Stop Falling for These 5 Absurd Myths About Metabolism

As a dietitian that works with clients on recovering from their eating disorders, I’ve found one of the most misunderstood topics is metabolism. There are so many myths around metabolism. This is not surprising considering metabolism a complicated and not fully understood physiological set of functions. Defined, metabolism is how your body manages to use energy from your food. Despite what we still might not fully understand completely about metabolism, let’s demystify some common myths surrounding metabolism.

5 Myths About Metabolism

Myth 1: Metabolism never returns to normal.

When your body is not receiving the energy it needs, either through restriction, purging, or prolonged under-eating, metabolism aka energy needs are reduced greatly. Some symptoms common of eating disorders include: a slowed heart rate, reduced body temperature, blunted hunger, or slowed digestion.

Over time, once your body begins to receive regular nutrition at biologically adequate levels, your metabolism responds proportionally.

Eating adequately has to happen FIRST to stimulate your metabolism to use the energy it’s receiving to build healthy muscle tissue – a driver of metabolism.

Myth 2: Metabolism should be the same as your peers.

When you are recovering, your body is repairing muscle, bone, organs, and deep essential fat tissues. This process uses a lot of energy. More than the average person. Often times, your eating disorder leaves you unsure of how much you should be eating. You might rely on comparing your meal plan or even your own portions to peers around you. Aside from eating disorder recovery this is an inaccurate comparison.

Metabolism is highly individualized from person to person.

Also, we can’t forget that we don’t know what others are eating when we aren’t around!

Myth 3: Metabolism is the same as your Resting Metabolic Rate (RMR).

RMR is the amount of energy your body uses to perform the essential functions of staying alive. In other words, the energy to beat your heart, contract your lungs, regulate blood sugar and body temperature. These are functions that occur even if you never get out of bed for the day.

In addition to RMR, we expend energy through normal daily activities like laundry, drinking water, etc. Even if you are fairly sedentary in your day (studying or sitting) you still use energy above and beyond your basic bodily needs. Something we don’t hear about often is the energy we expend digesting our food. That’s right, you use energy to eat! This process is called the thermic effect of food or TEF.

Also consider physical activity outside of daily life – like yoga, taking a walk with a friend, playing a sport, etc. We often assume metabolism is a net zero process – calories eaten weighted against calories burned in exercise. Instead, a simplified version of the complex process includes: metabolism = RMR + activities of daily life + TEF + physical activity. Most people would be surprised to know that their RMR is 50-65% of their energy needs. For example, a 25-year-old 140-pound female would use approximately 1300 calories just to function her body in a day.

Myth 4: If you eat more than usual, you will gain weight.

It’s common to assume that if we eat more than our bodies “need” at any given moment, the “extra” energy will go right into storage (read: fat). This is not necessarily true. Bodies have lots of storage sites that serve as temporary places to store energy to be used later.

Our liver and muscles store large amounts of carbohydrates so we can utilize them as needed and to keep our blood sugar regulated throughout the day!

The human body strives to maintain homeostasis – which means it has plenty of processes in place to ensure that we maintain our weights.

Myth 5; Green tea and spicy foods increase your metabolism.

There are small amounts of research that show us these foods can speed up metabolism by acting on thermogenesis. This is the thermic effect of food (TEF) discussed above. However, this effect is incredibly minor and likely not the area to target in improving metabolism. If you enjoy the antioxidants in green tea and the taste of spicy foods then wonderful. But if you’re consuming them to increase metabolism turn your efforts to eating adequately and gaining muscle mass!

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  1. says: Lauren

    Might consider taking the numbers out of this post. “For example, a 25-year-old 140-pound female would use approximately 1300 calories just to function her body in a day.” Or try to specify that this is the RMR? Just something to consider

  2. says: Martha Cooper

    Thanks for clearing up the myths! I have suffered from both anorexia and bulimia, so I’ve been entrapped In all sorts of lies, but it’s great to see some truth in it all.
    I think the fact that our bodies need energy even if we remain completely sedentary throughout the day is a huge one for us ED patients to believe. Still working on it :).

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