The Truth About Calories
The health and fitness industry swings back and forth between what a calorie is and what they mean for our health. You have probably heard from a personal trainer or a nutrition influencer that both a calorie-is-a-calorie and a calorie-is-more-than-a-calorie. But the last time I checked, we eat food or whatever restaurants/ our aunts are trying to tell us is food. Most of us do not seek to eat calories, we seek to eat food.
What is a Calorie?
A calorie is a unit of energy measurement. Our European friends measure the energy in Joules. Energy is typically measured in the amount of energy required to heat water.
The human body is 73% water. However, the majority of energy use is not for heat production. For example, your brain weighs about 10lbs and uses about 500 calories per day, or 20% of your total daily energy needs. Therefore a greater portion of energy use is for metabolically active cells and the tissue they form.
How are calories measured?
Calories in food were originally, directly measured via direct calorimetry. This process of calorimetry involves drying food or its components, burning the dried bits, and measuring the heat that was released. To measure this heat, they used pre and post-temperature differences of water.
Today, we are able to use an indirect method. This system uses the average values of 4 Kcal/g for protein, 4 Kcal/g for carbohydrates, 9 Kcal/g for fat, 7 Kcal/g for alcohol, and 0 kcal/g for fiber.
Where if a given food we are eating weighs 100g and it is 50% carbs, 10% fat, 20% protein, and 20% fiber. It will have 200 calories from carbs, 90 calories from fat, 80 calories from protein, and 0 calories from fiber.
Should you measure calories?
I do think that you should measure calories but only if it gives you motivation, and accountability, or provides additional information outside of calories.
But generally, no we should not be measuring calories. The reason we should not be measuring calories is that it does not provide us with accurate information. The issue is that the current system we use is an estimation and the labeling of foods/ food products is mathematically rounded. For instance, a food may contain 1 gram of fat but be labeled as fat-free because it was estimated to have .5g or 4.5 calories of fat which can legally be rounded down to 0 grams of fat.
Inaccurate labeling is fairly common. A research study in 2012, showed that on common snack foods the label underestimated calories by an average of 7.7% but inaccuracies could reach as high as 30%. Imagine eating a premade diet meal and instead of eating 400 calories, you eat 550 calories.
Another inaccuracy with dietary estimates is fiber. Although we cannot digest fiber directly, the bacteria in our gut can. These bacteria change fiber into small fats that we absorb and use for energy. On average, you get about 3 calories per gram of fiber. This ability to break down fiber improves as you regularly eat more plants and decreases as you eat more processed foods.
However, if you avoid snack/premade foods altogether you run into similar issues. No one knows how many calories your specific salad or steak contains. Even the vitamins and minerals in a salad are based on soil conditions and the nutrients in the steak are based on its food’s soil conditions.
I am all in favor of using food logs or diaries to get a general picture of your diet and to help reestablish where you need to take your nutrition and eating habits. I usually do this for 1-2 weeks once or twice a year and recommend this to my clients as well.
Is a Calorie a Calorie?
As you will find with most of my blog posts, I am in the middle.
Yes, I think that on a broad and general scale, a calorie is a calorie when it comes to total energy balance. This means that for you to gain weight or lose weight you need to be below or above your caloric needs. But this idea of energy balance is a lot more complicated than that. To learn more about this balance and how the body maintains energy homeostasis check out .
Yet, a calorie is not just a calorie. The human body is not a combustion engine. We get our calories from food. Food tells a story, food is about culture and self-identity. Food is not just what we eat but what our food eats. When it is all said and done, good nutrition is not about calories it is about what makes us healthy, feel, and perform our best.
1) Jumpertz, R. (2013). Food Label Accuracy of Common Snack Foods. NIH Public Access. Published. https://doi.org/10.1002/oby.20185 . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605747/pdf/nihms-424333.pdf
2) Schwarcz, J. (2018, September 6). How is the caloric value of food determined? Office for Science and Society. https://www.mcgill.ca/oss/article/nutrition/how-caloric-value-food-determined