Metabolic Mayhem

What I wish the world understood about bodies

Hello, hello!

March happens to be one of those months where we get an extra Monday, which means we get an ~extra~ special paid post. I’ll be honest, this one was hard to put behind the paywall because I think it is genuinely helpful for everyone to understand. This is my hint, hint nudge, nudge to maybe use your free trial week if you feel like your understanding of metabolism is a bit out of date or has been heavily influenced by diet culture.

And (yet another) reminder that Getting Full starts in April, and that is when I will increase the cost of paid subscriptions. If you would like to lock in the current $4/month price, now is the time to do it! I’m excited for this next step for The Full Life and truly can’t wait to get back into group support. I have found that so many people need to feel and be supported by others to confidently shift their relationship with food and their body. I may be biased, but I think this is something that almost anyone could benefit from.

Without further ado, here are the basics of human metabolism:

Resting Metabolic Rate or Basal Metabolic Rate

Each of us has a unique Resting or Basal Metabolic Rate (RMR/BMR). For the purposes of today, we are going to call them the same thing, but technically, there are very slight differences in what they are referring to based on the amount of activity that is considered “at rest”. The RMR is the calculation of the amount of energy a body uses when not doing anything else. It includes the energy required to keep your heart beating, lungs breathing, brain functioning, blood pumping, GI system digesting and absorbing, and all your other vital organs alive and functioning.

The calculation to estimate your RMR includes data like your height, weight, and gender assigned at birth¹. It is an imperfect calculation that might not be perfectly accurate for every person but is most likely the way that your RD is calculating your needs if you need to be tube fed in the hospital, need a meal plan during eating disorder recovery, or are just looking to learn more about your energy needs. The gold standard for assessing energy needs is an indirect calorimeter, which measures the oxygen/carbon dioxide in your breath to calculate your energy consumption. Most hospitals and practitioners don’t have access to an indirect calorimeter - they are almost exclusively used in research, which is how we end up using these imperfect equations most of the time.

The RMR is an important tool to understand because it is your baseline needs just to keep existing as a human. It makes up at least 2/3 of your full energy needs; meaning that if you don’t even get out of bed in the morning, or open your eyes, or lean over to turn off your alarm you are still using about 2/3 of the energy you would need on a day when you operate as a human who does things. If we aren’t meeting our energy needs at this minimum level, our body has to figure out a way to keep existing without adequate energy intake. Which leads us to…