Body Fat Storage and Burning Mechanism
So you want to lose fat!
This is a two part article in which you understand fat gain, fat loss, and the ways to speedup fat loss.
Fat loss can be hard or easy; which depends on you.
There are lots of diets and workout programs out there that helps you to lose fat. All these programs work on one principle.
Yes you read it right!
That one thing is “calorie deficit”
Those diet and workout programs will work for you, if they can cause a calorie deficit in your body.
While calorie surplus diet can make you fat or help you build muscle depends on whether your exercise or not.
In this article you will learn about
- What is fat and what are the benefits of fat
- Why does your body choose fat as a storage medium
- What leads to fat loss and what happens to fat
What is fat?
Fat is a macro nutrient that is essential for your survival. Fat gets stored inside fat cells or adipose cells in the form of triglycerides.
They serve the purpose of supplying energy when your body is deficit in calories. When your body needs energy the fat cells release free fatty acids into blood. Then transport it to the cells that use it for energy.
90% of fat cells are triglycerides and remaining part contain cellular matter. Cellular matter is essential for its functioning.
Fats get stored beneath your skin. They are also found deep inside and around your internal organs, protecting it. They absorb the shock thus providing a cushion effect in protecting our body.
How fat is stored?
Fats get stored in fat cells which expands when quantity of fat increases. Fat storage mechanism in your body works in two ways.
It comes as direct fat that you have ingested. The fats from foods gets broken down by bile acids to smaller form in intestine.
They gets transferred across intestine to lymph system via a lipoprotein called chylomicrons. It also contains the cholesterol and other fat soluble vitamins in your food.
From lymph system the fat, cholesterol and fat soluble vitamins (via A, D, E, and K) enter the blood stream. It then get transported to various tissues.
Chylomicrons are responsible for transporting fats and fat soluble vitamins from your intestine to various tissues.
Your cells (Except brain cells and RBC) can use fat to release energy. The mitochondria in your cells use oxygen and fat to release energy (ATP) and co2.
Your cells will use this only when they are in need of energy.
Other times fats from the chylomicrons will get transferred to your fat cells. Then chylomicrons return to your liver.
That is one part only.
Your liver can synthesis fat from excess carbohydrate and protein that you have taken.
The excess carbohydrate you taken will get converted into fats (triglycerides) in liver. Then it will be transported to fat cells for storage.
Fats from liver is taken by VLDL (very low density lipoprotein)to fat cells for storage. Fats get absorbed to fat cells and VLDL becomes LDL (low density lipoprotein).
These two mechanisms add fat to your abs and other areas.
Fat cell will increase in size while absorbing the fat.
Do you know what happens when they are stretched to max size? Will it stop absorbing more fat?
When fat cells reach a certain size it releases enzymes (Angiotensin II, prostacylin). these enzymes trigger preadipocytes. These will grow to form a mature fat cell. This process is like hyperplasia as there is an increase in muscle fiber number.
Why does your body choose fat as a storage medium?
You have three options for storage - carbohydrate, protein and fat
Protein is break down into amino acids with which your body builds muscles and tissues.
When your body have excess amount of amino acids, body will use it for energy or excrete the excess amount.
Your body has a mechanism to turn amino acids into fat, but that is a rare case. This study shows that high protein diet help in increasing body weight. That is due to gain in lean body mass.
Why this low amount?
More space will be needed to store the same energy in the form of glycogen than in fat. Three molecule of water is needed to store one molecule of glycogen.
If your body replaces fat storage with glycogen you will be heavy.
Your body Fat can provides double the amount of energy provided by glycogen. So if you want to replace fat with glycogen 20 KG of glycogen will be needed to replace 10 KG of fat (approx value).
Advantage of fat storage: Fat provides double the energy than glycogen and requires less space in storage that adds to overall efficiency.
Types of fat
There are two type of body fats that have different function and role in your body.
The function of these fat cells is to produce heat that helps to keep your body warm. They have blood vessels in them, which gives then brown color.
Brown fat is similar to muscles than like white fat. when activated they burns white fat.
The main role of white fat cells is to store calories as fat. White fat cells in smaller quantity are good for your health.
White fat cells release a hormone called adiponectin that increases the insulin sensitivity of liver and muscles, reducing the risk of diabetes.
When the fat cells become larger or as you get fatty the synthesis of adiponectin will slow down.
Benefits of fat low levels of fat
- Fat act as an insulator and protect your body from cold. The brown fat cells will keep your body warm by generating heat
- Fats help in the absorption and storing of vitamin A, D, E and K. Low body fat can negatively affect the delivery of these nutrients to your organs
- It acts as a shock absorber and protects your internal organs from injury. Visceral fat is found around your organs and it acts as a cushion
- Normal level of body fat can boost your sex drive
Health risk of fat
I am not going to write about the health risk of fats, as you know it better than me. You came here to trim your fat after knowing these risks.
“Normal level of fat is good for your health, but higher levels of body fat will cause heart disease, diabetes, cancer, affect hormone levels and sleep.”
Before we jump on to fat burning, you need to understand the calorie usage.
How do your body use calorie?
BMR + thermic effect of food + NEAT/NEPA = daily energy requirement
Basal metabolic rate [BMR] (65-75%)
Basal metabolic rate is the amount of calorie required for the normal functioning of your body at rest. These functions include blood circulation, brain functioning, pumping of heart ,working of nerves and other organs.
The figure shows the formulae for finding your BMR.
BMR varies from person to person; this study shows that the main factor that affects the BMR is lean body mass. Increase in your lean body mass can increase your BMR.
Thermic effect of food (10-15%)
It’s the increase in metabolism due to the intake of food. It is the amount of calorie that is used during the ingestion, digestion and absorption of food.
Your body has to use energy to absorb nutrients from the food that you have taken.
The energy required for the process will be 5-10% of the calorie in the ingested food.
If you take 2000 calorie in a day then your body will spend 100 to 200 calories in the process of absorption and digestion.
You can increase your overall energy expense if you increase your TEF and will be beneficial if you are looking for fat loss.
You can increase your TEF with a protein rich meal. Your meal composition (carbohydrate, fat and protein) is an important factor affecting the TEF.
Your body will burn 25% of energy in protein after its consumption in the process of absorbing. But in case of carbohydrate and fat it is 6% and 4% respectively.
You meal pattern can affect your TEF; a meal pattern is the number of meals you have in a day and the timing of meal. An irregular meal patter n (3 meals yesterday, 4 today, 6 or 3 tomorrow) may decrease your thermic effect of food. In long term this will cause weight gain.
If you are lean your TEF will be higher, this study shows that lean people will have higher TEF than overweight people.
For fat loss it’s advisable to take protein rich food and stick to a regular meal pattern.
Energy expense due to physical activities (15- 50%)
It’s the energy burned while you are exercising.
Exercise will increase your metabolism, this study shows that your metabolic rate will be decreased when you stop exercise.
As you know exercise will affects your muscles; but these studies show that is also affects your fat cells.
When your fats get trained it will become browner and metabolically active.
NEAT and NEPA
Non-Exercise Activity Thermogenesis or Non-Exercise Physical Activity is the energy expense during your normal life activities (walking, cleaning etc).
According to Dr. Levine,
“You can expend calories in one two ways. One is to go to the gym and the other is through all the activities of daily living called NEAT (Non-Exercise Activity Thermogenesis). It appears that NEAT is far more important for calorie-burning than exercise in nearly everyone.”
These activities can contribute as little as 15% to 50 % of your daily energy expense. But this greatly depends on your activity level.
This study shows that NEAT could be a critical component in maintaining your body weight, weight gaining, or losing fat.
Non exercise activities can be done throughout the day. You can stand instead of sitting, stand and walk every one hour at office (if possible). Take the stairs whenever possible.
When your goal is fat los give more importance to NEAT activities than exercise.
Studies shows that exercise will make you eat more to compensate the calories you burn or it can make you to move less. This may negatively affect your weight loss goal.
Do you think why I wrote about calorie burning process?
It helps you to understand various methods by which your body spends calorie. This will come handy when you were planning to loss fat.
Fat loss and gain are the result of calorie deficit and surplus.
Now you know how your body stores fat and the calorie burning process. Let’s look at the fat burning process.
Do you know how your body burn fat and what makes it to do so?
Fat storing and loss can be seen as a bank deposit. If you have surplus money you will deposit in bank and will take it when in need.
Similar way your body will fill its fat stores when there is calorie surplus, i.e. when calorie intake exceeds calorie expense.
When your body spends more calorie than its intake, it has to use pull energy from energy stores to function.
You have stored glycogen in liver and fat in fat cells. When your glycogen stores are depleted, your fat stores will be used to fuel the cells.
This in long term will cause fat loss and transformation.
When you take less calories than you were using, you will be in a calorie deficit condition.
Under such condition your organs and glands will secrete various hormones that acts on liver and fat cells to reverse the energy storing process.
The first process start in liver, glycogen will undergo glycogenolysis and form glucose which will be taken by blood to cells.
Next your body will hit its richest energy reserve; the fat cells.
The fats in fat cells will be broken down to fatty acid and glycerol by lipase.
The lipase will be activated when your body needs to mobilize its stored energy. Adrenaline, adrenocoticotropic hormone, and other hormones are secreted when there is a deficit in calories. Lipase will be activated by these hormones.
Free fatty acids will be released into blood and taken to tissues to use it for energy. Lipoprotein lipase will take fatty acids to get inside mitochondria to use it as fuel.
Thus energy deficit will cause release of certain hormones which act on lipase in fat cells to break down fats into free fatty acids. These fatty acids are taken to cells and are used by mitochondria to power your cells.
The release of fatty acids can make your fat cells shrink in size. This in long term can make you look leaner as you were losing fat.
What happen to fat when its used as fuel?
What you think:
I came to know about the fate of fat from this article on sciencealert.com; before that I don’t even think about it.
This study has been conducted to find out the fate of fat when metabolized.
Study reveals that 10 KG of fat will require 29 Kg of oxygen to oxidize and the byproducts will be 28Kg of carbon dioxide and 11 Kg of water.
C55H104O6 + 78O2 —> 55CO2 + 52H2O + Energy
Carbon dioxide will be exhaled through breathing into atmosphere.
The water will be disposed in the form of urine, sweat and other body fluids.
Body Fat Storage and Burning Mechanism Infographic
You have understood the conditions that will cause your body to store fat and the process by which you can reverse the whole process.
When your calorie intake exceeds calorie out; your body will store fat and when calorie out exceeds calorie intake you will start losing fat.
Next article will be about practical steps in fat loss; ten steps that help you to keep your body in a calorie deficit state.
Hope you like this article; please share your thoughts about fat loss in the comments section.