhouse of the cell.”
Most people think that their body and mind are inactive while sleeping, which is not true as our brains are active during sleep, and our body still requires energy to function. During our nightly rest, our brains have a vital mission, to repair everything that went wrong the previous day. That is when our muscles, joints, and vital organs are restored, and it’s one of the reasons why we feel refreshed in the morning.
How Do We Spend Our Energy?
Energy expenditure depends on many factors. It is the highest in newborn babies, as their growth rate is incredibly high. Infants double their size in the first six months of their lives, and at the end of the first year, they grow as much as three times. After that, the growth rate is slowed, and then it bursts again in the adolescence, which affects energy expenditure. The elderly need less energy to maintain their body functions, and this amount starts dropping after 40 years for men, and usually after menopause at about 50 years for women.
The amount of energy spent is also affected by your sex. Males spend 16% more power than females, and that is mostly attributed to different hormonal statuses, and different compositions of the bodies. Energy expenditure depends on metabolism and fitness levels as well. People who have more muscles and less fat spend more energy on average. Muscles burn more calories and require more energy to maintain, so that’s why fit people need to ingest more calories than inactive people. That is part of why men need more energy, as they usually have more muscle, while women have a bit more fat stored on average.
Humans need energy for the following:
- Basal metabolism. It consists of many functions that are essential for life and body integrity, such as cell functioning and repairment, synthesis of different hormones and enzymes and their transport, making of proteins and other building blocks, thermoregulation – maintaining the temperature of the body, uninterrupted work of respiratory and cardiac muscles to create breathing and heart rate, brain function and many more. Basal metabolic rate (BMR) is an amount of energy used for basal metabolism in a certain period. It is measured in a lying state, after 8 hours of rest, and 12 hours of fasting, and while being in a relaxed mental state. All of that is so you don’t use energy on brain activity or digesting, and it is also crucial that room temperature is just right, so you don’t need to spend energy to warm up or cool down. BMR is basically what your body needs to survive without any additional activity, and depending on the age, sex, lifestyle, body size and composition it takes up about 45 to 70 percent of your daily energy needs.
- Metabolic response to food. Eating is essential for our production of energy, but it also requires it for absorption, transport, conversion, oxidation, and deposition. These processes increase oxygen consumption and heat production. Also, response to food increases the BMR for about 10% in the next 24 hours of eating a meal.
- Physical activity. It takes the most energy expenditure after BMR, and it is also the most variable. People perform obligatory and discretionary daily operations. Obligatory ones involve working, going to school, tending to family and home demands, and other needs based on an individual’s social, economic and cultural environment. Discretionary activities are not socially and economically essential, but they are crucial for one’s well-being, health, and overall quality of life. They include exercise and fitness activities, optional tasks that provide more family comfort, as well as activities that provide personal enjoyment, social interaction with friends, and community development.
- Growth. We need the energy to make new tissues and deposit energy in those tissues. In the first few months of baby’s life, as much as 35% of energy is spent on growth and development. That number falls to about 5% at 12 months, and then to 3% during the second year. It is pretty steady from there at about 1-2 percent, with a little peak in the puberty.
- Pregnancy. During this period, extra energy is needed for the developing of fetus, placenta and other maternal tissues such as breasts and fat stores. More energy is also required for the changes in metabolism and increased maternal effort at rest and during various activities.
- Lactation. There are two parts of energy consumption in this case, for the production of milk, and the energy stored in the milk secreted. Part of this requirement can be derived from the fat storages that women obtained during pregnancy.
How Much Energy Do You Spend During Sleep?
At the beginning of sleep research, the idea was that the sleep was a state in which we were inactive, in it passively served to conserve energy. Nowadays, studies are showing something completely different. Our brain is very much active during this period, and it is doing the needed housekeeping. Also, this is the time when our memories and knowledge are consolidated.
We spend 90% of the energy during sleep that we usually spend during the awake resting period, or we spend 0.9 of our BMR. There haven’t been considerable differences observed in energy usage, between different stages of sleep, but there haven’t been too much research done in that area either.
Out of all the energy we use, 20% goes to brain energy consumption. That is an extremely high amount for an organ that is that small. But that shows you how important the central nervous system is, as no function in our body can go without its supervision.
A calorie is a standard energy measuring unit, and it is defined as the energy needed to increase the temperature of 1 kilogram of water for 1 degree Celsius. On average, a 125-pound person spends 38 calories per hour while sleeping, a 155-pound individual spends 46 calories an hour, while a 185-pound person burns around 56 calories per hour. You see that the more you weight, your BMR is higher, and the more energy you need to maintain your body. These numbers might not be correct for everybody, as there are a lot of different factors affecting that other than body weight.
If you spread these numbers to a whole night of sleep, ranging between 7 to 9 hours, you get that a 125-pound person burns 266-342 calories, a 155-pound person burns 322-414 calories, while a 185-pound person spends 392-504 calories each night.
How Much Energy Do You Spend During Different Activities?
Metabolic equivalent (MET) is an objective measure of metabolism rate during some activity compared to a sitting and resting state. The more physical the action, the more energy, and oxygen are used, and the higher the MET will be. Here is the list of some activities, and the energy required for them:
|Activity||MET||Energy usage (Described in calories, for a 30-minute activity for a 70 kg man)||Energy usage (Described in calories, for a 30-minute activity, for a 57 kg woman)|
|Golf (with cart)||2.5||92||75|
|Calistenics (no weights)||4.0||147||120|
|Climbing hills (5kg load)||7.4||272||221|
How to Burn More Calories While Sleeping?
Because you burn fewer calories while sleeping than being awake, some people thought that it would be a good idea to skip sleep and stay awake instead, as that would lead to more calories burned and losing weight. Don’t do this, as it is not good for your health, and it won’t even have the desired effects. Lack of sleep affects leptin and ghrelin, the body’s hormones in charge of hunger. When you are sleep deprived, their production is all messed up, so you will eat more, and you will gain weight. Not only do you crave more food when you are sleep deprived, but you are also more likely to for full of sugars unhealthy meals. Lack of sleep also increases the levels of cortisol, a hormone that is stimulating your body to store more energy as fat.
There are a few things you can do to help boost your metabolism.
- Don’t eat too close to bedtime. It won’t slow down your metabolism, as it is often thought, but it might prevent you from falling asleep, and that affects your metabolism in the long run.
- Consider losing extra weight. Fat burns fewer calories than muscle while resting, so maybe pay a visit to a dietitian to discuss healthy meal plans.
- Exercise regularly. As we said, more muscle means more calories burned, even when you are resting. So aim for 105 minutes of moderate, or 75 minutes of vigorous exercise every week. Also, make sure to increase strength training for the best results. Exercise will also help you sleep better, but make sure that you don’t do it too close to bedtime, as it can make it harder to fall asleep.
- Caffeine might help for more effective training. People who drink caffeinated drinks before going to the gym can usually do more reps, than when they don’t drink it. Be aware, that drinking caffeine later in the day also affects your sleep.
- Don’t use metabolism supplements. These can include some harmful ingredients that might have a counterproductive effect on the weight loss you are trying to accomplish. If your doctor hasn’t prescribed you anything, don’t do it.
- Take regular treatment for your conditions. Certain conditions like hypothyroidism and Cushing syndrome can slow down your metabolism. Make sure to follow your treatment and consult them with any exercise you want to try out.
- Maintain healthy sleep habits. This is very important, so aim to get 7 to 9 hours each night. Also, make sure to make a schedule where you go to bed and wake up every time each day, even during the weekends. Create a quiet, dark bedroom environment, free of any distraction. You should avoid screens before bed, and do something relaxing. You can try taking a hot bath, reading a book, some light yoga, or listening to calming music. Limit your naps to 30 minutes a day, and avoid using stimulants like alcohol and nicotine as they can disrupt your sleep.
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Dusan is a biologist, a science enthusiast and a huge nature lover. He loves to keep up to date with all the new research and write accurate science-based articles. When he’s not writing or reading, you can find him in the kitchen, trying out new delicious recipes; out in the wild, enjoying the nature or sleeping in his bed.