If you’ve been unlucky enough to have stumbled upon pretty much any of the recent internet articles on CICO (Calories In, Calories Out), then you may have read that:
- CICO is a recent diet fad
- CICO is a weight loss diet that’s disastrous for your health
- CICO is about eating cake and pop-tarts
- CICO is about counting calories
- CICO doesn’t work for weight loss because “not all calories are created equal” or because “a calorie is not a calorie”
- * insert any other silliness you may have read here
On the other hand, if you are already well-versed in human physiology, metabolism and nutrition, then you probably just had a good laugh or, maybe, even got a little bit annoyed at all the nonsense that the internet is throwing at the face of the general public.
Well, after we had our good laugh, we thought that it would be best to help clear up some of the confusion around the topic of CICO.
So, in this article, we’ll talk about:
- why CICO isn’t a “diet” or a “recent fad”,
- what CICO really is,
- why a calorie is a calorie (sort of),
- why a calorie isn’t a calorie (sort of),
- whether you need to count calories with CICO, and
- what you should really be doing for fat loss.
What CICO is (and what it’s not)
Firstly, here’s what CICO (which stands for Calories In, Calories Out) is definitely not: a diet or a dietary approach.
Instead, CICO is meant to represent the idea that the energy that goes into the body minus the energy that comes out of the body, equals the change in the body’s energy stores.
This is, of course, merely a rehash of the First Law of Thermodynamics, which states that when energy passes, as work, as heat, or with matter, into or out from a system, the system’s internal energy changes in accord with the law of conservation of energy.
An important thing to note from the above description is the word “law”. Not “theory” or “hypothesis” or “belief”, but LAW.
Following from the above, it’s relatively straightforward to understand why CICO isn’t really a recent thing. Since the laws of physics always have and always will apply, then CICO is also a timeless idea. Consequently, like with gravity, you also can’t really choose if you want to follow CICO or not. You are bound by the laws of physics as is everyone else.
Take home point: CICO is not really a diet, but, instead, a simple restatement of the energy balance equation and, as such, is also timeless and mandatory.
So CICO is just about calories then, right?
Well, sort of but not really.
Again CICO is not a diet and, consequently, doesn’t really make any recommendations with regards to food selection or quality. Instead, it merely explains what happens to the energy stores of a system as a result of imbalances between the net intakes and net outputs that are taking place.
So although you don’t get to choose whether CICO applies to you or not (it does), you can certainly choose how you’ll go about your diet in terms of food selection and timing in order to achieve your goals.
What this means is that you have a choice of using:
- a ketogenic diet,
- a high carb/low fat diet,
- a moderate carb/moderate fat diet,
- calorie counting,
- macronutrient counting, a.k.a IIFYM (If It Fits Your Macros),
- intermittent fasting,
- alternate day fasting,
- a paleo diet,
or any other dieting approach you prefer in order to lose fat (or even gain fat).
Remember, however, that whatever dieting approach you choose, you’re still doing CICO because CICO always applies to everyone at all times.
As you can see in the infographic above, all diets can work for fat loss, provided that they help the dieter achieve a negative caloric balance between intake and output (i.e. a caloric deficit). This, of course, doesn’t mean that the food choices you make don’t matter for health and body composition, since calories from different foods will have different effects on your body.
Take home point: Since CICO is merely meant to explain what happens to the energy stores of a system, it isn’t a diet and it doesn’t give food selection recommendations. This doesn’t mean that it’s just about calories, as food quality matters for health, performance and body composition.
Aha! So a calorie isn’t a calorie!
Well, yes and no.
Remember, a calorie is a measurement unit of heat or energy. Since, in its simplest definition, a food calorie (1 kcal) is the amount of energy needed to raise 1 kg of water from 15 to 16 °C, then, from a thermodynamic point of view, a calorie is, of course, a calorie.
However, things get a little more complicated when it comes to the human body, as:
- the energy released from the combustion of food in a calorimeter is not always identical to the energy available to the body from eating that food,
- different foods with the same caloric content can have varying amounts of metabolizable (or usable) energy,
- different foods can differentially affect energy intake, and
- different foods can differentially affect energy expenditure.
However, the implication from the above isn’t that a calorie isn’t a calorie, but that the source of the calories can affect their metabolizable energy, as well as the the two sides of the energy balance equation.
Of course, since CICO is about energy balance, it takes all the above into account.
Let’s reiterate to make this point crystal clear:
– We KNOW that the body is not a “perfect engine” and that the energy liberated from the combustion of food is not always exactly identical to the energy available to the body from the consumption of that food and we KNOW that foods with identical energy contents provide varying amounts of actual metabolizable energy to the body. These “errors”, however, don’t mean that the laws of thermodynamics are “broken” and that CICO doesn’t apply. Instead, they suggest that we have a limited ability to determine exactly how much metabolizable energy a given diet contains.
– We KNOW that the thermic effect of different foods and macronutrients varies. As we’ve talked about before, the thermic effect of protein is around 20-30%, that of carbohydrates is around 5% and the thermic effect of fats is usually close to 0%. Again, all of these are part of CICO.
– We KNOW that that different foods can have differential effects on hunger and satiety and, consequently, affect energy intake. We’ve also discussed this in another article. Foods that are rich in protein and/or fiber and/or water tend to be more satiating. There is also research which suggests that ketogenic diets may have independent effects on satiety. As you will have guessed, these are taken into account by CICO.
Take home point: From a thermodynamic point of view, a calorie is a calorie. However, calories from different food sources can provide different amounts of metabolizable energy to the body and can have different effects on our energy intake and output. This doesn’t mean that the laws of thermodynamics are broken and that CICO doesn’t work, since CICO takes all the above into account.
But CICO is still about counting calories, right?
Whether you prefer to count calories or not is entirely up to you. Again, CICO merely explains how the energy balance equation works. It doesn’t make recommendations regarding how to go about your diet, including whether you should track energy intake or not.
However, not counting calories, doesn’t mean that CICO won’t apply to you. Think of it like closing your eyes. The fact that you can’t see the world around you doesn’t mean that it’s not there anymore and that all your problems are gone. Similarly, keeping your eyes open doesn’t mean that you will necessarily make great decisions in life.
Should you count calories?
Well, we can’t give you an answer to this question that definitely applies to you, but we can help you figure it out on your own with a little Facebook post that we made some time ago about this very topic. Check it out, below:
Take home point: CICO doesn’t make recommendations regarding how to go about your diet, including whether you should track calories or not – that’s entirely up to you. However, not counting calories doesn’t mean calories don’t count.
What to take away from this article
With the above said, here are the main points that we want you to take away from this article:
- CICO is not a diet, let alone a recent diet “fad”. It’s simply a restatement of the energy balance equation. It always has and always will apply to everyone.
- CICO is not about counting calories. You can lose or gain fat without ever counting a single calorie. Calories count but you don’t have to count them.
- CICO is neither “healthy” nor “unhealthy” because it’s not a diet and because it simply doesn’t make any specific dietary recommendations. Whether you make healthy dietary choices or not is up to you.
- A calorie is a calorie from a thermodynamic point of view.
- The quality of the foods where the calories are coming from matters for body composition, health, energy levels, etc. This doesn’t go against CICO and the laws of thermodynamics, nor does it mean that a calorie is not a calorie.
- All diets work for fat loss, provided that they allow you to eat fewer calories than you expend consistently over time.
What we recommend for fat loss
Also, as we’ve mentioned before, if you want to lose weight and fat, we recommend that you find a dietary approach which:
- helps you create a large enough caloric deficit for a sensible rate of fat loss,
- is comprised primarily of a variety of minimally-processed, micronutrient dense foods,
- provides enough protein to prevent losses in lean body mass and to help with satiety,
- honors your individual preferences with regards to meal timing, food choice, and so on,
- can be adhered to in the long term, and
- promotes a healthy relationship with food.
If you are a fellow evidence-based fitness professional and are also annoyed about all the nonsense articles on the internet regarding CICO, please share this post. The more people we reach, the better.
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Also, if you want to learn more about fat and weight loss, we highly recommend that you check out the following posts:
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