Not All Calories Are The Same

When I was taking grade 11 physics we were doing a unit on energy and one of the types of energy that we studied was calories. Calories are important because they indicate how much energy is in food. If we are getting technical, one calorie is defined as the amount of energy it takes to raise the temperature of 1kg of water by 1 °C. Okay… but no one really cares about that. What we really care about is that one pound is the equivalent of 3500 calories. So when you read the number of calories that are in your food, it is telling you how much energy is in the food. This means, that in theory, all calories are equal and 100 calories of chocolate are the same as 100 calories of broccoli.

Alright, so if I burn an extra 3500 calories a week more than I consume, I’ll lose a pound?

The short answer: In theory, yes. That being said, not all calories are equal. Yes, according to the laws of thermodynamics, they are all equal. However, for anyone who has taken some biology we know that foods with a high glycemic index cause insulin to spike. This spike of insulin prevents the release of triglycerides, which are a source of energy when we haven’t recently eaten. Normally, when there are triglycerides in the blood stream, the blood circulates to the brain and lets the receptors know that there is still enough energy for the body to sustain itself. In cases where an insulin spike prevents the release of triglycerides, our brains don’t realize that we don’t have enough energy to fuel our bodies so our brains tell us that we are hungry. What our brains don’t know is that there is still a lot of energy on hand, but since it isn’t getting used, it is stored in fat cells.

This means that the 100 calories of chocolate is not the same as the 100 calories of broccoli. While chocolate causes a spike in insulin, broccoli does not. Refined sugars and processed foods are some of the foods with the highest glycemic index. Essentially, foods that don’t have a lot of fibre will cause this drastic spike in blood sugar levels because fibre slows the digestion process of the food. This is part of the reason why the broccoli or fruit won’t spike your blood sugar the same way that a chocolate bar or a pop/soda will. To get a better idea of what’s high and what’s low check out these links:

Okay, so avoid foods with a high GI?

That’s a good start! But, there’s more to it than that! What we haven’t considered is the energy cost to metabolize the different macronutrients. Different foods are metabolized differently. For example, processed foods tend to be high in simple carbs and fats and don’t require as much energy to metabolize. Whole foods on the other hand tend to be higher in complex carbs and/or protein and require more energy to be metabolized.

“Right, but I can still eat processed foods and lose weight”

Yes, it’s true that people go on the “McDonald’s Diet” and still lose weight. However, there is another component to food that processed foods are also lacking: satiety. The satiety index indicates a food’s ability to reduce hunger and increase the feeling of fullness. The higher the satiety index, the more full you feel. Again, foods high in fibre and protein help increase satiety. For example, a study examined subjects who had oatmeal for breakfast vs those who had frosted flakes. The energy breakdown for the two breakfasts was:

Frosted Flakes Oatmeal
Carbohydrates 66.3g 60.6
           as sugar 35.3g 8.9g
Fibre 0g 8g
Protein 7.3g 14.3g
Fat 5.7g 6.6g
Calories 352Cal 351Cal


The subjects who had Frosted Flakes for breakfast did feel as full for as long and ate more for lunch than those who had oatmeal for breakfast. In addition, as a control for the study, a control group of participants only had water for breakfast and it was reported that the groups who had Frosted Flakes and those who had water for breakfast ended up eating the same amount for lunch.

People often struggle with dieting because of satiety and this study helps to show why. When we don’t feel satisfied from our food we get hungry more often and end up consuming more. While the two meals are calorically equivalent, they are not equal. The Frosted Flakes are higher in sugar and lower in both protein and fibre. Foods that help with the feeling of satiety are those such as eggs, legumes, fruits, vegetables, and whole grains. In other words: the components of a healthy diet.

There is more to a calorie than the calorie itself!

While the short answer to the earlier posed question may be “yes, a calorie is a calorie” there is more to it. When making decisions about food it are important things to consider such as the macronutrient (fat, carbs, and protein) content of the food. Even if two meals are calorically identical, it does not mean that they will have the same effect on your body. If you are considering a diet or looking to achieve a specific goal look beyond what you need in terms of calories. While calories are important, it is more important to be aware of the nutrition facts and ingredients list of your food. Eating properly often requires some detective work to determine whether there are added sugars. The easiest way to eat healthy is to stick with whole foods. While having to do all of your food prep can turn out to be time intensive, it’s the best way to make sure you are eating right!


If you think any of the information I provided seems a bit sketchy, here are my sources!

2 thoughts on “Not All Calories Are The Same

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