How is the human body like a car? The answer is that they both need energy. But while a car gets its energy from gasoline, the human body gets its energy from food. When we take in more energy than we use, it gets stored in the form of fat, and this results in weight gain.  

How does food turn into energy? 

As food passes through the mouth into the stomach and intestines, it breaks down into three types of fuel: carbohydrates, fats, and protein. The bloodstream takes up these substances, and delivers them to all the body’s cells, which use them to create energy. Fats provide more energy than carbohydrates, but over a longer period of time.  

Cells prefer to use carbohydrates because they give more short-term energy. If carbohydrate levels are low, or if long-term energy is needed, cells will generally use fats instead. Proteins are used for vital functions and aren’t often used for energy unless both carbohydrates and fats are deficient. Whatever fuel the cell chooses, it is burned to create energy! 

The waste products are carbon dioxide, which is exhaled, and water, which is removed in sweat or urination. 

How can we measure energy? 

The energy produced is measured in the form of calories. We need calories to power our daily activities. The more active we are, the more calories we need. However, the body often has more calories than it can use right away. 

So just like how a car needs a fuel tank, the body needs a way to store energy for later. Some carbohydrates are stored in the liver and muscles. The muscles keep all their carbs for themselves, but the liver releases some when short-term energy is needed.  

But this energy doesn’t last very long. So most excess calories are stored in fat cells. When they store calories, they get bigger, which causes weight gain. This works great for long-term fuel storage. In fact, the reason why these cells can expand so much is because early humans had to go without food for long periods of time. In any case, when the body needs extra energy, calories are released from the fat cells, and they shrink. 

But when the energy stored in these cells is not used, they accumulate in size over time. If they get too big, obesity can result, which has negative health consequences. Excess weight gain is the result of many complex factors, but overall, weight is gained when both the calories consumed and stored by the body exceed the calories used for energy. 

So how do I lose weight? 

For weight to be lost, the body must use more calories than it both consumes and stores, thereby burning the calories stored in the fat cells. We burn a lot of calories just by being alive, but this probably isn’t enough to tip the balance by itself. So to lose weight, there are two things we can do. 

1. We can reduce the amount of calories we eat, to store less energy 

2. We can perform regular physical activity, to use up the stored energy. 

So that’s how the energy from food affects our weight. The body isn’t a perfect machine, but if it’s treated well, you’ll certainly get out more than you put into it.  

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