• Steven Yeh

Why a Calorie is Not a Calorie

Updated: Dec 20, 2021

You may have heard the saying "Calories in, calories out". It doesn't matter whether you eat 100 calories of chocolate or 100 calories of broccoli, both will impact your weight the same way. In fact this is something that I have preached in my article on how to lose weight. Now while 100 calories of anything will impact your weight the same way, there are many other factors that don't make all calories equal. Our bodies are extremely complex machines that process foods in different ways. Different foods and their nutrients have a huge effect on our hormones and hunger level.



Get our list of Top 5 Low Calorie Foods to Help You Lose Weight


There's a lot of information to take in from this post, so we devised a list of our top 5 low calorie foods that you can add to your diet in order to help you lose weight!

Be sure to take a look after you read!



Don't believe me? Here are 3 reasons on why a calorie is not a calorie:



1. Foods Affect Leptin and Ghrelin in Different Ways


Your hunger levels are mostly controlled by two hormones; Leptin and ghrelin. Leptin regulates your energy balance and suppresses food intake, while ghrelin is the hormone that makes you want to eat.


According to You & Your Hormones, if you have high levels of leptin, you may develop leptin resistance. This causes your brain to no longer respond to leptin, which will result in weight gain as your body doesn't know when to stop eating. When you have low levels of leptin, your brain will think you are starving to death. This will also cause you to eat more, resulting in weight gain. When it comes to leptin, you want to have the Goldilocks amount. Not too much and not too little.


If you have higher ghrelin, you will get hungrier, while if you have lower ghrelin, your hunger goes down. According to this article, ghrelin is primarily regulated by the intake of food. It becomes activated when the stomach is empty and inhibited when the stomach is stretched (after a meal). This is an extremely important detail that makes a calorie not a calorie.


Let's take the example I used earlier: 100 calories of chocolate vs 100 calories of broccoli, but instead of 100 calories of chocolate, I'll use 70 calories for visual purposes.


As reference, here's what they would roughly look like visually:

Ghirardelli Chocolate Squares - 70 calories Bowl of Broccoli - 100 calories



Visually, it's no surprise that there is much more food in 100 calories of broccoli compared to 70 calories of chocolate. Although on paper, they both give the same amount of energy, the broccoli is much more satiating than the piece of chocolate. This is because of the sheer volume of the broccoli taking up much more room in your stomach. Remember, ghrelin is activated when the stomach is empty and inhibited when the stomach is full. Your stomach doesn't actually care about how much calories are in your food, but how much food you ate.


It doesn't stop there. Foods also have different effects on leptin and ghrelin depending on its nutrients. Foods with high fats or carbohydrates decrease ghrelin, therefor reducing hunger levels. A combination of the two increases leptin levels, which will make you feel more satiated. Foods with high fiber also reduce ghrelin by taking up more space in your stomach, as your body takes longer to digest fiber.

2. Foods Have Different Thermic Effects



Another reason why a calorie isn't a calorie is because of the thermic effect of food (TEF). The thermic effect of food is the amount of energy your body burns through in order to digest and process each macronutrient. The amount your body burns is dependent on several factors, including age, meal timing, and the amount of macronutrients (fat, carbs, and protein) in the food.

Here is a general estimate of the TEF of each macronutrient:

  • Fats have 9 calories per gram and a TEF of 0-3%

  • Carbohydrates have 4 calories per gram and a TEF of 5-10%

  • Proteins have 4 calories per gram and a TEF of 20-30%


We can see that proteins have the highest TEF out of all the other macronutrients and have 4 calories per gram. This means that if you had 100 calories of protein, you would have burned 20-30% of the 100 calories through digestion. So although you had 100 calories, once your body has digested it, you really had 70 - 80 calories.



3. Foods Have Different Satiation



Satiation is an important part in feeling full and it's no surprise that different foods will make you feel more filled than others. Like the example used earlier, it is much easier to eat 100 calories worth of chocolate than it is to eat 100 calories worth of broccoli.


Knowing how satiating the food you're eating is an incredibly important part in helping you reach your daily caloric goal. There are many factors that determine how satiating a food is, but a good guide to use is the satiety index. The satiety index is a list of foods that have been given a percentage on how satiating they are compared to white bread.


From the list we can see that whole foods like potatoes, oatmeal, apples, and oranges are the most satiating, while junk foods like cake, doughnuts, and candy bars are the least satiating.


If you eat foods that are at the bottom of the satiety index, you will become hungrier faster and end up eating more calories. If you eat foods at the top of the satiety index, you will feel full for longer, which will reduce the calories you will want to consume. As a general rule of thumb, we can conclude from the satiety index that whole foods are generally more satiating and will keep you full for longer, while heavily processed foods won't fill you up as much.



To Sum It All Up


Despite the fact that all calories carry the same amount of energy, not all calories are the same. Different foods and their nutrients have different effects on your hormones, energy expenditure, and satiation. Eating low calorie, high volume foods along with foods that are rich in protein is the key to staying satiated. Whole foods like green vegetables and lean meat will likely fit this description. While at the end of the day, it is "calories in, calories out" to lose weight, the foods you choose to eat can make that journey much more easier.


Get our list of Top 5 Low Calorie Foods to Help You Lose Weight


There's a lot of information to take in from this post, so we devised a list of our top 5 low calorie foods that you can add to your diet in order to help you lose weight!

Be sure to take a look after you read!



Did you learn anything new from this article? Let us know in the comments below!


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