Why does your body burn several thousand calories a day even if you do nothing but running a kilometre burns less than 100 calories?

Picture your body as a bustling city. You have the energy plant (your metabolism), the waste management system (digestive and excretory systems), the communication network (nervous system), and so many other departments all working together 24/7 to keep the city running smoothly. Just like a city, your body requires energy to function—even when it appears to be doing “nothing.”

Basal Metabolic Rate: The Energy Plant’s Idle Mode

First off, let’s talk about the Basal Metabolic Rate (BMR), which is like the idle speed of your body’s “energy plant.” BMR is the number of calories your body needs to maintain basic functions while you’re resting. This includes breathing, circulating blood, and regulating your body temperature—things that happen all day, every day, whether you’re awake, asleep, sitting, or standing. These activities account for about 60-70% of your daily calorie usage. Shocking, right?

Internal Processes: The Hidden Energy Hogs

You might think physical exercise is the big energy burner, but a lot of your daily calorie budget goes toward internal processes you don’t even realize are happening. For example, your brain uses about 20% of your daily energy just for thinking, regulating emotions, and other cognitive functions. Then there are activities like eating, which kicks your digestive system into gear, using energy to break down food and absorb nutrients. These all add up and operate around the clock.

Exercise: A Drop in the Bucket?

When you run a kilometer and feel exhausted, you might think you’ve burned off a ton of calories. However, the number is usually less than 100 calories, depending on your weight and speed. You might wonder, “Why so little?” Well, physical activity is just a small portion of your total daily energy expenditure. Your body is already busy burning calories for all its other functions, so the added energy needed for running is not as much as you might expect.

Adaptability: Your Body’s Energy-Saving Mode

It’s also worth noting that your body is remarkably adaptable. When you exercise regularly, your body becomes more efficient at using energy, just like a car that gets better gas mileage. This efficiency is great for long-term health but means that each individual activity may burn fewer calories than you’d think.

The Grand Picture: A Day’s Work in Calories

So, when you consider that your body burns several thousand calories a day, remember it’s not just sitting there idly. It’s running a complex, finely-tuned machine that requires constant energy. When you add in a run, you’re simply tacking on some extra work for your body—like asking a busy city to also host a parade. Sure, it requires more energy, but not an overwhelming amount compared to everything else that’s going on.

Isn’t it amazing to think that every single moment—whether you’re asleep, eating, or just reading this—you’re burning calories? Your body is always in motion on the inside, always working, even if you’re not lifting weights or running around a track. So, the next time you wonder about the calories you’re burning, remember: your body is already a calorie-burning champion, simply by doing its daily job of keeping you alive and well.