Energy balance is central to our survival. It is what constitutes whether we lose, gain or maintain weight. We can manipulate this balance to our benefit, or alternatively to our detriment. We will run through the principles governing energy balance, what makes a calorie a calorie and the basic fundamentals of energy balance.

Energy, Thermodynamics and Other Simple Concepts.

Energy is defined in science as the “ability to do work”. It’s what drives us, moves us and keeps us alive. You need energy to live. We can get energy from food. Energy in food is measured in kilocalories (calorie for short) or joules (J). 1 kilocalorie equals 4.18 joules. As we are not Amish, we will refer to energy in food in terms of calories.

“Energy cannot be created nor destroyed, but converted from one form to another”.

Ah yes, the fundamental law of thermodynamics. Nice and straightforward.

In essence, this means that we cannot produce energy ourselves, but we can get it from somewhere else. For us, its through food. We also cannot use up energy. What does this mean? You cannot “kill fat”, contrary to the marketing of many fitness programmes. When you exercise, you “use” energy, but you don’t destroy it. We convert food/fat stores into ATP (more on this later), which powers our body. This called energy transfer.

Our body is constantly transferring energy through various chemical reactions. The sum of all of these chemical reactions is called metabolism.

Energy Balance: Who Is She?

Energy balance is the sum of calories ingested in the body through food/drink compared with the number of calories expended through physical activity and physiological processes the body performs to keep you alive.

Energy balance = energy in (calories taken in) – energy out (calories used to power your body).

Variations in energy balance can lead to one of three outcomes:

  1. Positive energy balance: Your energy intake is greater than your energy expenditure. Also called a calorie surplus. Results in weight gain.
  2. Isoenergetic energy balance: Energy intake and output are roughly equal. This is also known as calorie maintenance. This will result in the individual maintaining their current weight.
  3. Negative energy balance: Energy output exceeds energy intake. Known to their friends as a calorie deficit, this will lead to weight loss.

OK Nerd, What Does That Mean For Me?

At it’s simplest level, it makes setting your goals straightforward. To lose weight, you need to be in a calorie deficit. To gain weight, you need to be in a calorie surplus. There is no two ways about it, this is indisputable.

A lot of trainers and coaches will reduce your plan to a simple “just track calories bro”. And at the core, they are not wrong. Manipulating energy balance, also called CICO (calories in, calories out) is the only way to change your body composition. But the human body is a complex structure. Reducing it to “eat less, move more” is not only ignorant, it fails to address the huge variation in individuals.

The amount of calories you need to achieve your goals varies in a number of ways. And, as the following articles will reveal, not all calories are created equal. The next article in this series will discuss metabolism, and the factors that govern your calories in and calories out.

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