The Basics of Metabolism and Weight Loss
We all know the word metabolism, but what does it really mean? The average person might define metabolism as the process of breaking down food. That is partially true, but it’s actually much broader than that. You see, metabolism is essentially the collection of all the chemical processes in your body that keep you alive, which includes the conversion of food into energy.
The three main functions of metabolism are the conversion of food into fuel, the conversion of food into cellular building blocks, and the removal of metabolic waste.
Food to Fuel
The two major sources of fuel our body uses are carbohydrates and fat. Carbs get a bad rep these days, but they are essential for a healthy and well balanced diet (especially so if you are an athlete). See, your body prefers to use carbs as its source of energy for all high intensity activity. This includes but is not limited to: weight lifting, sprinting, cross fit, HIIT, and so on. Knowing that carbs get broken down in our bodies and converted into sugar (glucose), it’s easy to see why this is the case. If you’ve seen any small child consume way too much candy, you know what happens!
On the other side, we have fat (both dietary and stored). Fat is the body’s preferred energy source for steady, low intensity physical activity such as walking, stretching, sitting, etc. That’s right; your body actually DOES burn fat while you sit on your butt watching Family Feud reruns (assuming your body is functioning normally of course). Fat is digested and absorbed a lot slower than carbs, which is why it provides steady energy over a longer period of time. Think about it: do you get a “fat high” from eating too much fat? Does eating too much fat give you a rush? Do you crash after eating fat? No, no, and no; but ask yourself those same questions about carbs and your answers will be different. See the difference?
While protein can technically be a form of energy by being broken down and converted to glucose, this only occurs during extreme circumstances. Nutritionally, proteins’ primary function is to provide the building blocks for our cellular structures in the form of amino acids. Some proteins function as enzymes and some are involved in cell membrane transport and cell signaling.
Proteins are broken down into their monomer units called amino acids. Amino acids are involved in the construction and reparation of cells and tissues, which is crucially important for people who lead active lifestyles. When we exercise, especially with resistance, we actually cause tiny tears in our muscle tissues. These tears get repaired by amino acids. It is through this break down and build up cycle that the body adapts to exercise stimulus. Athletes not only need to consume enough protein for normal metabolic functions, they have to make sure they consume enough extra to provide the necessary nutrition to repair the tears in the muscle.
We all know what metabolic waste is. To put it in poetic words: poop and pee. Any excess of substances that were not metabolized plus metabolic byproducts that cannot be used by the body get excreted out. We are all familiar with this process.
Retention of metabolic waste in the body can be very toxic for you. The body does an amazing job on its own in eliminating waste, but it can only do so much. Our bodies respond to what we put into them, and sometimes the chemicals, additives, and unnatural ingredients we consume can affect our proper digestion. Even if we eat healthy, we can still eat in an unbalanced way that could affect our ability to digest and excrete waste. If you’ve ever noticed that some foods make you bloated, some make you constipated, and sometimes your farts stink a thousand fold more than normal. These are all signs from your body that what you ate was no bueno. Try to avoid foods that you know cause you digestive discomfort.
Metabolism and Weight Loss
So, this is all good info, but what does it have to do with weight loss? Well, all these processes require energy vis-à-vis calories. Our body burns energy to break down food to be used as both fuel and cellular building blocks. It also burns energy through digestion, absorption, and waste elimination. Your body burns energy just to maintain being alive, and it burns energy for physical activity. The cumulative energy burned from all these activities is called our total daily energy expenditure (TDEE).
Knowing your TDEE is crucial for weight loss. It tells you just how many calories you need to consume a day to lose weight. Remember the universal weight loss equation.
Before we wrap up, let me make a quick distinction. Your TDEE is based on your basal metabolic rate (BMR), which is essentially the energy burned by your body while at rest and doing nothing. TDEE is determined by multiplying your BMR by an activity factor, depending on your level of exercise. Naturally, your BMR will be much lower than your TDEE. I do not recommend eating LESS than your BMR. Your BMR should be the absolute minimum calories you need to consume in a day. For healthy weight loss, eat roughly 20% less than your TDEE.
Understanding the basics of energy expenditure and how the three major macronutrients are used by the body is an important step towards conscious and deliberate eating. Always remember that your body is an adaptation machine and will always respond to how you treat it. Fully understanding how your body adapts to stimuli is essentially the goal for all who want to take charge of their health and physique.