Fat loss guide

Losing fat is not as straightforward as people think because it is a complex process that involves various factors, including genetics, hormones, and lifestyle habits. The body’s metabolism is also highly adaptive and can adjust to changes in calorie intake and physical activity levels, making it challenging to sustain weight loss over the long term.

Burning muscles along with fat when on a caloric deficit diet

When cutting down on calories, your body will generally burn both fat and muscle for energy. However, the amount of muscle loss will depend on several factors, such as the degree of calorie deficit, exercise habits, and protein intake.

If you are not engaging in regular exercise or resistance training while cutting calories, your body may break down more muscle tissue to use for energy. This can result in a greater loss of muscle mass and strength.

It is not straightforward, however, as muscle loss during calorie restriction does not necessarily depend on whether or not one is participating in the exercise. In fact, research has shown that even in sedentary individuals who are not participating in exercise, caloric restriction can lead to muscle loss.

There is a study that investigated exactly that, which looked at caloric restriction-induced weight loss, urinary markers of bone turnover, and bone mineral density in premenopausal women

In this study, 25 sedentary, overweight or obese women underwent caloric restriction for 6 months. The caloric restriction resulted in significant weight loss, but also resulted in a significant loss of lean body mass (including muscle mass), as measured by dual-energy X-ray absorptiometry (DXA).

The study concluded that caloric restriction without exercise can result in significant loss of lean body mass, including muscle mass, in sedentary individuals.

It’s worth noting that even though caloric restriction can lead to muscle loss, the amount of muscle loss can be minimized through proper nutrition and exercise(28).

How to prevent excessive muscle loss when on a caloric deficit diet

Minimizing muscle loss during a caloric deficit regimen can be achieved through a combination of proper nutrition and exercise.

1. Resistance training: Engaging in resistance training or weightlifting helps to stimulate muscle growth and preserve muscle mass during a caloric deficit. A study published in the Journal of the American College of Nutrition found that resistance training helped to preserve lean body mass in athletes during a period of calorie restriction (29).
2. Adequate protein intake: Consuming adequate amounts of protein is important for muscle preservation during a caloric deficit. A meta-analysis published in the British Journal of Nutrition found that increasing protein intake was associated with greater preservation of lean body mass during weight loss (30).
3. A slow rate of weight loss: Rapid weight loss can lead to greater muscle loss. A study published in the Journal of Applied Physiology found that a slower rate of weight loss resulted in less muscle loss compared to a faster rate of weight loss (31).
4. Carbohydrate intake: Consuming adequate amounts of carbohydrates helps to fuel workouts and preserve muscle mass. A study published in the Journal of the International Society of Sports Nutrition found that consuming a high-carbohydrate diet during a period of calorie restriction helped to preserve lean body mass in athletes (32).
5. Adequate hydration: Staying hydrated is important for muscle preservation and recovery during a caloric deficit. A study published in the Journal of Strength and Conditioning Research found that dehydration during a period of calorie restriction led to greater muscle breakdown and loss of muscle mass in athletes (33).

In general, a moderate calorie deficit of around 500-750 calories per day, combined with regular exercise and a high protein diet, can help to minimize muscle loss while still promoting fat loss. However, the specific amount of muscle loss will vary depending on individual factors such as age, sex, body composition, and exercise habits.

Energy balance: Calorie in – Calorie out

A calorie is a unit of energy commonly used to express the amount of energy in food or the amount of energy expended during physical activity. Specifically, a calorie is the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius.

When it comes to “calories in” and “calories out,” this refers to the balance of energy intake and energy expenditure in the body. “Calories in” refers to the amount of energy consumed through food and drink, while “calories out” refers to the amount of energy expended through physical activity and bodily functions like digestion and breathing.

To maintain weight, it’s generally recommended that “calories in” and “calories out” are balanced, meaning that the body is burning as many calories as it’s taking in. If a person consumes more calories than they expend, they may gain weight, while if they expend more calories than they consume, they may lose weight. However, it’s important to note that other factors can also impact weight, such as the types of foods consumed, the body’s metabolism, and overall health.

Calorie in (Energy in)

Diet plays a significant role in weight loss and should be tailored to individual needs and preferences. A sustainable and healthy approach to weight loss involves creating a moderate caloric deficit through a combination of diet and exercise, while also focusing on building healthy habits and a balanced lifestyle.

Calorie out (Energy out)

Physical activity could be many things from our bodies’ perspective. Physical activity can help with weight loss by increasing energy expenditure and creating a greater caloric deficit. It is not just exercise, but exercise has the most benefits, such as increasing muscle mass, improving insulin sensitivity, and boosting metabolism, which can help to promote fat loss and prevent weight regain.

During normal activity, the body burns calories to perform essential functions such as breathing, circulation, and digestion. The amount of calories burned depends on factors such as body size, gender, age, and activity level.

During exercise, the body burns calories at a faster rate to provide energy for physical activity. The type and intensity of exercise determine how many calories are burned. Aerobic exercises such as running and cycling burn more calories than strength training exercises such as weightlifting.

Humans burn energy through a process called metabolism, which is the chemical process that occurs within cells to convert food into energy. Calories, a unit of measurement of energy, are burned during this process.

Even those in a coma, or in a vegetative state, despite not appearing active burn through energy, and how much energy is being burned and expelled in the form of carbon dioxide could be indicative of recovery.

Exposure to hot conditions can increase the body’s metabolism and cause it to burn more calories as it tries to regulate its internal temperature. This can lead to dehydration and fatigue if the body is not properly hydrated.

Exposure to cold conditions can also increase the body’s metabolism and cause it to burn more calories as it tries to generate heat. However, prolonged exposure to cold temperatures can lead to hypothermia and other health problems.

Disease and stress can affect the body’s metabolism and cause it to burn calories at a faster or slower rate than normal. For example, an overactive thyroid can cause the body to burn calories at a faster rate, while conditions such as depression and anxiety can slow down metabolism and lead to weight gain.

However, it is important to note that weight loss is not solely dependent on physical activity.

The sequence of filling the energy storage

When we consume food, the energy contained in the macronutrients (carbohydrates, fats, and proteins) is metabolized by the body to produce ATP (adenosine triphosphate), which is the primary form of energy used by cells.

During recovery, the body’s priority is to restore the most depleted energy stores first, while also meeting its ongoing energy needs.

The body refills the storage of ATP (adenosine triphosphate), glycogen, triglycerides, and creatine phosphate in a specific sequence, based on the body’s energy needs and the availability of substrates for energy production.

The order in which the body refills these energy stores after exercise depends on several factors, including the type, duration, and intensity of the exercise, the individual’s diet, and overall health.

The standard sequence of energy storage in the body can be summarized as follows:

1. Carbohydrates are broken down into glucose, which can be used immediately for energy or stored in the muscles and liver as glycogen.
2. ATP is produced from glucose through a process called glycolysis, which occurs in the cytoplasm of cells.
3. If ATP is needed quickly, the body can also use creatine phosphate (CP) as a rapid source of energy. CP is stored in muscles and can be quickly converted into ATP when needed.
4. If glucose and CP stores are depleted, the body will start to break down stored fat (triglycerides) to produce ATP through a process called beta-oxidation. This occurs primarily in the mitochondria of cells.
5. Finally, if energy intake consistently exceeds energy expenditure, excess calories will be stored as fat in adipose tissue throughout the body, primarily as triglycerides.

It’s important to note that these processes are highly interconnected and occur simultaneously throughout the body, depending on the body’s energy needs and nutrient availability.

There will also be individual differences and levels of storage may vary among individuals, for example, muscle and live stores glycogen, the fitter and muscular you are the more glycogen you can store.

The sequence of using the energy storage

The body will go through multiple sources of energy throughout the day and throughout the exercise.

When needed, the body will consume ATP (adenosine triphosphate), glycogen, triglycerides, and creatine phosphate in a specific sequence, based on the body’s energy needs and the availability of substrates for energy production.

1. Creatine Phosphate: Creatine phosphate is the first energy source that is used during short-term, high-intensity activities, such as sprinting or weightlifting. When the body’s stores of ATP are depleted, creatine phosphate donates a phosphate group to ADP to form ATP, providing a quick source of energy. Once creatine phosphate stores are depleted, the body moves on to other energy sources.
2. ATP and Glycogen: Next, the body utilizes stored ATP and glycogen to provide energy for muscular activity. ATP is the immediate source of energy for muscle contractions and is produced through a process called cellular respiration, which occurs in the mitochondria of cells. Glycogen is the stored form of glucose in the liver and muscles and can be broken down into glucose to produce ATP.
3. Triglycerides: After ATP and glycogen stores have been depleted, the body begins to break down the stored fat in adipose tissue to release fatty acids, which can be used for energy. This process is known as lipolysis and typically occurs during low to moderate-intensity exercise, such as walking or jogging. The fatty acids are transported to the working muscles and other tissues to be used for energy.

At the point of burning fat, the body begins to break down stored fat (triglycerides) into fatty acids and glycerol, which can be used as an energy source to produce ATP through a process called beta-oxidation. This occurs primarily in the mitochondria of cells.

As long as the body continues to have an energy deficit (i.e. burning more energy than it’s taking in), it will continue to break down stored fat to maintain energy production.

What are excess calories?

When you consume more calories than your body needs for energy, those excess calories are either stored as fat or burned off as heat. The proportion of excess calories that are stored as fat versus burned off as heat depends on several factors, including your metabolic rate, physical activity level, and the macronutrient composition of the food you eat.

The body’s decision to store excess calories as fat is based on complex physiological and metabolic factors. When we consume food, the body breaks down the macronutrients (carbohydrates, proteins, and fats) into their constituent molecules and uses them for energy and other functions.

The body has a limited capacity to store glucose through glycogen in the liver and muscles. When glycogen stores are full, any excess glucose is converted into fatty acids and stored in adipose tissue as triglycerides. Similarly, excess dietary fat is stored in adipose tissue, which acts as a long-term energy reserve.

However, the body does not have an exact threshold for when to store calories as fat. It is influenced by various factors, including genetics, hormonal balance, and lifestyle habits. For example, insulin, a hormone released by the pancreas in response to high blood sugar levels, promotes glucose uptake and fat storage in adipose tissue. Other hormones, such as leptin and ghrelin, also play a role in regulating appetite and energy balance.

The body also has a metabolic rate, which is the amount of energy it burns at rest and during physical activity. This can vary based on factors such as age, sex, body composition, and activity level. The metabolic rate will also affect how much excess calories are stored as fat.

Metabolical fitness and fat storage

Metabolic fitness is a broad term for the individual’s ability for functional processes around the use, extraction, and storage of energy. But

Metabolic fitness is a term used to describe the body’s ability to efficiently and effectively process nutrients, maintain energy balance, and avoid the development of metabolic disorders such as insulin resistance, type 2 diabetes, and obesity. Metabolic fitness is influenced by a variety of factors, including genetics, lifestyle habits, and overall health status. Key markers of metabolic fitness include measures such as insulin sensitivity, glucose tolerance, lipid profiles, and basal metabolic rate. When a person is metabolically fit, their cells are better able to utilize and dispose of nutrients, resulting in improved energy metabolism and a reduced risk of metabolic disorders.

Individuals who are metabolically fitter are better able to handle excess calories without storing them as fat. This is because metabolic fitness, which is often assessed through measures such as insulin sensitivity, glucose tolerance, and lipid profiles, is closely tied to the body’s ability to effectively utilize and dispose of nutrients.

When someone is metabolically fit, their cells are more responsive to insulin, which allows for efficient uptake and utilization of glucose by the muscles and other tissues. This means that less glucose is left circulating in the bloodstream, where it can be converted into fat if not used for energy. Additionally, a person who is metabolically fit may have a higher basal metabolic rate, which means they burn more calories at rest, making it easier to maintain energy balance and avoid storing excess calories as fat.

On the other hand, individuals who are metabolically unfit may have impaired insulin sensitivity and glucose tolerance, which can lead to higher levels of circulating glucose and insulin. This can promote fat storage and contribute to the development of insulin resistance and metabolic disorders such as type 2 diabetes.

How is food converted into fat? Lipogenesis

When we consume more calories than our body needs, the excess energy is stored as fat in adipose tissue. The process of converting the macronutrients (fats, carbohydrates, and proteins) we consume into fat is called lipogenesis.

The process of lipogenesis differs slightly depending on the macronutrient being converted.

Carbohydrates

Carbohydrates are the primary source of energy for the body, and any excess carbohydrates are stored as glycogen in the liver and muscles. However, if the glycogen stores are full, the liver converts the excess glucose into fatty acids and releases them into the bloodstream to be stored as fat in adipose tissue.

When we consume carbohydrates, they are broken down into glucose, which is used by the body for energy. Any excess glucose that is not needed for energy is stored as glycogen in the liver and muscles. However, once glycogen stores are full, the excess glucose is converted into fatty acids through a process called de novo lipogenesis.

During de novo lipogenesis, glucose is converted to pyruvate through the process of glycolysis. Pyruvate is then converted to acetyl-CoA, which is used in the synthesis of fatty acids. The fatty acids are then assembled into triglycerides, which are stored in adipose tissue for future energy needs.

Proteins

When we consume proteins, they are broken down into amino acids, which are used by the body for various functions, such as building and repairing tissues. However, if the body has more amino acids than it needs for these functions, the excess amino acids can be converted into glucose through a process called gluconeogenesis.

If the body has enough glucose for its energy needs, any excess glucose is converted into fatty acids through de novo lipogenesis, as described above.

Dietary fats

When we consume dietary fats, they are broken down into fatty acids and glycerol, which can be used by the body for energy or stored in adipose tissue. However, the process of converting dietary fat into body fat (lipogenesis) is less efficient than converting carbohydrates or proteins into fat.

Why is dietary fat not as scary as we used to think

Dietary fat is not as scary as people used to believe because research has shown that the type of fat and the overall quality of the diet is more important than the amount of fat consumed.

For many years, dietary fat was demonized as the cause of weight gain, heart disease, and other health problems. However, recent studies have shown that not all fats are created equal, and some types of fat can actually be beneficial for health.

For example, monounsaturated and polyunsaturated fats, found in foods such as nuts, seeds, avocados, and fatty fish, have been shown to improve blood cholesterol levels, reduce inflammation, and lower the risk of heart disease and other chronic illnesses.

Furthermore, a diet high in healthy fats can be more satiating and help to control appetite, making it easier to maintain a healthy weight. Additionally, fat is a necessary nutrient for many bodily functions, including hormone production, absorption of fat-soluble vitamins, and the maintenance of cell membranes.

However, it is important to note that not all fats are healthy. Trans fats, found in many processed foods, have been linked to an increased risk of heart disease, and saturated fats, found in high amounts in animal products and some processed foods, should be consumed in moderation.

Where is the fat stored in our body?

There are differences in the type of fat and where it is stored around the body, these differences are crucial to understanding how metabolically healthy a person is.

Types of fat. Where is the fat stored in our body?

In an average individual, fat can be stored in two main types and locations: subcutaneous fat and visceral fat.

The amount and distribution of fat in the body can be influenced by a variety of factors, including genetics, age, sex, diet, and physical activity levels. However, certain medical conditions can also play a role in the accumulation and distribution of body fat.

Subcutaneous fat

Subcutaneous fat is the fat that is located just beneath the skin. Subcutaneous fat is the one that wobbles on the outside. It is the most common type of fat in the body and accounts for up to 80% of total body fat in adults (4). Subcutaneous fat is stored in adipose tissue, which is made up of specialized cells called adipocytes.

Subcutaneous fat is distributed throughout the body but tends to accumulate in certain areas more than others. In women, subcutaneous fat tends to accumulate around the hips, thighs, and buttocks, while in men it tends to accumulate around the abdomen (5).

While subcutaneous fat is often thought of as “bad” fat, it actually serves several important functions in the body. Some of these functions include:

1. Energy storage: Subcutaneous fat stores excess energy in the form of triglycerides, which can be mobilized and used as fuel when needed.
2. Insulation: Subcutaneous fat helps to regulate body temperature by providing insulation and helping to maintain a stable core body temperature.
3. Protection: Subcutaneous fat provides cushioning and protection to the body’s organs and tissues.
4. Hormone production: Subcutaneous fat produces hormones and other signaling molecules that can affect the body’s metabolism and immune system (6).

Research has also shown that subcutaneous fat may have some protective effects against certain health conditions. For example, a study published in the Journal of the American Medical Association found that individuals with higher amounts of subcutaneous fat had a lower risk of death from cardiovascular disease compared to those with higher amounts of visceral fat (7).

While excess subcutaneous fat can contribute to various health problems such as insulin resistance, type 2 diabetes, and cardiovascular disease, it also serves several important functions in the body.

Subcutaneous fat is considered to be a relatively-good fat, unlike visceral fat.

Visceral fat

Visceral fat is the type of fat that is stored deep within the abdominal cavity, and surrounding organs such as the liver, pancreas, and intestines. Unlike subcutaneous fat, which is located just beneath the skin, visceral fat is not visible from the outside and can only be measured using imaging techniques such as MRI or CT scans.

Visceral fat is metabolically active and produces hormones and other signaling molecules that can affect the body’s metabolism and inflammation levels. Some of the functions of visceral fat include:

1. Energy storage: Like subcutaneous fat, visceral fat stores excess energy in the form of triglycerides.
2. Hormone production: Visceral fat produces hormones such as adiponectin and leptin, which can affect the body’s metabolism and appetite regulation.
3. Inflammation: Excess visceral fat can promote inflammation in the body, which can increase the risk of several health conditions, including type 2 diabetes, cardiovascular disease, and some cancers.
4. Insulin resistance: Visceral fat has been linked to insulin resistance, a condition in which the body’s cells become less responsive to the hormone insulin, leading to high blood sugar levels and an increased risk of type 2 diabetes.

Visceral fat tends to accumulate around the organs in the abdominal cavity, but the amount and distribution can vary among individuals. Men are more likely to accumulate visceral fat in the abdominal area, while women tend to accumulate more subcutaneous fat in the hip and thigh region (5).

Research has shown that excess visceral fat is a strong predictor of several health outcomes, including cardiovascular disease, type 2 diabetes, and overall mortality (8, 9). One study found that individuals with higher amounts of visceral fat had a greater risk of developing type 2 diabetes, independent of other risk factors such as age, sex, and BMI (10).

While some visceral fat is necessary for normal bodily functions, excess visceral fat can have harmful effects on health and increase the risk of several chronic diseases. This is the fat you want less of.

Non-alcoholic fatty liver disease and fat

Non-alcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver. NAFLD is often associated with obesity, insulin resistance, and other metabolic abnormalities. Research suggests that individuals with NAFLD may have a greater amount of visceral fat and a higher waist circumference compared to those without NAFLD (1, 2).

In addition, studies have shown that visceral fat accumulation may play a role in the development and progression of NAFLD. One study found that individuals with higher amounts of visceral fat had a greater risk of developing NAFLD, independent of other risk factors such as obesity (3).

The accumulation and distribution of body fat can be influenced by a variety of factors, including underlying medical conditions such as NAFLD. However, more research is needed to fully understand the complex interplay between body fat and disease.

Fat loss occurs after ATP and glycogen are depleted

Fat loss occurs after ATP and glycogen are depleted. During exercise, the body primarily uses ATP and glycogen for energy. ATP is the immediate source of energy for muscle contractions, while glycogen is the stored form of glucose in the liver and muscles.

When the body’s stores of ATP and glycogen are depleted during exercise, the body begins to break down the stored fat in adipose tissue to release fatty acids, which can be used for energy. This process is known as lipolysis, and it typically occurs during low to moderate-intensity exercise, such as walking or jogging.

During lipolysis, fatty acids are released from adipose tissue into the bloodstream, where they are transported to the working muscles and other tissues to be used for energy. This process can lead to fat loss over time, as long as caloric intake does not exceed caloric expenditure.

It’s worth noting that fat loss is a complex process that is influenced by a variety of factors, including exercise intensity, duration, and frequency, as well as an individual’s diet, genetics, and overall health. While lipolysis is an important mechanism for fat loss, it’s not the only factor that contributes to weight loss or changes in body composition.

Which fat do we lose when exercising?

So, when you “burn” fat for energy, you convert it into carbon dioxide and water, which are then eliminated from your body through your breath and other means. This is why losing weight requires a combination of exercise and a calorie-controlled diet – you need to create a calorie deficit to encourage your body to use stored fat for energy.

When it comes to exercise and losing fat there is a distinction between different types of exercise.

When we exercise, the body burns both subcutaneous and visceral fat, but the proportion of each that is burned can vary depending on the type and intensity of exercise. High-intensity exercise tends to burn more subcutaneous fat, while lower-intensity exercise tends to burn more visceral fat (11, 12).

The sequence in which fat is burned during exercise can also vary depending on the individual’s body composition and the type of exercise being performed. Typically, the body will first burn carbohydrates for energy before turning to fat as a fuel source. Within the fat stores, the body may preferentially burn certain types of fat, such as the more easily accessible subcutaneous fat (13).

In individuals with non-alcoholic fatty liver disease (NAFLD), exercise can be an important tool for improving metabolic health and reducing liver fat. Studies have shown that exercise can help reduce liver fat in individuals with NAFLD, and that the amount of liver fat reduction may depend on the intensity and duration of exercise (14, 15).

One study found that a combination of aerobic exercise and resistance training was more effective than aerobic exercise alone in reducing liver fat in individuals with NAFLD (16). Another study found that high-intensity interval training was more effective than moderate-intensity continuous training in reducing liver fat in overweight and obese individuals (17).

Exercise is very good for us and exercise can be an effective tool for burning both subcutaneous and visceral fat, and can help improve metabolic health in individuals with non-alcoholic fatty liver disease. There are ways to measure the levels and prevalence of visceral fat.

Physical activity outside, in the elements for fat loss

Physical activity and exercise are known to have numerous health benefits, including reducing levels of visceral fat and subcutaneous. However, whether exercising in different temperatures can affect visceral fat loss is still a topic of debate, and further research is needed to fully understand this issue.

The storage of visceral fat around the organs is different from that of subcutaneous fat just below the skin. The location of the fat may be a factor in what fat is being lost when exposed to the elements.

There have been a few studies investigating the effects of exercising in colder temperatures on visceral fat loss. One study published in the Journal of Applied Physiology found that exercising in a cold environment (4°C) increased the rate of fat oxidation compared to exercising in a thermoneutral environment (20°C), suggesting that cold exposure may promote fat loss (21). However, this study did not specifically measure visceral fat loss and more research is needed to determine whether cold exposure has a specific effect on visceral fat loss.

Similarly, there have been some studies investigating the effects of exercising in hotter temperatures on visceral fat loss. One study published in the Journal of Clinical Endocrinology and Metabolism found that overweight women who exercised in a hot environment (33°C) had greater reductions in visceral fat compared to those who exercised in a thermoneutral environment (22°C) (22). However, it is important to note that this study was conducted in a relatively small sample of women and further research is needed to confirm these findings.

While some studies suggest that exercising in colder or hotter temperatures may promote visceral fat loss, more research is needed to fully understand this issue. The most important factor for visceral fat loss is regular physical activity, regardless of the temperature. It is recommended that adults engage in at least 150 minutes of moderate-intensity aerobic exercise or 75 minutes of vigorous-intensity aerobic exercise per week to promote overall health and reduce the risk of chronic disease (23).

How to measure visceral and subcutaneous fat levels

The most accurate way to measure levels of visceral fat is to perform imaging scans such as MRI or CT scans that can directly visualize the amount of visceral fat in the abdominal cavity.

However, measuring waist circumference can also be a useful and inexpensive way to estimate levels of visceral fat. This is because visceral fat tends to accumulate around the organs in the abdominal cavity, and a larger waist circumference can indicate higher levels of visceral fat (18).

Several studies have shown that waist circumference is a strong predictor of the amount of visceral fat present in the body and that individuals with larger waist circumferences tend to have higher levels of visceral fat and an increased risk of associated health problems (19, 20).

Measuring waist circumference is a simple and inexpensive way to track changes in visceral fat levels over time. However, it is important to note that waist circumference measurements may not be as accurate as imaging scans and that other factors such as subcutaneous fat and muscle mass can also affect waist circumference measurement.

How to lose 10 kilos of fat (22 pounds)

The process by which 10 kilograms of fat is converted into carbon dioxide (CO2) and water (H2O) involves a series of biochemical reactions that take place in your body’s cells.

When your body breaks down fat, it combines the fat molecules with oxygen (O2) to produce energy, carbon dioxide, and water. The exact proportions of CO2 and H2O produced depend on the chemical structure of the fat molecule but on average, for every 10 kilograms of fat burned, approximately 84% of it is converted into CO2 and 16% into H2O.

The chemical reaction for the conversion of fat into fat loss that takes place is:

For every 10 kilograms of fat burned, approximately 84% of it is converted into CO2 and 16% into H2O.

Meerman R, Brown A J. – “When somebody loses weight, where does the fat go?”(24)

In short, in order to lose weight, you need to lose it in what you exhale and what you sweat out.

It’s important to note that the conversion of fat into CO2 and H2O is not a one-step process but a complex series of reactions that involve multiple organs and enzymes in the body. However, the net result is the conversion of fat into CO2 and water, which are eliminated from the body through exhalation, urination, and perspiration.

Breathing out and sweating out fat, not calories

Calories burned are a measurement of energy expenditure during physical activity and are often used as a way to estimate the amount of fat that is being burned. However, it’s important to note that the number of calories burned does not necessarily correlate directly with fat loss.

When the body metabolizes fat for energy, it is broken down into carbon dioxide (CO2) and water. The CO2 is then exhaled through the lungs, while the water is excreted through urine and sweat. Therefore, measuring the amount of CO2 exhaled during physical activity can provide a more direct and accurate measure of the amount of fat that is being burned (25).

In fact, research has shown that measuring CO2 production during physical activity can be a more accurate measure of fat oxidation than measuring calorie expenditure alone (26, 27). This is because the relationship between calorie expenditure and fat oxidation can vary based on several factors, including the type of exercise, the intensity of the exercise, and individual factors such as fitness level and metabolism.

However, measuring CO2 production during physical activity is not a practical or feasible method for most people, as it requires specialized equipment and expertise. Therefore, calorie expenditure remains a useful measure of energy expenditure during physical activity and can be used in conjunction with other measures such as body composition and physical fitness to track progress towards health and fitness goals.

Physical activity intensity for fat loss

The average human exhales about 1-1.7 pounds (approximately 500-800 grams) of carbon dioxide on an average day. (The exact quantity depends on your activity level—a person engaged in vigorous exercise produces up to eight times as much CO2 as his sedentary fellow human being.)

Also men, in one study showed that there are gender differences, as the average adult male exhales approximately 742 grams of CO2 per day, while the average adult female exhales approximately 608 grams of CO2 per day.

The rate of fat loss in the form of calorie out and CO2 out are different, however, intensity levels of physical activity have a massive impact on the rate of fat loss.

Physical activity and calorie loss/exhalation rate

A typical human inhales air containing approximately 0.04% carbon dioxide (CO2) and exhales air containing approximately 4% to 5% CO2. The proportion of CO2 inhaled and exhaled is a function of the air composition and the body’s metabolic rate.

During physical activity, the metabolic rate increases, leading to higher rates of oxygen consumption and CO2 production in the body. This results in an increase in the proportion of CO2 exhaled, as the body seeks to maintain a balance between oxygen uptake and CO2 exhalation. This is why the respiratory rate and volume of air exchanged per minute increases during physical activity, to accommodate the increased demand for oxygen and CO2 removal.

The proportion of CO2 in the exhaled air can be measured using a technique called capnography, which involves measuring the concentration of CO2 in the exhaled air with a sensor. Capnography is commonly used in medical settings to monitor ventilation and ensure proper gas exchange during anesthesia or mechanical ventilation.

It’s worth noting that the proportion of CO2 inhaled and exhaled can be affected by factors such as altitude, smoking, and lung function, and can also vary between individuals.

Calories burned per activity

Whilst, more commonly calories burned indicate energy burned and it is a good measure of the effectiveness of fat loss, losing carbon dioxide and water as products of combustion of fat is also interesting and should be looked into. There is not enough research into the amounts of carbon dioxide which is inhaled during exercise but more studies are coming.

Let’s have a look at levels of physical intensity, as well as examples of activities, calories burned per hour, and approximate CO2 exhalation rate for each level:

Level of Intensity	Examples of Activities	Calories Burned per Hour (Based on a 150-pound person)	Air Exhalation Rate (Liters per Minute)
Rest	Chilling and daydreaming	50-80	12-20 exhales per minute (12-20 liters of air)
Rest	Sleeping	50-100
Rest	Sitting	80-100
Rest	Standing	100-150
Light	Walking (2 mph)	200
Light	Walking (3 mph), Cycling at a moderate pace, water aerobics, doubles tennis	320
Moderate	Running (5 mph)	600	40-60 exhales per minute (60+ liters of air)
Moderate	Cycling (10 mph)	400
Moderate	Swimming (slow)	400
Moderate	Sex (preferably very active)	85-250
Moderate	Yoga	200
Moderate	Weightlifting	200-300
Moderate	Dancing	300-400
Vigorous	Running at a fast pace, cycling at a fast pace, playing singles tennis, swimming laps	590-780	40-60 exhales ( up to 100 liters of air)

The amount of carbon dioxide exhaled during these activities can also be expressed as a fraction of the total volume of exhaled air, rather than as a rate of liters per second or minute. The typical fraction of exhaled carbon dioxide (FECO2) is around 0.04, which means that approximately 4% of exhaled air is carbon dioxide. However, during exercise and particularly at the end of it, the fraction of exhaled carbon dioxide (FECO2) rises to around 0.05 – 0.06 , meaning that not only exercise makes you breath out more, it makes you breath our more carbon dioxide relative to the other gases you exhale.

Based on this table, the intensity of physical activity and the calories burned/CO2 exhalation rate are comparable. However, light-intensity physical activity produces half the Carbon Dioxide of moderate physical activity and moderate physical intensity produces about half the carbon dioxide of vigorous/intense physical activity.

This means that one hour walk would equal half an hour of brisk walking, and a 15-minute run at a fast pace. However, there are caveats, such as the recovery rate after physical activity.

Recovery rate with a higher CO2 exhalation rate

The recovery time for CO2 exhalation rate after vigorous exercise depends on several factors, including the duration and intensity of the exercise, the individual’s fitness level, and the presence of any underlying health conditions.

The table does not take into account the recovery rate, because for light physical activity such as walking at a leisurely pace, the breath recovers very quickly after the physical activity, whilst for vigorous activity the body is still working hard to compensate for energy lost by exhaling a lot more. The term “winded” is an example of someone working very hard to restore the pre-physical activity level, which is typically reserved for intense and very demanding physical effort.

In general, it takes around 10-30 minutes for the CO2 exhalation rate to return to pre-exercise levels after vigorous exercise. During this time, the body continues to consume oxygen and produce CO2, but at a reduced rate as the body’s metabolism slows down.

During light-intensity exercise, such as walking for an hour at a leisurely pace, the body’s oxygen consumption and CO2 production are lower compared to vigorous exercise. As a result, the recovery time for the CO2 exhalation rate to return to pre-exercise levels is typically shorter compared to vigorous exercise.

In general, after light-intensity exercise, the body’s CO2 exhalation rate returns to pre-exercise levels within a few minutes of stopping the activity. This is because the body’s metabolism doesn’t have to work as hard to meet the energy demands of light exercise.

It could be argued that physically demanding activity that requires a prolonged period of intense breathing and therefore exhaling of CO2 is metabolically longer-lasting than the physical activity itself.

Burning fat effectively

When you exercise, your body burns calories for energy, which requires oxygen. The more fit you are, the more efficient your body becomes at using oxygen, which means you can burn more calories during exercise. However, this does not mean that your body is producing fewer molecules of CO2 and water.

When you lose fat, the triglycerides in your fat cells are broken down into carbon dioxide (CO2) and water (H2O), which are then exhaled and excreted through urine and sweat. The process of losing fat through exhalation and perspiration remains the same, regardless of your fitness level.

Therefore, being fit actually makes it easier to lose fat through exhalation and perspiration, as your body is better equipped to burn calories efficiently during exercise, and to expel the byproducts of fat metabolism.

However, if the individual is highly trained and accustomed to vigorous exercise, the recovery time may be shorter. Conversely, if the individual is not as fit or has underlying health conditions, the recovery time may be longer.

It’s important to note that the number of calories burned per hour can vary depending on several factors, including body weight, age, gender, and fitness level. CO2 exhalation rate can also vary based on individual factors such as lung capacity and breathing efficiency.

Hydration and exercise for effective fat loss

Hydration is important for effective weight loss for several reasons. First, staying hydrated helps to regulate the body’s metabolism and energy production, which are essential for burning calories and losing weight. When the body is dehydrated, the metabolic rate can slow down, which can lead to fewer calories burned and weight gain.

Second, staying hydrated can help to reduce hunger and cravings. Many people mistake thirst for hunger and end up eating more than they need to, which can contribute to weight gain. Drinking water and staying hydrated can help to prevent this, by keeping the body feeling full and reducing the likelihood of overeating.

Third, staying hydrated is important for maintaining muscle mass and overall health. When the body is dehydrated, muscle function and recovery can be compromised, which can lead to reduced physical activity and weight gain over time. Drinking enough water can help to support muscle function and recovery, as well as overall health and well-being.

Overall, staying hydrated is an important part of any effective weight loss program. It is recommended that adults aim to drink at least 8 glasses (64 ounces) of water per day, or more if they are physically active or live in a hot climate. Drinking water throughout the day and before, during, and after exercise can also help to support weight loss efforts.

We need physical activity and exercise

Exercise provides numerous benefits for the organs, tissues, and cells throughout the body. These benefits include increased supply of nutrients, better waste extraction, and autophagy, among others. Here are some of the ways that different parts of the body benefit from exercise:

1. Heart and circulatory system: Exercise strengthens the heart muscle and improves the efficiency of the circulatory system, increasing the flow of oxygen and nutrients to the body’s tissues and organs. This can reduce the risk of heart disease, stroke, and other cardiovascular conditions.
2. Lungs and respiratory system: Exercise improves lung function and capacity, helping to increase the supply of oxygen to the body’s tissues and organs. This can improve overall health and well-being, as well as athletic performance.
3. Muscles and bones: Exercise strengthens muscles and bones, improving overall strength, flexibility, and mobility. This can reduce the risk of injury and improve athletic performance.
4. Immune system: Exercise improves immune function by increasing circulation and stimulating the production of immune cells. This can reduce the risk of illness and infection.
5. Brain and nervous system: Exercise stimulates the production of neurotransmitters and growth factors, which can improve cognitive function, memory, and mood. Exercise can also reduce the risk of neurodegenerative conditions, such as Alzheimer’s disease.
6. Digestive system: Exercise improves digestion and bowel function, reducing the risk of constipation and other digestive problems.
7. Cellular health: Exercise promotes autophagy, a cellular process in which damaged or dysfunctional cells are removed and replaced with new, healthy cells. This can reduce the risk of chronic diseases, such as cancer, and improve overall health and longevity.

Exercise provides numerous benefits for the organs, tissues, and cells throughout the body. By improving circulation, boosting immune function, and promoting cellular health, exercise can improve overall health and well-being, and reduce the risk of chronic diseases.

Exercise and physical activity keep us smarter for longer, make us happier, and more resilient, and fat loss is a big part of being fit.

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