The Science Behind Fat Loss: How Your Body Burns Fat

Losing fat is a common goal for many people whether it be for health reasons or body transformation goals. However, the process of how your body burns fat can be difficult if you don’t understand the science behind fat loss. Keep reading as I will explain details from how fat is stored in the body to factors affecting how your body burns fat for you to learn the science behind it and make adjustments for better results.


Definition of fat loss:

As the name says, fat loss is the process of reducing the amount of body fat a person has which can be achieved through a combination of diet, training, and lifestyle changes.
It’s important to know that weight loss and fat loss are not the same as you can lose weight without necessarily losing fat and vice versa. That’s why you need to track your progress in other ways too, not just by weighting yourself.


Importance of understanding the science behind how your body burns fat:

By understanding the science behind how your body burns fat you will be able to make better decisions about your health and wellness goals. This can also help you develop a realistic and sustainable plan for losing fat and maintaining a healthy weight. Without understanding the science behind fat loss, you can easily fall into common myths and misinformation, which can hinder your progress and potentially even be harmful to your health. By understanding how your body burns fat, you can effectively tailor your approach to your specific needs and goals.


How fat is stored in the body:

Fat is stored in the body in the form of adipose tissue, which is a connective tissue made up of cells called adipocytes found all over the body but mostly under the skin. Adipocytes are responsible for storing energy in the form of triglycerides, which are molecules made up of three fatty acids and glycerol. Adipose tissue also plays a role in regulating the body’s metabolism, cushioning, and insulation. Triglycerides can be stored in various places in the body, including:

  • Under the skin (Subcutaneous fat)
  • Within muscle tissue (Intramuscular fat)
  • Around the organs (Visceral fat)


Triglycerides are a type of fat molecule that are stored in the body’s adipose tissue and used as an energy source. As mentioned above they are made up of glycerol and three fatty acids and can be broken down by the body to release energy when needed. Triglycerides are also found in the bloodstream, where they are transported to cells to be used for energy or stored in adipose tissue. High levels of triglycerides in the blood can be a risk factor for certain health conditions, such as heart disease which is something out of this topic.


Factors that affect how your body burns fat:

There are several factors that can affect your ability to lose fat, including:

  1. Diet:

Diet plays a crucial role in fat loss. By now I assume you all know to lose fat, you need to be in a calorie deficit, meaning you need to take in less calories than you burn. This can be achieved through a combination of eating less and/or increasing your daily activity. Choosing nutrient-dense, whole foods and limiting intake of added sugars and unhealthy fats can also support how your body burns fat.

  1. Exercise:

Exercise can help support fat loss by increasing the number of calories you burn during the day. Different types of training can have different effects on fat loss, with some being more effective than others. In general, aerobic exercises, such as walking, running, swimming, or cycling, can be effective at burning fat. Anyhow, strength training is also important as in helps in increasing muscle mass which leads to a metabolism boost.

  1. Hormones:

Hormones play a significant role in the body’s ability to lose fat. Certain hormones, like insulin and leptin, can affect fat storage and metabolism. When these hormones are not balanced it can make it more difficult to lose body fat. On the other hand, Cortisol, which is a stress hormone, can also have an impact on how your body burns fat, as high levels of this hormone can lead to increased appetite and fat storage.
I can easily tell more than 50% of clients who start my coaching and feel stuck in their journey have high levels of cortisol. When we manage to lower their stress and control their cortisol levels suddenly they start to lose fat again and achieve their desired transformation.

  1. Genetics:

Genetics can also play a role in your ability to lose fat. Some people may have a genetic predisposition to carrying more body fat or losing fat more slowly than others. However, genetics is only one factor, and it’s important to remember that lifestyle choices, such as diet and exercise, still have a significant impact on how your body burns fat.


The role of metabolism in fat loss:

Metabolism refers to the chemical processes that occur in the body to maintain life, including the breakdown of nutrients to produce energy. The rate at which these processes occur is known as metabolism rate, or metabolic rate. Metabolism plays a significant role in how your body burns fat, as it determines how many calories you burn during the day. There are three main components of metabolism that can affect fat loss including:


  1. Basal metabolic rate (BMR):

Basal metabolic rate is the number of calories you burn at rest, or the energy required to maintain basic bodily functions such as breathing and circulation. BMR accounts for about 60-75% of your TDEE (total daily energy expenditure). Factors that can affect BMR include age, sex, weight, height, and muscle mass.

  1. Thermic effect of food (TEF):

The thermic effect of food refers to the number of calories your burn to digest, absorb, and process the nutrients in the food you eat. TEF accounts for about 10% of your total daily energy expenditure. The thermic effect of food can vary based on the type and quantity of food consumed.

  1. Non-exercise activity thermogenesis (NEAT):

Non-exercise activity thermogenesis is the energy you expend for activities other than exercise, such as standing, walking, and fidgeting. NEAT can account for a significant portion of your total daily energy expenditure and can vary significantly from person to person. Increasing NEAT through activities such as taking the stairs instead of the elevator or going for a walk after meals can help support fat loss. I recommend you start with 8000 – 10000 daily steps goal.

The role of Hormones in fat loss:

Hormones are chemical messengers produced by the endocrine system that help regulate various functions in the body, including metabolism and fat storage. Imbalances in certain hormones can affect your ability to lose fat. Below is a brief overview of four hormones that play an important role on how your body burns fat:



Insulin is produced by the pancreas and helps with blood sugar regulation. When you eat, your blood sugar levels rise, and insulin is released to help transport the sugar into cells to be used for energy. If you consistently consume a high-sugar diet, you may have chronically elevated insulin levels, which can lead to fat storage and make it difficult for your body to lose fat.



Leptin is produced by fat cells that helps regulate appetite and energy expenditure. It acts on the brain to suppress appetite and increase energy expenditure. When your body becomes less sensitive to Leptin also called Leptin resistance, It can make it difficult for you to lose body fat.



Ghrelin is produced by cells in the stomach that stimulate appetite. High levels of ghrelin can make it more difficult to lose fat by increasing the desire to eat.



Cortisol is produced by the adrenal glands that is released in response to stress. High levels of cortisol can lead to increased appetite and fat storage, particularly in the abdominal area. Chronic stress can lead to consistently high cortisol levels, which can make it more difficult to lose fat.


The role of Exercise in fat loss:

Exercise is an important component to losing body fat, as it can help increase the number of calories your body burns and support overall health and wellness. below you can find different types of exercise that can be effective for losing fat and the importance of building muscle mass in the process.


Types of exercise for fat loss:

Aerobic exercise, such as walking, running, cycling, or swimming, can be effective at burning fat. These types of exercise increase heart rate and breathing, which can help burn calories and improve cardiovascular health.
The sweet spot for targeting fat loss and aerobic health is to adjust your heartrate between 60% – 70% (zone 2).
Strength training, such as lifting weights or using resistance bands by following progressive overload and time under tension, can also be effective at burning fat by increasing muscle mass, which can boost metabolism. High-intensity interval training (HIIT), which involves short bursts of intense exercise followed by periods of rest, can also be an effective way to burn fat but I personally prefer to mix strength training with LISS training rather than HIIT training.

The importance of muscle mass in fat loss:

Muscle mass is important for fat loss because muscle tissue burns more calories than fat tissue, even at rest. Therefore, increasing muscle mass can help boost metabolism and support fat loss. Strength training is an effective way to build muscle mass and combining it with aerobic exercise can be particularly effective for fat loss. It’s important to note that it’s possible to lose fat without necessarily gaining muscle but maintaining or increasing muscle mass can help support long-term fat loss, aesthetics, and overall health.



Fat loss is not just about counting calories as you see everywhere these days. It’s a complex process that is influenced by a variety of factors, including diet, exercise, hormones, and genetics. To lose fat, you need to follow a healthy diet tailored to your body and regular physical activity to promote muscle hypertrophy to transform your body. This approach can also help support overall health and wellness.


Recap of key points:

  • Fat is stored in the body in the form of adipose tissue and triglycerides.
  • Diet, exercise, hormones, and genetics can all affect fat loss.
  • Metabolism plays a significant role in fat loss, and is influenced by basal metabolic rate, thermic effect of food, and non-exercise activity thermogenesis.
  • Hormones such as insulin, leptin, ghrelin, and cortisol can affect fat loss.
  • Exercise, particularly aerobic and strength training, can support fat loss.
  • Genetics can play a role in a person’s ability to lose fat, but lifestyle choices such as diet and exercise can still have a significant impact.


Disclaimer: Individual results may vary:

It’s important to note that individual results may vary when it comes to fat loss. What works for one person may not work for another, and it’s important to find a plan that is sustainable and works for your specific needs and goals.

Interested in learning more about how to effectively lose fat and achieve your health and wellness goals?
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