How The Body Uses Fat As A Fuel For Weight Loss

Jun 6, 202311 min read

Updated: Jan 13

Your complete guide to how the human body uses stored body fat as a fuel for weight loss.

Weight loss specialist at Dennis Romatz Fitness, provides insight into the relationship between body fat as a fuel and weight loss.

When we talk about weight loss, we must first start the conversation with what exactly will leave the body to cause weight loss. The answer is body fat. In this blog, I'll discuss two types of body fat, subcutaneous an visceral and how they are used as a fuel for the body to move and burn calories causing weight loss. I utilize exercise and training protocols targeting both subcutaneous and visceral fat in all of my weight loss training.

1. Subcutaneous Body Fat

What Is Subcutaneous Body Fat?

Subcutaneous body fat refers to the layer of fat that is located just beneath the skin. It is the most visible and accessible type of fat in the body. Subcutaneous fat serves several important functions, including insulation, protection, and energy storage.

This type of fat is distributed throughout the body, but it tends to accumulate in certain areas such as the abdomen, hips, thighs, and buttocks. The amount of subcutaneous fat varies between individuals and can be influenced by factors such as genetics, diet, exercise, hormones, and overall body composition.

Subcutaneous fat acts as an insulating layer, helping to regulate body temperature by providing a buffer against heat loss. It also acts as a cushioning layer, protecting the underlying muscles, bones, and organs from external impacts.

One of the primary roles of subcutaneous fat is energy storage. It serves as a reserve fuel source that the body can tap into when needed. During periods of caloric surplus, when more energy is consumed than expended, excess calories are stored as triglycerides in adipocytes (fat cells) within the subcutaneous fat layer. Then, during periods of energy deficit, such as during exercise or fasting, the body can mobilize these stored triglycerides and break them down into fatty acids to be used as a source of energy.

It's important to note that subcutaneous fat is distinct from visceral fat, which is the fat that surrounds and deposits within the abdominal organs. While both types of fat are important, excessive amounts of visceral fat are associated with a higher risk of certain health conditions, such as cardiovascular disease, type 2 diabetes, and metabolic syndrome.

Maintaining a healthy balance of subcutaneous body fat is important for overall health. While it's natural to have some amount of subcutaneous fat, excessive accumulation can contribute to overweight and obesity, which are associated with various health risks. Regular exercise, a balanced diet, and overall healthy lifestyle habits can help promote a healthy body fat distribution.

How The Body Uses Subcutaneous Body Fat As A Fuel To Move Our Body

When the body needs energy to fuel its activities, it relies on various fuel sources, including subcutaneous body fat. Subcutaneous fat is the layer of fat located just beneath the skin. It serves as an energy reserve that can be utilized when the body requires additional fuel.

The process by which the body uses subcutaneous body fat as a fuel is known as lipolysis. Lipolysis occurs when the body needs to break down stored fat into fatty acids and glycerol to be used as an energy source. This process is regulated by hormones, particularly adrenaline and noradrenaline, which are released in response to various factors such as exercise, stress, and low blood sugar levels.

Once lipolysis is triggered, fatty acids are released from the fat cells into the bloodstream. These fatty acids are then transported to different tissues, including muscle cells, where they are further broken down through a process called beta-oxidation. Beta-oxidation involves the conversion of fatty acids into acetyl-CoA, which enters the citric acid cycle (also known as the Krebs cycle) to produce energy in the form of adenosine triphosphate (ATP).

The energy produced from the breakdown of subcutaneous body fat is used to power various bodily functions, including muscle contractions during movement. During physical activity, the muscles require a significant amount of energy, and the body taps into its fat stores to meet these energy demands. The more intense and prolonged the activity, the more the body relies on fat as a fuel source.

It's important to note that while the body can utilize subcutaneous body fat as a fuel source, it doesn't exclusively rely on this type of fat. The body also utilizes other fuel sources such as carbohydrates and muscle glycogen, depending on the intensity and duration of the activity.

In summary, the body utilizes subcutaneous body fat as a fuel source through the process of lipolysis. Fatty acids released from fat cells are broken down and converted into energy through beta-oxidation, providing the necessary fuel for muscle contractions and movement.

At What Heart Rate Zone And Exercise Intensity Level Do We Burn Subcutaneous Body Fat?

Engaging In Exercises To Burn Subcutaneous Body Fat For Maximum Weight Loss

The concept of heart rate zones and fat burning is a common topic in discussions about exercise and weight loss. It is often believed that exercising in specific heart rate zones can optimize fat burning, including the burning of subcutaneous body fat.

The most commonly mentioned heart rate zone associated with fat burning is the "fat-burning zone," which is believed to occur at a lower intensity of exercise. It is typically considered to be around 60-70% of your maximum heart rate (MHR). According to this theory, exercising in this heart rate zone primarily utilizes fat as a fuel source.

However, it's important to note that the idea of a specific "fat-burning zone" has been somewhat oversimplified. While exercising in the lower heart rate range may predominantly use fat as a fuel source, the total amount of calories burned during exercise is often lower compared to higher-intensity activities.

In reality, the body uses a mixture of carbohydrates and fat as fuel during exercise, and the ratio of these fuel sources can vary depending on several factors, such as exercise intensity, duration, individual fitness level, and overall metabolic rate.

Engaging in higher-intensity exercises, such as those performed in the anaerobic or aerobic threshold heart rate zones (70-85% of MHR), may result in a higher overall calorie burn and can still contribute to fat loss. These higher-intensity workouts may not primarily rely on fat as a fuel source during the activity itself but can lead to greater energy expenditure and potential fat loss throughout the day due to the afterburn effect (excess post-exercise oxygen consumption).

In summary, while exercising at a lower intensity within the 60-70% of MHR range may predominantly use fat as a fuel source during the activity, the overall calorie burn may be lower. Higher-intensity exercise can still contribute to fat loss through increased energy expenditure and metabolic effects. It's important to find a balance that suits your fitness level, goals, and preferences when designing an exercise program. Consulting with a healthcare or fitness professional can help you create a personalized plan based on your specific needs.

Unlike subcutaneous fat, visceral fat is not specifically targeted by heart rate zones or exercise intensity levels. Visceral fat is primarily influenced by overall body fat reduction rather than exercise performed at specific heart rate zones.

When it comes to reducing visceral fat, a comprehensive approach that includes regular physical activity, a balanced diet, and overall calorie expenditure is more effective. Engaging in a combination of cardiovascular exercises, strength training, and high-intensity interval training (HIIT) can contribute to reducing overall body fat, including visceral fat.

Cardiovascular exercises, such as running, cycling, or swimming, can help increase energy expenditure and promote overall fat loss. The intensity of these exercises can vary depending on your fitness level, but incorporating moderate to high-intensity workouts can lead to greater calorie burn and potential reduction of visceral fat over time.

Strength training exercises, such as weightlifting or bodyweight exercises, are also crucial for reducing visceral fat. Building muscle mass through strength training increases metabolism, which helps burn more calories even at rest. This can contribute to overall fat loss, including visceral fat.

Additionally, incorporating high-intensity interval training (HIIT) into your exercise routine has been shown to be effective in reducing visceral fat. HIIT involves short bursts of intense exercise followed by brief recovery periods. This type of training can help increase calorie burn, improve cardiovascular fitness, and promote fat loss.

It's important to note that while exercise is an important component in reducing visceral fat, it should be complemented with a balanced diet and overall healthy lifestyle habits. Consuming a nutrient-rich diet, managing calorie intake, and reducing processed foods and added sugars can further support the reduction of visceral fat.

Remember, targeting visceral fat specifically is not possible through exercise alone. The focus should be on adopting a comprehensive approach that includes regular physical activity, a healthy diet, and overall fat loss to effectively reduce visceral fat over time. Consulting with a healthcare or fitness professional can provide personalized guidance and recommendations based on your specific needs and goals.

Visceral Body Fat

What Is Visceral Body Fat?

Visceral body fat refers to the fat that accumulates in the abdominal cavity, surrounding the internal organs such as the liver, pancreas, and intestines. Unlike subcutaneous fat, which is located just beneath the skin, visceral fat is deeper within the body and is not easily visible.

Visceral fat serves as a protective cushion around the organs and plays a role in maintaining their structure and function. However, excessive accumulation of visceral fat can have detrimental effects on health. High levels of visceral fat are associated with an increased risk of various health conditions, including:

Cardiovascular disease: Excess visceral fat has been linked to an increased risk of heart disease, high blood pressure, and abnormal lipid levels.
Type 2 diabetes: Visceral fat releases certain hormones and chemicals that can interfere with insulin action and lead to insulin resistance, a key factor in the development of type 2 diabetes.
Metabolic syndrome: Excessive visceral fat, along with other risk factors such as high blood pressure, elevated blood sugar levels, and abnormal cholesterol levels, can contribute to metabolic syndrome, which increases the risk of heart disease, stroke, and diabetes.
Certain cancers: Studies have found associations between high levels of visceral fat and an increased risk of certain cancers, including colorectal, breast, and pancreatic cancer.
Inflammation: Visceral fat is an active tissue that produces inflammatory substances. Chronic low-grade inflammation associated with visceral fat can contribute to various health problems, including insulin resistance and atherosclerosis.

Measuring visceral fat accurately requires more advanced techniques than simply measuring body weight or body mass index (BMI). Imaging methods such as magnetic resonance imaging (MRI) and computed tomography (CT) scans are used to assess the amount of visceral fat in the body.

Reducing visceral fat involves adopting a healthy lifestyle, including regular physical activity, a balanced diet, and managing stress. Incorporating aerobic exercise, strength training, and high-intensity interval training (HIIT) can help burn overall body fat, including visceral fat. A diet that focuses on whole foods, adequate protein intake, and controlled calorie consumption can also contribute to reducing visceral fat.

It's important to note that everyone's body composition and fat distribution are unique, and the impact of visceral fat on health can vary among individuals. Consulting with a healthcare professional can provide personalized guidance on managing visceral fat and improving overall health.

At What Heart Rate Zone And Exercise Intensity Level Do We Burn Visceral Body

Fat?

Engaging In Exercises To Burn Visceral Body Fat For Maximum Weight Loss

Engaging in exercises can contribute to the reduction of visceral body fat along with overall weight loss and improved health. While there isn't a specific exercise that exclusively targets visceral fat, a combination of aerobic exercise, strength training, and high-intensity workouts can be effective in reducing overall body fat, including visceral fat. Here's how you can incorporate exercises to help burn visceral body fat:

Aerobic exercises: Cardiovascular exercises, such as running, cycling, swimming, or brisk walking, are effective for burning calories and promoting fat loss. Aim for at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity per week. This can be spread across several sessions.
High-intensity interval training (HIIT): HIIT involves alternating between short bursts of intense exercise and periods of active recovery. HIIT workouts are known to increase calorie burn, improve cardiovascular fitness, and potentially contribute to fat loss, including visceral fat. Include HIIT workouts in your routine, such as sprint intervals, circuit training, or HIIT classes.
Strength training: Resistance training exercises, such as weightlifting, bodyweight exercises, or using resistance bands, help build muscle mass. Increased muscle mass raises metabolism, leading to greater calorie burn even at rest. Incorporate strength training at least two to three times per week, targeting major muscle groups.
Compound exercises: Incorporate compound exercises that engage multiple muscle groups simultaneously. Examples include squats, lunges, deadlifts, push-ups, and rows. These exercises are more metabolically demanding and can contribute to greater calorie burn and fat loss.
Circuit training: Combine strength training and cardiovascular exercises in a circuit-style workout. Perform a series of exercises back-to-back with minimal rest in between. This approach keeps the heart rate elevated, promotes calorie burn, and can contribute to overall fat loss.
Active lifestyle: In addition to structured exercise sessions, prioritize an active lifestyle. Incorporate activities like walking or biking instead of driving, taking the stairs instead of the elevator, and engaging in recreational activities that involve movement. These habits contribute to increased daily calorie expenditure.

Remember that exercise alone may not be sufficient to reduce visceral fat. It should be complemented by a balanced diet, calorie control, and overall healthy lifestyle habits. Consistency, patience, and adherence to a well-rounded approach are key to achieving sustainable results.

It's always recommended to consult with a healthcare professional or a certified fitness trainer to develop an exercise plan tailored to your individual needs, fitness level, and any underlying health considerations.

At Dennis Romatz Fitness, I specialize in sustainable weight loss using exercise protocols that keep my clients in the appropriate heart rate zone and training intensities that tap into primarily subcutaneous fat burning as most humans carry more quantities of subcutaneous fat than visceral. However, all of my weight loss personal training involves, to a degree, training intensities for both subcutaneous and visceral fat burning. Interested to learn even more? You can visit my weight loss page to find more invaluable weight loss information.

About the Author:

Dennis Romatz is a certified personal trainer in Chicago in the downtown Chicago Lakeshore East neighborhood providing personal training scheduled at your convenience at apartment & condo gyms, and in-home. Tailored training programs are designed to meet your individual needs & goals and guaranteed to get you in the best shape of your life in 3 months or less or your money back. Dennis has been recognized as "one of the 20 best personal trainers in the world" by The Institute of Personal Trainers. You can contact Dennis to train with him in person or live online or connect with him on Facebook, Twitter, LinkedIn and Instagram.