If we look at our body, it is made mostly out of proteins and fats. Starting from the membrane of the cell to the hormones to the enzymes to the brain to the skeletal muscles to the hair to the nail, some of them are made of fats and some of them are made of proteins.
But we have 3 macro nutrients available when it comes to nutrition i.e., Carbohydrates, Proteins and Fats.
Now let us understand the role of each of the macro nutrient in our body.
- Building and repair of the body
- Enzymes are made up of proteins
- Hormones like insulin, glucagon, thyroid are made up of proteins
- The substance which carries fat throughout the body know as lipo proteins, they are also made up of proteins
- Muscles and bones are made up of protein
- 1 gm of protein can provide 4 kcal of energy
- Cell membrane constitutes of phospholipids and cholesterol
- Myelin sheath, which is the outer covering of a nerve cell also consists of phospholipids
- The fat soluble vitamins A,D,E,K will function only in the presence of fat inside the blood specifically cholesterol.
- Sex hormones are made up of fats
- 1 gm of fat can give 9 kcal of energy
1 gm of carbohydrates can give 4 kcal of energy – That is it, carbohydrates have only one function which is to convert into glucose and provide the body with energy. But as we have seen, energy can be derived from fats and proteins as well. We don’t require carbohydrates for energy. Then do we even need to ingest carbohydrates? That must be the question. The answer is that the body actually does not need carbohydrates to function. It however requires glucose which can be derived by proteins and fats.
There are other benefits of not eating carbohydrates as well like less of insulin spike hence less of fat storage (lipogenesis) and more of fat break down (lipolysis), decrease in cravings, more satiety, less of gastric issues and bloating etc.
Now, it does not really matter how much calorie is going in everyday and how much you are burning as long as you eat the right kind of foods because every calorie is different. If you eat just carbohydrates all day, you are going to gain fat but if you replace it with fats and proteins and equate to the same amount of calories as carbohydrates, you will not get fat. You can try this on yourself and see the result.
When we say fat loss, what we mean is that somehow we want to make use of the fat which is already stored inside the body. We want to create an environment where the fats from the fat cell gets broken down and mobilized so that it can be used up by cells to generate energy. To create such an environment all we need is to not spike the insulin. We can achieve that by reducing the amount of carbohydrates that we eat and increase the amount of fat and proteins.
Another way is to increase the basal metabolic rate of the body. Basal metabolic rate also known as the BMR is the amount of energy which the body expends to function normally when at rest. If we can somehow increase the BMR, the body will start using more energy and that will also help in oxidation of the fat cells to produce energy through one of the pathways known as the aerobic pathway.
We can increase the BMR by increasing the size of the skeletal muscle. Skeletal muscle is a metabolically active tissue i.e., it requires a lot of energy to function and to maintain itself. If the size of the muscle increases, it is going to demand more energy when at rest hence increasing the BMR. To increase the size of the skeletal muscle, you will need to train-eat enough protein-rest.
So, now we know the importance of all the macronutrients and we also know how to manipulate the macronutrients to achieve the goal of fat loss.
I hope I have managed to put across the science in a way which is easy to understand.