Fat burning: how does it really work?

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Fat burning sounds like something you can master with the right trick, but it’s mainly a matter of understanding your energy balance. In this article, we’ll explain in simple terms how your body burns fat, what really determines fat loss, and where the well-known promises of ‘accelerated fat burning’ fall short. No hype, just clarity.

How does fat burning work in your body?

Fat burning is the process by which your body converts stored fat into usable energy. Whether you lose net fat depends on your energy balance: if, over a longer period, you consume less energy than you burn, your body will draw on its fat reserves.

Your body is constantly drawing energy from a mix of fats and carbohydrates, even right now as you’re reading this. Any energy you consume through food and drink that isn’t used immediately is stored, largely as body fat. If you consistently consume more than you burn, you’ll put on weight. If you burn more than you consume, you’ll lose fat over time. That’s the crux of it: fat burning happens all day long, but losing fat requires a sustained deficit.

How do you lose fat, and what really determines fat loss?

Fat loss is almost always the result of a sustained energy deficit, not a single specific food, type of exercise or quick fix. Anyone who wants to lose body fat simply needs to burn more energy than they consume over a longer period.

This makes the question ‘how do you lose fat’ less dramatic than much of the content out there suggests, but also more honest. A moderate deficit that you can maintain for months works better than a strict diet that falls apart after two weeks. Getting enough sleep, incorporating exercise into your daily routine and following a diet you enjoy will help you maintain that deficit. There is no evidence that a single product can force you to ‘burn fat effectively and quickly’ independently of your overall energy balance.

Do you burn more fat at low or high intensity?

During low-intensity exercise, your body derives a larger proportion of its energy from fat, but during more intense exercise you burn more calories overall. For fat loss over several weeks, that total energy expenditure ultimately carries more weight than the fuel mix during a single training session.

As the intensity of your exercise increases, your body shifts towards burning carbohydrates, as these provide energy more quickly. The point at which carbohydrates take over from fats varies from person to person and depends on your fitness level. The popular ‘fat-burning zone’ is based on that higher proportion of fat at low intensity, but a higher percentage of a small total is still a small number. Both gentle endurance exercise and more intense interval training can contribute to fat loss. The best form of exercise is the one you can stick to regularly and that suits your recovery.

Can your diet influence fat burning?

There is no food or supplement that burns fat for you. Diet mainly influences your fat loss indirectly, via your overall energy balance and how satiated and energised your diet keeps you.

It is true that your body uses relatively more energy to digest protein than it does to digest carbohydrates or fats, a phenomenon known as the thermic effect of food. However, this effect is modest and does not, in itself, burn fat reserves. Claims to ‘stimulate’ or ‘promote’ fat burning with special supplements or diets do not hold water: what matters is a sustainable energy deficit and a diet that helps you achieve it. That may be less spectacular, but it is what the science shows.

What role does protein play in weight loss?

According to the EU register of authorised claims (EU Regulation 432/2012): Protein contributes to the maintenance of muscle mass.

This is relevant because, when you lose weight, ideally you should lose mainly fat and as little muscle tissue as possible. Note the nuance: protein does not ‘burn’ fat and does not accelerate fat loss on its own. If you’d like to read more about why your body needs protein or how much you need each day, take a look at why your body needs protein and how much protein you need each day.

What’s the best way to train for fat loss?

The best workout for fat loss is the one you can stick to and that helps you maintain your muscle mass. Strength training combined with sufficient daily physical activity works well for this, as it increases your energy expenditure and engages your muscles.

It’s a common misconception that only long, low-intensity cardio burns fat. In practice, what matters most is your total level of physical activity, ranging from targeted workouts to everyday activities such as walking and cycling. If you combine your strength training with a sustained, moderate calorie deficit, losing body fat becomes realistic. Consistency over several months is more effective than a single intense week.

Frequently asked questions about fat burning

Is there such a thing as a ‘fat-burning zone’?

At lower intensities, a larger proportion of your energy comes from fat, so in that sense it does exist. But for fat loss over the long term, your total energy expenditure and energy deficit are more important than the fuel mix during a single session.

Do you burn more fat on an empty stomach or at night?

Your body burns fat continuously, even whilst you’re asleep and on an empty stomach. There’s no strong evidence that training on an empty stomach or the timing of your meals measurably accelerates your net fat loss, as long as your overall energy balance remains the same.

Does a protein shake make you lose weight?

No, a protein shake is not a weight-loss product: fat loss comes from a sustained energy deficit. What a shake does do is make it easy to keep your protein intake up while you keep an eye on your energy balance. Protein contributes to the maintenance of muscle mass.

How quickly can you safely lose fat?

For most people, a gradual rate of fat loss is easier to sustain than a strict crash diet. If in doubt, or if you have any underlying health issues, consult a doctor or dietitian, especially if you want to lose a lot of weight.

Easily maintain your protein intake

If you want to easily maintain your protein intake whilst keeping an eye on your energy balance, a protein shake is a practical addition. Our Whey Natural Organic and Vegan Protein Organic (made from fava protein) are certified organic and contain no unnecessary extras. Take a look at the full protein range if you’d like to compare which products suit your routine.

About the author

Lars Blom

Lars Blom is a specialist in food supplements and the founder of Ekopura, a Dutch family business that has been making food supplements and protein powders without unnecessary extras since 2015, for athletes and for every day. He is involved every day in the development, formulation and quality control of the products.

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