Resting Energy Expenditure: What you need to know

Resting Energy Expenditure: What you need to know

Feb 2022
Resting Energy Expenditure: What you need to know

<text-size-medium>Just because your not working out doesn’t mean your not using energy. Discover the role Resting Energy Expenditure plays on your daily goals. <text-size-medium>

Let's start with the basics. What is resting energy expenditure (REE)? The answer is “the amount of energy a human body uses when it is completely at rest”, and why is this important? Well, for most of us, this is where we burn most of our calories each day! Unless you’re doing a couple of hours of hard training, then it's likely that your REE will be responsible for most of the energy you burn for the day. 

REE represents the energy needed for things like breathing, keeping your heart pumping, regulating body temperature, allowing your brain to keep thinking, as well as keeping the other organs in your body going. Interestingly, moving fluids between different cells and tissues of the body is one of the most energy demanding things that happens in our body day to day. When we say “resting” we mean while you are completely at rest, not asleep, but if you were lying down in a quiet room not thinking too much and not talking for 30min type of rest. As well as REE, moving around as part of your normal day, eating, exercise etc., all make up different ways in which we expend energy. 

Not all cells are the same

Because every cell in your body needs a certain amount of energy to stay alive it makes sense that the more cells you have, i.e. the heavier you are, the greater your REE. But different cells in the body require different amounts of energy; muscle cells have a much higher energy requirement at rest than fat cells. So two people may be the same weight but if one has more muscle and less fat then they will have a higher REE. 

Your REE changes

There are several things that can change your REE. We talked about muscle being more energy demanding than fat, so building muscle is one way to increase your REE. If you are fighting an infection and have a temperature, this will cause a temporary increase in your REE, and as we age our REE slowly decreases as we get older. This happens relatively slowly for men, and the same is true for women until menopause, when there is a larger drop in REE. 

hexis uses REE as well as a range of other metrics to provide you with a live view of your energy. REE forms a big part of our body's energy balance throughout the day. This is an important part to consider when making fueling suggestions to optimise your training and lifestyle goals. 

Dr. Sam Impey

Performance Scientist

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Dr. Sam Impey