The concept of calorie counting has been around for decades, but does it truly matter for your health? Understand the facts, and why precision is a myth.


One of the biggest myths in eating is the idea of “calories in, calories out.” 

There’s an idea floating around that by simply “balancing” or manipulating the number of calories we take in with the number of calories we burn, there’s a direct path to weight change, health, and happiness.

In reality, there are many reasons that calorie counting is unnecessary, is scientifically unsound, and likely damaging to our relationship with food.

But first, what actually is a calorie?

Since calories are painted as an entirely negative concept, it can be easy to forget what they actually are and how they serve us. 

A calorie is simply a unit of energy – the amount of energy that is required to heat 1 kilogram of water by 1˚C. Calories and energy can be used interchangeably – in fact, using the term “energy” may help you remove some of the stigma that comes with the word “calorie”.

You may also be under the impression that an equation used to estimate your ’basal metabolic rate and a nutrition facts label can ensure total confidence in your calorie knowledge. But think again – this system has a lot of holes in its logic. Here’s why.

1. Food labels are not perfect.

The Food and Drug Administration, which regulates nutrition facts labels, nutrition claims, and accuracy of labeling, sets certain standards for the information on the nutrition label. 

Theoretically, this is to reassure customers that they are, in fact, eating what they are told they’re eating. In the case of situations such as food allergies, labeling is not only important but lifesaving. 

However, for certain nutrients and total calories, the FDA allows a margin of 20% accuracy. This means that if a facility is to be audited or inspected by the FDA, the FDA will conduct its own nutrient analysis on food and compare it to the company’s nutrition label. The ratio of the measurement to the label has to be within 120% or less of the value.

2. We all metabolize food differently.

There are many factors that play into how we absorb energy from food. A helpful way to frame food and drinks that provide energy (calories) is to recognize them as sources of “potential energy” – not necessarily the exact amount of energy we extract. Here are a few things that affect how we absorb nutrients and utilize energy from food:


The bacteria lining our gut need energy too! Simply put, they’re conveniently located in a place where it can impact some of the food energy before we absorb it for ourselves. Two people can eat the same food, and end up utilizing different amounts of energy.


Broadly speaking, our individual genetic makeup affects how we store and use energy – this is different for each person and different as time passes, since food, movement, and other lifestyle factors can affect gene expression.


Insulin resistance (from type 2 diabetes or PCOS), medications, thyroid conditions, pregnancy, disability, and more can all affect how we utilize food (and how we experience hunger and fullness cues). 


A study of Thai and Swedish subjects showed that iron absorption was decreased after a blended meal vs. a meal of regular texture, which may be due to a decrease in enjoyment and palatability.

3. We need calories to live.

Metabolism and how the body uses calories is what helps sustain life. The number of functions the body carries out every minute is long – breathing, blinking, thinking, moving, cell growth and repair, circulation, maintaining a heartbeat, digesting, producing blood cells. 

It takes a lot of power to power a body! Intentionally reducing calories sets your body up to prioritize which critical functions to maintain while allowing others to fall by the wayside. For example, it can impact having a regular menstrual cycle, optimal innervation and blood flow to the gut (leading to slower digestion), or having trouble concentrating and thinking clearly.

4. Your body is not a bank account or calculator.

Your body can’t be reduced to a simple equation or balance sheet. The idea that we can adjust or control our energy stores by eating more or less than our calculated needs is an extreme oversimplification of the body’s functions.

Calories in, calories out makes assumptions about how the body works, including:

  • The body will passively accept not having its needs met.
  • More calories = automatic weight gain and less calories = automatic weight loss.
  • We have control over our weight.
  • The body has the same exact needs every single day.

In reality, it’s more nuanced than this simple concept can ever capture. Simply put, the body wasn’t meant to starve. When we’re not getting enough food, our bodies respond at several levels, including hormonally, to try to protect us from perceived starvation.

Our bodies don’t care about the reason you’re undereating, they just know they’re not getting enough. Diets aren’t meant to work, and it’s unproductive and harmful to try to force our bodies to exist outside of their natural weight.

5. Calorie counting is not without harm.

Calorie counting isn’t a neutral behavior, nor one without side effects. Calorie counting apps and tools can predict and reinforce eating disorder behaviors.  Use of nutrition factors labels may also predict binge eating and engagement in disordered eating behaviors.

Having a hyperfocus on food, or a dichotomous (all-or-nothing, black-and-white) mentality, and using exercise to compensate for eating is not part of a healthy relationship with food. Trying to “save calories” for later or making up for eating will likely result in extreme hunger and binge eating, perpetuating the diet-binge cycle. In addition, the amount of calories recommended by most calorie calculators is far, far below what most adults need just to survive. It’s even below the amount used in the Minnesota starvation study). 

6. Nuance matters. 

Talking about the harms of calorie counting or restriction does not mean that there is never a time or a place to talk about them, or that calories don’t exist. In a clinical setting, predictive calorie equations are helpful in calculating tube feeding to start a feed and adapt based on the patient’s needs as time progresses.

Rough estimates are also helpful for those in eating disorder recovery to ensure they are eating adequately and restoring weight if that is part of their care plan. However, that time and place are rare, and typically not for the general population.

After all, your body is not a machine.

Adapted from the original post.

Amy Hanneke, RDN, LD is a Registered Dietitian and owner of Satisfy Nutrition.  Through an anti-diet approach in her nutrition coaching practice, Amy firmly believes in helping individuals live a life without restrictions, full of joy, self care, and delicious food. Learn more about Amy at Satisfy Nutrition.