A calorie is a calorie is a calorie? The truth behind “calories in, calories out.”



If I were to ask you, what do you think the best diet is to successful weight management and a healthy lifestyle? I guarantee 90% of you would say, “Eat real, wholesome food and avoid processed “fake” foods.” Absolutely. But do you know why?

Second question, how does one lose weight? Calories (AKA energy) in, calories out, right? The clear cut answer is yes, but how do we measure that accurately?

The answer to these two questions are simple, but the why is so much more important. With a little science to explain it, I am hoping the “why” will help you understand the bigger picture of energy (calorie) input and output.

Let’s identify how a calorie is actually measured and how it effects our body.

The calories we see on nutrition labels are determined in a science lab by incinerating food. So when a nutrition label reads “100 calories,” that information was gained from scientists burning that food sample with a measurement tool called a bomb calorimeter. Problem is, our bodies don’t incinerate food, it digests food.

“Your body is smarter than you. It’s a dynamic, adaptive, living organism. Not a machine.” (Krista Scott-Dixon)

Your body’s way of metabolizing food (the amount of calories needed for digestion) can either speed up or slow down depending on a number of factors. These factors include our hormones, timing of eating (such as eating after a vigorous workout at the gym) and nutrient density. For example, eating a nutrient dense meal high in protein is harder to breakdown so your body will rev up to accommodate the demand of digesting the meal. On the other end, if you feed your body with low nutrient dense foods (AKA fake foods) your metabolism can slow down because the deprivation of key nutrients causes a metabolic response to conserve energy. Yes, the “starvation mode” that you’ve all heard about is true. Deprive your body of essential nutrients and it will deprive you from proper metabolic functions. So in order to have good digestion and metabolic response, we need to fuel our bodies with nutrient dense foods (AKA real food).

Here is a direct excerpt from the Precision Nutrition course I am currently taking that explains digestion impressively:

Digestion is an active process with innumerable moving parts (including trillions of bacteria that do much of the “digesting” part for us). It’s not just moving “calories” along a conveyor belt. The way we digest food can change the amount of energy we can get from it by up to 25%. The more easily we can break down a given food, the higher the available energy, and vice versa. That means our digestion can be affected by:

  • Macronutrients and fiber: Protein, fiber and resistant starch don’t provide the same amount of energy to our body as when burned in a calorimeter.

  • Processing: If a machine has chewed and manipulated the food for us, our mouth and gut don’t have to work much. White flour (processed) in a muffin is handled differently than fresh (wholesome) berries. Processed food takes less energy to digest and absorb compared to whole foods.

  • Cooking and heat processing:This often breaks down the stuff (such as fiber) that our digestive system might get hung up on, allowing us to get more energy out of a given food. One researcher thinks that cooked food may provide 25-50% more calories than raw food.  

  • Our GI tract health and flora: Our intestinal bacteria do much of the work of “digestion” for us. When our internal bacterial environment (aka our microbiome) changes, our ability to absorb nutrients changes.


So yes, we can assume energy in and energy out, but there’s a person in between with functions other than a simple measurement tool. There is no precise method to figuring out how many calories we are truly consuming and the energy we are expending from eating those foods. What we do know is that providing our body with nutrient dense foods expend more calories in the digestion process, which is exactly what we want. Not only that, but the converted energy is used to energize us throughout the day and improve our athletic performance, which essentially means more calorie expenditure! Can you say DOUBLE WHAMMY!!?


Putting this information to use in terms of making food choices is most important. Eating a 100 calorie chips ahoy pack will provide you with no beneficial nutrients to be broken down. In fact, your body may have no idea what to do with the food because it doesn’t recognize half the ingredients, so it will cause all sorts of internal disruptions. So if you’re lucky, your body will digest what it can. Whereas if you eat 180 calories of almonds (about ¼ cup) your body will get to work with the nutrients provided, adding additional energy expenditure through the process of digestion.


Now I may be sounding bias and a hater of all companies that promote low calorie, fake foods, but I am just speaking the truth based on the facts. The best thing we can do is try to educate ourselves on this subject and have a simple understanding of what goes on in the body. I get it that most do not care about the science and really just want to know what they should and should not eat. But, to tell you the truth, knowing the basics of why you should eat what you eat, will give you a reason to adapt a healthier lifestyle rather than, well… Just because.

Key information to take away:

  1. Although nutrition labels help you be mindful of the product, nutrition labeling isn’t a perfect system. Calorie counts may be inaccurate or misleading. Don’t rely on your MyFitnessPals for your information either, most of that data is self-input.


  1. Calories are just a measurement of heat. They don’t actually imitate what happens in our body. Remember, we don’t incinerate food; we digest it.


  1. Supplementing low calorie “diet foods” for whole foods won’t help you lose weight. Your body will burn more calories digesting the whole food, even if it’s has more calories.


  1. If you want to be fit, lean and healthy, stray away from calorie counting. Eat to fuel your body and your body will reward you with good health and body composition.


  1. Focus on nutrient qualityof the foods you eat. Eating more quantity of low calorie, low nutrient dense foods will not get you to your goal.


  1. Don’t worry or rely on the numbers so much. They won’t help you as much as you expect. So throw away those point systems and just eat real food why don’t ya!!


Knowledge is power. It’s time to take your power back.


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