Noticed that people with careers related to medicine or biology tend to be leaner? Understanding how fat is stored and burned by the body makes it much easier to know how to control our body fat levels.

Of course, it’s a very complex process and most of us don’t have the time or inclination to take a degree in human biology just to be lean. But that’s OK, you don’t need to understand it on a deep level, just the basic principles will be helpful enough.

The problem is, it’s rare to find an article which explains them in a way most ordinary people can understand… But I’ve gotcha.

How did this fat end up on my body?

When people talk about wanting to lose weight, what they really mean is they want to shed fat, which means they want their body to burn off its fat stores.

Seems simple enough. But how does that work? How does the body “burn off” fat – and where does the lost fat go?


Microscopic fat cells.

When you eat food, you’re taking in energy (usually measured in calories). You also use a bit of energy throughout the day, even doing simple things like walking around the house or pushing a trolley down the aisle at the grocery store. Working out uses up more energy, but works in the same way. As you move, you use up the energy you’ve taken in – the same way any machine uses fuel.

There’s a reason both eating well and exercising regularly are part of a healthy lifestyle: it’s all a matter of taking in energy and using it up. If you take in less energy than you use, you’re at a deficit.

Today’s processed foods are so energy-packed that it has become really easy to take in more energy than we end up using, which means we end up with a surplus.

What happens then?  To get your head around the answer, you first need to understand where the energy you take in via food actually goes.

Energy comes into the body via food & if not immediately needed it's stored as fat Click To Tweet

What happens to the energy you take in?

The energy contained in the foods and drinks you consume either goes straight into your bloodstream for immediate use, or to replenish energy stores in your muscles or, once those stores are full, it gets stored as energy in your fat cells.

At any given moment, you’re both storing and using energy at the same time. The more of a surplus of energy you have in your system, the more energy your body will be working on storing for later in your fat cells.

Think of fat cells as something like water balloons in a bucket. The more excess energy you have, the more balloons you’ll fill up inside that bucket.

Where does fat go when you lose it?

It’s important to remember that your body will primarily use the energy stored in your blood stream and muscles before it starts using significant amounts of the energy stored as fat. Put simply, fat is the last thing your body is going to let go of when you’re using up energy stores.

This is pork fat, but human body fat looks very similar.

This is pork fat, but human body fat looks very similar.

Once your body starts tapping into fat stores, the more energy you use, the more fat you lose. But you don’t actually lose any of the balloons inside that bucket, they just shrink inside the bucket. Meaning that next time you take in more energy than is immediately required they’ll fill on up again.

When you use more energy than you currently have stored in your bloodstream – let’s say you’re working out in the morning and haven’t eaten breakfast yet – your body starts to pull more energy from “storage” (your bucket filled with water balloons).

This is why dieting or fat loss plans of any kind usually involve taking in less energy than you use (no matter how it’s dressed up). When enough energy leaves your cells for your body to use over a longer period of time, your fat cells start to “empty.” An energy deficit is the only way this happens.

When your fat cells empty out – when those water balloons shrink – the fat doesn’t literally burn, but those fat stores do get used as fuel, in a way. The science behind this process is sort of complicated. Eventually, the fat stored in your cells gets broken down into its components – carbon, hydrogen and oxygen. What your body does not use of those chemicals, it gets rid of. You either breathe it out (exhaling carbon dioxide) or excrete it as water (through your urine, sweat, etc.).

Starvation is NOT an effective fat loss strategy Click To Tweet

Fat sort of does get burned off when you lose weight. Just not in the way you probably thought.

But please don’t go thinking that you just need to starve yourself to get rid of excess fat. Not only is this unhealthy and unsustainable, it’s also often ineffective. You see, once the energy supplies in your blood start to run out your body turns to your muscles as an energy source, which can lead to muscle tissue being “burned up” as fuel. This is the last thing you want as not only will it weaken you, it’ll cause your metabolism to slow down, meaning your body burns less energy in the future. Eating plenty of protein-rich foods (meat, fish, eggs, etc.) will help avoid this.

Good eating and exercise, together, burn fat

Empty fat cells.

Empty fat cells shrink, making our bodies slimmer and firmer.

Always keep in mind that eating a healthy diet and staying sedentary probably won’t help you burn much fat.

You actually have to move around and use up good amounts of energy for this process to work.

You also can’t just workout and fill your body up with unhealthy food and expect to burn fat. Healthy portions of protein, carbs and fat, along with a well planned, progressive exercise program, is the most effective way to burn fat and slim down.

Does that take more effort? Of course. But it’s worth it.

For optimal fat loss you need BOTH a healthy diet and an effective exercise program Click To Tweet

Now that you understand how your body burns fat, perhaps you’re a bit more motivated to get to work! Learn the workout techniques that burn fat and get you strong, lean and brimming with energy by joining my Online Gym. Work out from home and gain access to my training guides and hundreds of workout videos and programs, plus tips and support from other online gym members.