How the Body Uses Energy | Your Guide to the Body's Fuel Sources

It's no surprise that the body needs energy - and we've all had those days when everything feels heavy and tired, or our eyes just can't stay open. These are the days when we just want to lie on the couch all day long.

Have you ever thought about how the body actually uses energy? So, have you ever asked yourself, for example, "where does the body's energy come from"? Or what are the best foods to boost energy? Well, then you've come to the right place! We're ready to give you everything you need to know about energy!

The body's fuel sources

When we talk about energy, it’s important to first understand where your body’s energy comes from. And you probably already know the right answer – yes, food! But not all foods are created equal when it comes to the energy they provide, so let’s break this down clearly from the start! Dietary sources of energy fit into 3 main categories: carbohydrates, proteins and fats. These are known as our macronutrients, meaning these are the nutrients we use the most and in the largest amounts.

The same amount of carbohydrates and proteins by weight both provide about the same amount of energy each - around 4 calories per gram. Fat, on the other hand, provides a whopping 9 calories per gram. So now you might be thinking - if someone is trying to combat fatigue in their life, then they should just eat more fat, because this will provide twice as much energy! You are not wrong in thinking this way - but you also need to consider how the body is going to use this energy that these 3 different macronutrients give us.

How the body uses energy

Although fat provides the most energy per serving, this does not necessarily mean that it will be used for immediate energy. In fact, carbohydrates are primarily used for quick or immediate energy if this is something we are lacking - for example, the moment you start a jog. This is because carbohydrates are easily broken down into sugars, of which glucose is the body's main fuel source.

Fat, on the other hand, must first be broken down into fatty acids which can then be used as fuel during activities that last for a longer period of time at low to moderate intensity. So now you are probably wondering, can proteins be used for energy? Although proteins can be used for energy to some extent, the main role of proteins is to maintain muscle, aid in growth and repair, help make hormones as well as enzymes - and generally coordinate the body's functions.

How the body uses energy during exercise

Of course, our energy is used differently during exercise - after all, we need that extra push to finish a tough workout or a long hike through the woods! As we've already mentioned, glucose is the most readily available fuel, both at rest and in the early stages of exercise. But our available glucose supply only lasts a short while after exercise has begun, so the body then begins to convert stored glucose (known as glycogen) back into glucose in order to maintain blood sugar levels.

Depending on the type of exercise you do - as well as the duration, the carbohydrate content of your diet can affect how much glycogen your body has stored - which can significantly affect both your training and recovery process. During your workout, fat is also broken down to provide us with energy - thank goodness for that, because as mentioned, glucose stores only last a few minutes after your workout has started.

When fat is used for energy, our stored fat is converted into fatty acids, which are then transported to our muscles for fuel. When it comes to proteins, the body doesn't use this as fuel as often. Proteins are instead used for many of the other tasks listed above. Proteins can contribute up to 5% of the fuel for the body. This usually only happens in certain situations, such as when we haven't consumed enough calories or carbohydrates - then our muscle proteins can be broken down to be used as fuel and energy. Isn't the human body amazing?

4 fun facts about energy

Approximately 50-80% of your daily energy is used when you are at rest. It is exercise and activity that is most often thought of as the main consumer of your body's energy - but it is actually your rest periods that require up to 50-80% of your daily energy supply! Why? In short, the body requires quite a lot of energy to even maintain its vital functions. This includes things like keeping our organ functions running, breathing, for example. Well, we can't expect the heart (a muscle) to work literally 24/7 without a truly solid source of energy! The total amount of energy that is actually used to maintain the body's vital functions varies from person to person, and is called the "basal metabolic rate" (BMR). Factors such as a person's age, muscle mass, genetics, height and weight all contribute to how much energy the body uses at rest.

Just eating uses up valuable energy

Did you know that something as simple as eating uses energy? It's kind of funny to think about, but yes, when we ingest food, our bodies have to use energy to break down that food, extract valuable nutrients from it, and then finally get rid of the unnecessary waste from our bodies. Processing food, extracting nutrients, and removing the waste from our bodies - in total, the entire process of eating, metabolism, digestion, and all - can use up about 10% of our bodies' fuel!

Constant change processes - so make sure your energy comes from nutritious food

The body is constantly building and breaking down through processes called anabolism and catabolism. What this basically means is that the nutrients and energy we take in from food are incorporated into our bodies to help us live. For example, amino acids from proteins are used to make hormones and enzymes to help build and repair tissues. At the same time, stored glycogen, fat, and proteins are broken down into simpler molecules to provide energy, to detoxify chemicals, and to regulate metabolism. The important takeaway from this section is that because the body is constantly changing, the nutrition we consume is essential to ensuring that the right nutrients are in place to support all of these vital processes.

There are 3 main systems of energy

We couldn't spend all this time talking about energy without quickly mentioning the body's 3 energy systems! The energy systems we're talking about refer to the body's different ways of producing energy. The first system is called the phosphagen system, the second is the glycolytic system, and the third is the oxidative system - all of which work together to ensure that we are able to work, move, and generally live our lives. So what and how is it determined which energy system is used? They all actually function as the primary main system - just at different times. The phosphagen system is used mainly during short and explosive activity that lasts about 30 seconds or less. We know, that's not very long - and that's why we have the glycolytic system. This energy system comes into play during activities that last about 30 seconds to 3 minutes - like when you run up a lot of stairs. For activities lasting longer than 3 minutes, the oxidative system (which uses oxygen to produce energy) helps you harness all the energy needed for long workouts and endurance activities.

Best Foods to Boost Energy Levels

Our bodies are amazing at extracting energy and nutrients from food, but some foods are simply better than others at supporting our health. Wondering which foods can give you more energy? Here are some of our favorites!

Nuts and seeds

Our first favorite energy-boosting foods are nuts and seeds. These super convenient and tasty treats are packed with protein, carbs, and healthy fats that help fight fatigue and inflammation in the body - while also providing energy that lasts. Fatty fish (like salmon, herring, and trout) also contain protein and healthy fats like omega-3, which are great for fighting fatigue and overall feeling more energetic! Next on our list are vegetables. The great thing about vegetables is that they are packed with vitamins and minerals that support our enzymes and energy production processes.

Whole grain

Whole grains also make our list of favorite energy-boosting foods due to their high carbohydrate content. However, what's special about whole grains is that they often contain a lot of protein and fiber, which allows for a slow release of glucose into the bloodstream so we don't feel a real sugar crash after a meal.

Water

Even though our next favorite on the list isn't really a food, we couldn't help but mention water. Without water, no life - water is absolutely essential! It's involved in a huge number of reactions and cellular processes - throughout the body, including energy production! In fact, when we're dehydrated, our body processes tend to slow down, leaving us feeling sluggish and tired. So if you need a real boost, water is a great option that can and should be drunk throughout the day!

The body uses energy every second - every day. We need energy to live, and our bodies are incredibly creative and fascinating. The body doesn't just allow us to consume food, it works tirelessly to transform the food you consume into energy so that we can even live and be active every day. Making sure we eat nutritious foods, supporting our systems with clean, safe and effective supplements - and getting regular exercise are all absolutely essential to supporting our energy levels.

So if you are feeling tired and worn out, Aarja Health has a whole collection of energy-boosting supplements of very high quality. So take a look at our webshop! We hope you stay well and healthy!