Calories in vs Calories out – A Simple Guide to Balance

What is a Calorie?

When God created the Earth, calories came into existence, and humans must obey God’s law, which says that all the calories consumed must either be utilized or stored as energy (mostly fat and some carbs)! And they lived happily ever after. The end…

I actually don’t believe in God, so I’ll be happy to elaborate in the name of science. The law in question here is the first law of thermodynamics, which states that energy cannot be created or destroyed; it can only be converted from one form to another. Our friend, the calorie, is just a unit of measuring energy—it is known, defined, and fixed. It is the energy needed to heat up a gram of water by one degree Celsius. In nutrition, the term “calorie” most often refers to (depending on the part of the world) a kilocalorie or a big calorie, which is 1000 calories. So we say “calorie,” but we mean 1000 times more.

Getting back to food… Everyone and their grandma is talking about macronutrients—carbs, protein, and fat (with water and alcohol sometimes sneaking into the conversation). These are chemical compounds that animals consume to derive their energy from. Since energy can be measured in calories, macronutrients provide us with calories per gram. So far, so good… Some macronutrients are more energetically dense than others, with protein and carbohydrates providing 4 and fats providing 9 calories per gram. Additionally, fiber contributes 2, and although alcohol is not essential for our survival, we’ll mention it here with 7 calories per gram. [ 1 ]

Calories in can be calculated by multiplying the weight of the macros we consume in grams by the respective number of calories per gram for each macronutrient.

Calories out involves more components and can be a bit trickier to track. Our total daily energy expenditure is divided into the following, and we’ll delve into each in more detail:

Basal metabolic rate (BMR)
Non-exercise activity thermogenesis (NEAT)
Thermic effect of food (TEF)
Exercise activity (EA)

BMR represents the calories burned just by being alive, such as when lying down, resting in a thermally neutral environment, not even digesting food. Unless we’re engaging in pretty intense exercise, BMR constitutes the largest portion of our daily expenditure.

NEAT includes all the involuntary or routine movements we make, from waving our hands while talking to tapping our foot at the desk, fidgeting, postural effort, or activities like pacing around during a phone call. I wouldn’t classify walks as NEAT. We do a lot of unintentional and essential walking, like pacing and going to the bathroom. However, if you choose to walk to work instead of taking the bus, that is exercise in my book.

TEF is responsible for the “a calorie is not always a calorie” statement. When extracting energy from food, our body expends a certain amount of energy in the digestion process. As a result, the net energy available to us isn’t as high as the original caloric density of food. TEF varies for different macronutrients. For example, protein utilizes a larger proportion of the calories it provides (20-30%) for its digestion, in contrast to carbs (5-10%) and fats (0-3%). [ 2 ] So, while a calorie is still a calorie, not all sources of calories give us the same bang for our buck.

And finally, exercise. Basically, any form of exercise is beneficial. Determine what you want to achieve or what you enjoy, and engage in that activity. If you’re aiming for a greater caloric deficit, increase the frequency. Stay attentive and adaptable—if it causes discomfort, consider progressing more gradually, modifying, or changing the exercise. While this is a topic in itself, the bottom line is that exercise equals good!

Most common mistakes!

When tracking caloric intake, it is easy to over- or underestimate portion size, neglect liquid calories, or ignore cooking oils. Another obstacle to maneuver around is up to a 20% error in food labels’ calorie estimation. [ 3 ] On the other hand we do lose around 2-10% of our energy intake as undigested food through our stool. [ 4 ]

The best advice is to maintain consistency in your approach. Hypothetically, even if your calorie calculations are consistently 10% high, but the daily calorie intake remains constant, you can adjust accordingly if you’re not achieving your weight loss/gain goal.

Calories out presents a few additional challenges. As we follow a diet, our bodies resist by decreasing calorie expenditure through reduced BMR and NEAT. This effect is known as metabolic resistance or thermogenic adaptation. Therefore, as we lose weight, our BMR decreases more than can be predicted solely by calculating it from our body mass. For example, a person who loses 20kg to reach a body weight of 80kg may experience a 3-15% reduction in energy expenditure at rest over 24 hours (lower BMR) compared to someone with a consistent 80kg weight, of the same age, gender, and body composition, who has never dieted. [ 5 , 6 ] A similar phenomenon occurs with NEAT. Involuntary movements become less pronounced—hand waving, pacing around, and even blinking may decrease.

We can try to mitigate a part of our reduced NEAT by counting our steps prior to a caloric deficit and account for a potential reduction by incorporating deliberate walks or other forms of exercise.

Do you have to count calories to lose weight?

Well, no. If your eating habits are consistent and predictable every day, you can consider adjusting your portion size or increasing your calorie expenditure through exercise. Other forms of calorie management can also be helpful, such as time-restricted eating or limiting a specific macronutrient. Choose the approach that feels least restrictive to you because adherence and making it a lifestyle are what make the diet effective in the long run.

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