CICO Diet and Tracking Macros: an ideal partnership for weight loss?

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Estimated reading time: 4 min

Weight loss feels like a very complicated idea for most of us. Myself included. However, the core idea of weight loss can be boiled down into a singular, relatively simple idea: Energy Balance (or CICO).

Simply put, your body loses weight when more energy leaves it than enters it. 

What is CICO?

What the heck does that mean and how does energy have anything to do with weight?

That is a great question right there. To answer this question we need to recall our good friend Albert. You know, the guy with the crazy hair who taught us about gravity. 

Well, it turns out that energy and mass (which is what your body is) are essentially the same thing. All the mass in your body is actually energy (weird right?), which means that we can think about weight loss as a change in energy balance. 

The fundamentals of physics and the laws of thermodynamics suggest that energy balance should be the mechanism by which humans either gain weight or lose weight. Several decades of scientific inquiry have been conducted and the totality of the evidence supports the idea that energy balance is the primary mechanism by which humans do in fact either gain or lose weight.

This idea has been encapsulated in a model of weight loss and weight gain known as calories in calories out, also known as CICO.

Calories in Calories out: The Math Behind Weight Loss

Now, we need to do two things there real quick. These two things are both REALLY simple… and REALLY complicated. 

So here we go. 

Simple things first. 

If we turn our bodies into a math equation that can make sense to us, it would look something like this:

Calorie Intake – Calorie Output = Change in Body Weight 

Now, we can use an example to explain how this works in the real world. Let us imagine over the course of 180 days you have an average daily calorie intake of 2500 calories and an average daily energy expenditure of 2300 calories. We would see something like this: 

(2500 – 2300) x 180 days = 36,000 

This means that over the course of 180 days, we have accumulated around 36,000 calories as surplus in our body. Now this roughly translates to around 10 pounds of body weight*. Now if we reverse that math and consume 2300 calories and expend 2500 calories per day for 180 days, we end up with the following:

(2300 – 2500) x 180 days = -36,000 

This means that over the course of 180 days, we have accumulated an energy deficit of 36,000 calories, which will leave our body in the form of body mass. 

Now the complicated part

Humans are not robots and our bodies don’t just do metabolic math and balance everything out like we had to do in highschool math or freshman year of college chemistry (Stoichiometry still gives me the heebie jeebies).

It turns out our behavior is REALLY complicated.

There are a lot of things that affect both our calorie intake and our calorie expenditure. 

For example, here is a list of just a few things that can affect how many calories we eat a day without any conscious decision making:

  • The tastiness of the food we eat  
  • The energy density of the food we eat
  • What time of day we eat
  • Whether we eat out of a bag or off a plate
  • If we are stressed or anxious

On the other side of the equation, how many calories we expend in a day can vary a lot based on our jobs, habits, living environment etc. It is really hard to control all the details without really focusing on it. 

Ok, so now we know what drives weight loss… so how the heck do “macros” fit into this?

Why Tracking Macros Works Alongside CICO

Alright. Let’s get right into it.

The reason macro tracking works for weight loss is that macro tracking provides a detailed way of tracking calories and also helps to ensure that the calories you are getting are meeting your body’s basic nutritional needs. 

Let me break that down in a little more detail for you here. 

Imagine you know that you need to eat roughly 1750 calories for roughly 180 days to lose 20 pounds. The next question(s) that you might ask yourself are:

  • How do I know what to eat?
  • How do I know how many calories are in my food?
  • How do I make sure I eat the right calories for my body?

This is essentially what tracking macros helps you do. 

Tracking your macros is essentially taking those 1750 calories and breaking it down into the nutrients your body needs and the calories associated with it. 

Let us just imagine you are a 45 year old, 5’6” female who weighs 180 pounds and wants to lose 20 pounds and your target calories are 1750. A macro calculator might help you break down that 1750 calories as follows:

  • 140 grams of protein (~0.77 grams per pound of body weight). This equals 560 calories because protein contains 4 calories per gram
  • 160 grams of carbohydrates. This equals 640 calories because carbohydrates contains 4 calories per gram 
  • 61 grams of fat to round out the calories. This equals ~550 calories because fats contain 9 calories per gram.

This approach provides a few really helpful tools for people to lose weight. These tools include:

  • Developing an understanding of the total calorie needs a person needs in a day.
  • Creating knowledge and skills around the nutrients and total calories in the foods they consume.
  • Provides flexibility around exact food choices (meaning they can chose a variety of foods that can meet their needs).
  • Encourages autonomy, problem solving, and long-term skill development. 

What If I’m Already Following Another Diet?

Is CICO and tracking macros the only way to lose weight? Absolutely not. 

However, essentially all other ways of losing weight either come down to the same principles of macro tracking (e.g. eating in a deficit) AND you can utilize the skill of counting your macros when following any other diet. 

Put another way, if someone decides to lose weight via Weight Watchers, Keto,  Intermittent Fasting, or another approach they can also choose to count their macros while they are following that approach. This would increase their likelihood of success on those approaches because the person would be able to ensure they are eating in a deficit following those eating paradigms. 


You can lose weight in a lot of ways, but to develop the skills, tools, knowledge to be able to sustain that, or lose weight again in the future on your own, understanding the function of CICO alongside macro tracking is one of the best tools you can put in your toolbox. 

*The exact math behind weight loss and weight gain is a bit more complex than a 3500 calorie deficit leads to 1 pound of body weight loss, but it is accurate enough to provide a rough example of how to think about calorie

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