Understanding Calories and Metabolism


If you realized that your waistline has been getting a little bit wider, probably you will start thinking about cutting back on high-calorie foods. Since eating less would mean less calories intake and less calories intake would mean reduce weight. The thing is, when it comes to nutrients and diets, calorie count doesn’t (really) matter. It is the type of nutrients that goes into our body that matters.

What are calories?

Calories are what we get from the food we eat in the form of stored energy (Potential Energy). Our bodies will turn them into heat energy which then allows us to move, to think and do everything else. This system is called the body metabolic system which we will discuss further later. Calories, by definition, is the unit we use to measure the energy that is produced when we eat food. Scientifically, it is the estimated amount of energy needed to raise the temperature of one gram of water by one degree Celsius at atmospheric pressure.

Where do calories come from?

We get our energy (calorie in food) from the process of breaking down of the three main macro nutrients: Carbohydrates, Fats, and Proteins.

Our body will get its energy mainly from carbohydrates first as it is the easiest to be broken down into glucose, a process which produces energy quickly. Fats and protein are less likely to be used as energy providers as they both are used for other functions in the body. Only, in certain cases where carbohydrates are lacking, then the body will start using fats as the energy provider. It is the same for protein. Our body, especially our brain prefers to obtain calories from carbohydrates too. This shows how important it is to have carbohydrates in our diet. The information that was found regarding this three nutrients is that, “Fat provides 9 calories per gram, while carbohydrates and protein each contain 4 calories per gram” says Erin Coleman, R.D., L.D in her article on Daily Calories & Macronutrients.

What she meant is that:
1g of Carbs = 4kcal
1g of Fats = 9kcal
1g of Proteins = 4kcal

Metabolic Process/Metabolism

Metabolism is a scientific term that describes how the body converts food to energy. It is the term used to describe all chemical reactions involved in maintaining the living state of the cells and the organism. Whether it is for growth, reproduction, repair damage cells, and to respond to the environment, all of them require energy.

According to Dr Ananya Mandal, MD, metabolism is needed for two main processes, Growth (Anabolism) or Breaking down of molecules (Catabolism). Anabolism is the building up of things – The process of building up larger substances from combining smaller molecules through a series of chemical reactions that use up energy. An example would be like how our muscles grew bigger after working out and taking in more food. Catabolism is the breaking down of things – The process of breaking down large molecules into smaller ones through a series of chemical reactions which will then be absorbed into the bloodstream. This process produces energy as well. An example would be how rice is broken down to glucose which will be converted to water, carbon dioxide and ATP with energy.


A calorie is a unit we use to measure when energy is obtained from food. Calorie mostly comes from carbohydrates which mean a good amount of carbohydrate is needed in a healthy diet. It can come from other sources like fat and protein in certain cases like extreme dieting or malnutrition. It is the fuel that keeps our cells and organs alive.

Metabolism is the life force of every living thing. It ensures we get the required energy from nutrients. Without a healthy functioning metabolism, we will not get the required nutrients to stay healthy. It is important to keep our metabolism healthy by taking in the right foods at the right amount. Taking in too little, you will get malnourishment, and if too much you will be exposed to chronic diseases.

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