Losing weight is a frequently discussed topic, with so many different opinions on how it actually works. Over the last few decades, diets have become increasingly popular with low-fat, low-carbohydrate, no-carbohydrate and even liquid diets being implemented. Even more recently, aides such as fat-burning machines and fat loss pills are being incorporated into daily life in the hopes of slimming down.
But if we look at weight loss physiologically, there is a simple equation to follow: our energy in must be less than our energy we are burning off. If someone consumes less energy in through their food and drinks, than their body expends through metabolic processes and movement, then they will lose weight. This is because the demand in energy from our physical activity and bodies’ processes will be higher than what our intake provides, and so we will need to use stored energy from fat or carbohydrates to meet the requirement. On the other hand, if our bodies consume more energy than is able to be burned off, this energy remains in our bloodstream and consequently has to be stored in our cells. This is the process of weight gain.
So now we understand the basics of weight loss and weight gain, let’s look at how our bodies physiologically undergo these changes.
So how do we get fat?
When we digest fat, it gets broken down and transported through the bloodstream as a substance called free fatty acids. Since our bodies are extremely efficient at storing fat through a process known as lipogenesis, these free fatty acids head straight for the fat cell. But before they can be stored in the fat cell however, three of them must first join with one glycerol molecule to form what is known as a triglyceride molecule. The enzyme insulin then acts a key that unlocks the door to the fat cell to move triglycerides into it, and through the assistance of a hormone called lipoprotein lipase (LPL), the triglycerides are more easily moved inside the cell.
Now fat cells which are also referred to as lipids or adipocytes, can best be thought of as balloons. If the balloon is flat and there is nothing in the cell, then we cannot see it. But if we continue to store fat, that is, if we keep inflating the balloons with more triglyceride molecules, then they have the amazing ability to grow and grow. However, in extreme cases the body has the ability to germinate or activate minute, baby fat cells that previously had no ability to store fat, and allow them to similarly start filling up with fat. This only occurs when all of the fat cells in your body have reached or are close to reaching capacity, and hence enables the human body to have no limit on the amount of fat it can carry. In fact, there are about 40 billion fat cells in the human body, with someone who is obese or very overweight having up to around 100 billion.
And how do we lose fat?
Now we know how fat enters our bodies and is stored, let’s look at how we lose fat. Firstly, when we experience stress, an internal response to an external factor, our bodies release chemicals such as catecholamines and adrenaline from glands into our bloodstream. This triggers the opening of the fat cell, and then with the assistance of hormone-sensitive lipase (HSL), fat leaves the cell in a process called lipolysis. Here the triglyceride molecule is broken back down, and the free fatty acids enter the bloodstream where they are able to be used as a source of energy in the aerobic energy system.
It is important to note that if the fat is to go through this whole process of leaving the fat cell, entering the bloodstream and getting ready to be used as a source of energy, then we need to actually use that energy to burn off the fat. Otherwise, one of two things will happen:
We will retain the fat, leading to a higher concentration of free fatty acids in our bloodstream which can clog our arteries.
The process of lipogenesis (fat storing) will start again with the same molecules that have just left the fat cells.
Both of these are becoming more common today as the general population becomes more sedentary. As well, rather than experiencing stress and following it with physical activity like back in the hunter gatherer days, today people tend to combat stress with sedentary activity such as watching a movie, or going to dinner. This prevents the fat-burning process from working as it should.
So, make sure you move your body everyday to keep that fat off, and keep your arteries healthy… and move it some more to deflate those existing fat cells you have. Remember weight loss is achieved by burning more energy than you take in, so perform some physical activity anywhere from walking the dog, playing sports or completing a huffy-puffy workout. Find an activity that you enjoy and keeps you motivated to MOVE!
DID YOU KNOW?
Other than overeating, there are three main times in your life that determine how many fat cells you have in your body. This first is in the third trimester of pregnancy, during which you obviously have no control over your added fat. The other times are in the first year of life and during adolescence due to the growth spurts.