Myth: A calorie is a calorie, meaning that what we see on the nutrition label calorie-wise will translate directly to what we store in our bodies.

Calories on a label almost never equal calories stored exactly. This is part due to the labeling process, and part due to the different effects different macronutrients have on our bodies.

Below we will explain why the calories on the label don’t exactly equal calories stored, how our bodies process different nutrients and how this effects us chemically, the thermal effect of food, how a calorie can be “just a calorie” as well as so much more, and why it’s still a matter of “calories in versus calories out” despite this.

Is a Calorie a Calorie?

A calorie is a calorie, but only as a measure of energy.

A calorie describes the energy in food and the energy stored by the body after food is consumed. Or more specifically, calories describe both energy obtained from macronutrients (carbs, fats, proteins) and the energy stored by our bodies from consuming macronutrients.

Saying “a calorie is a calorie” sort of implies that 1 calorie on the label translates to 1 calorie of usable energy, but that isn’t completely true.

Different types of macronutrients can have a wide range of physiological effects regarding hunger, hormones, energy gained, energy spent, psychology, physical appearance, and more.

For instance, simple sugars (simple carbs) are simple for our bodies to turn into glucose and consuming them quickly can spike blood sugar, which in turn causes insulin levels to rise, which in turn increases appetite and tells our bodies to store fat. Meanwhile, red meat (a protein) digests slowly and takes extra energy to turn into usable energy, and is thus unlikely to spike insulin levels.

Thus, 100 calories of steak will result in say 75 calories stored over a few hours, while 100 calories of table sugar could result in nearly 100 calories ready for immediate use (plus a sugar crash). And while food labels generally account for this, as we will cover next, they aren’t always perfectly accurate.

Given the above, and the fact that different foods have different nutrients (vitamins and minerals) which also have a wide range of biological effects, we can say each food we eat is wildly different in terms of how our body reacts (and thus “a calorie is only just a calorie” in terms of being a measure of energy)

 

 

How Accurate Are Calorie Counts on Labels?

It used to be that calorie counts were way off, as they didn’t take into account the thermal effect of food. Today, they are a lot closer, but still they are rarely perfect, because as the method for determine calories has gotten better, estimates on labels are still imperfect.[1]

How Are Calories Counted

  • The old system, Bomb Calorimetry: The old system was called the bomb calorimetry. Essentially they burned food in water than counted how many degrees the water rose. This gave roughly: Carbohydrate: 4.2 kcals, Fat: 9.4 kcals, and Protein: 5.7 kcals.
  • The new system, the 4-9-4 or Atwater Method: What you see on a food label today: 4 kcals for carbs, 4 kcals for protein, and 9 kcals for fat, are indirect calorie estimations made using the Atwater system (a conversion system named after its creator, Dr. Wilbur Olin Atwater). The Atwater system is much closer, but food labels are still imperfect.

TIP: Each food has a different amount of net calories and each body is different, so these are just general statements.

 

Food component (source) Energy density
kJ/g kcal/g (4-9-4 Atwater Method)
Fat 37 9
Ethanol (drinking alcohol in Beer, Wine, etc) 29 7
Proteins 17 4
Carbohydrates 17 4
Organic acids (in preservatives, supplements, and animal feed) 13 3
Polyols (sugar alcohols, sweeteners; essentially “fake” sugars) 10 2.4
Fiber (soluble fiber is 2 kcal, insoluble is 0; both are 8 KJ) 8 2

 

TIP: All the other nutrients in food are noncaloric and are thus not counted, despite this one shouldn’t ignore micronutrients or the acids in their diet.

Are Calorie Counts on Labels Off?

Recent studies have shown that in practice, despite the new system, aspects of labels are still off-base (in terms of calorie counts, serving sizes, and weights). While labels aren’t off by much (between 8 – 25% according to the studies) it is enough to take note of, especially compared with the other part of this which is that “all calories are not created equal”.[2][3][4]

Beyond the labels being “fairly accurate” there are additional problems like labels not accounting for cooking and differences with the ways different people conserve, store, and use energy.

How we Measure the Calories in Food – More on Calories as a Measure of Energy

A calorie is a measure of energy. It’s like saying watts our joules. Most of the universe is technically energy, so it’s not THAT strange.

When we measure the energy in food, we measure its “calories”. Scientists burn the food to determine calories for the nutrition label on the back of the box, the harder it is to burn the more calories the food has.

When we digest a food, we are “burning” the food and turning it into calories. In this way, calories are calories (as a measure of energy in food). There is a big difference between burning food in a lab and the way our body actually processes different types of food.

FACT: 1 food calorie equals one kilo-calorie, which is the amount of energy needed to raise 1 gram of water from 15 to 16 °C.[1]

How Our Body Breaks Down Calories

Our body breaks down the food we eat into energy (calories). Our body stores the calories in an “energy store container” in the liver, or when that is full in fat and muscle for later use. The unused parts of the food are disposed of as waste.

The way our body breaks down the calories, how many calories the process burns, what nutrients we get, and what sort of hormones and chemical reactions our body has all depends on what type of food we eat.

Because each food causes such a different reaction in regards to digestion, nutrition, chemistry, and calories stored “a calorie is a calorie” only in the strictest technical sense.

The Thermic Effect of Food

Different foods metabolize at different speeds, and that results in foods that take longer to digest burning more calories. By the time your body is done burning the calories and digesting food only X% of the original calories is left over. This alone proves that a calorie in isn’t a calorie stored.

This is the thermic effect of different macronutrients according to one study:[3][4]

  • Fat: 2-3%.
  • Carbs: 6-8%.
  • Protein: 25-30%.

NOTE: Thermic effect varies depending on the type of carb, the type of protein, and what food we get the macronutrient from. The above are estimates from a study on the amount of energy it takes the body to process macronutrients.

Nutrient Rich Foods and Thermally Difficult Foods Make You Feel Full

Different foods cause different hormonal reactions. Protein fills us up; fiber does too, and so does ice water for that matter. Meanwhile, fructose spikes insulin and releases hormones that make us feel hungry and tell our body to store fat. Each macronutrient has very different effects on hunger and how we store fat; a lot of this depends on the exact balance of nutrients and macronutrients in the food.

Each food we eat has different psychological effects related to mood. Also, some macronutrients like sugars and simple carbs make you retain water, so even your physical appearance can differ due to food types.

 

 

The Difference Between Sugar, Fats, Simple Carbs, Complex Carbs, Proteins, and Fiber (Macronutrients)

Below we break down the difference between each macronutrient type (carbs, fats, proteins, fiber) and discuss its pros and cons in regards to calories.

Sugars (simple Carbs)

Simple carbs are sugars including table sugar, fructose, lactose and more. Sugar is an empty calorie, but sometimes it comes side-by-side with nutrients (such as in fruit). Although sugar has low nutritional value, your body can store it as energy easily, and thus it is good for energy purposes.

The Types of Sugar

Even though all sugar is essentially the same, there are actually a few different kinds. In simple terms, they are Fructose (fruit sugar), Glucose (fruit sugar), Galactose (sugar from milk), Lactose (sugar from milk), Maltose (grain based sugar), Sucrose (from sugar cane and some fruits).

Fructose Versus Glucose

Glucose and fructose are the main sugars we eat. Your body reacts far better to glucose than fructose. For instance, fructose can only be properly metabolized in the liver and fructose doesn’t satisfy our hunger centers and triggers hormones that make us hungry.

Natural Sugar Versus Processed Sugar

As you can see all those sugar types occur naturally. Often in the modern day, we don’t get naturally occurring sugar, we get lab-made sugar where sugars are refined from corn or rice. They aren’t inherently worse, but natural sugar can have minerals that refined sugar doesn’t (or only does because they are added back in). So apple juice with fructose and soda with corn syrup aren’t “the same”.

Is Sugar Bad?

No sugar is bad on its own, with other food types, in moderation. In nature sugar always comes in a wrapper of complex carbs and fibers, and it’s scarce enough to where one isn’t eating sugar all the time. In modern society sugar comes in liters of soft drinks. The amount of sugar we drink in the modern day far exceeds what we need. It is one of the main causes of dental problems in western society, and it’s a nightmare for diets.

Why is Sugar Bad for Dieting?

Sugar (especially fructose and processed sugars) spikes your insulin if not padded with fiber; it also triggers ghrelin (a hunger hormone). Spiking blood sugar tells your brain that you are starving. Sugar causes the munchies; it also tells your body to store fat. Since sugar is so easy for your body to digest, it thinks it’s should store as much sugar as it can.

[Semi-] Simple Carbs

Next, we have what we can call semi-simple carbs (this is not a technical term). Simple carbs are technically sugars, but for our purposes we will also include what we can call “semi-simple” carbs like pasta, rice, and fruits without lots of fiber. While these are mostly technically complex carbohydrates, they are about as close to sugars as we get while still remaining a food (and thus for diets we shouldn’t be too quick to consider a pretzel in the same family as broccoli). These semi-simple crabs can have lots of nutritionally positive values, but like sugar, your body stores “semi-simple carbs” easily.

Are Semi-Simple Carbs Bad?

Semi-Simple carbs like pasta are great for energy. Unlike sugar they typically have nutrients, and often contain a bit of protein and fiber. As we will find out shortly, protein and fiber slow down digestion and prevent blood sugar from spiking.

Complex Carbs

Complex carbs are things like grains, beans, veggies, and some fruits. Essentially anything that isn’t meat or sugar is a complex carb. They similar to simple carbs but typically contain more nutrients and more fiber.

Are Complex Carbs Good?

Complex carbs are generally one of the healthiest things you can eat. They are relatively easy for your body to break down, are chock full of nutrients, and low calories.

Fiber

Fiber is contained in foods like oats, nuts, prunes, kale, and other “roughage”. We seldom eat a fibrous food on their own because our bodies have a difficult time processing fiber into calories. The body’s attempt to digest fiber usually burns calories rather than storing them. This aids the digestive process and slows down the bodies absorption of other foods.

Is Fiber Good?

Fiber is beneficial for digestion and weight loss, but only in moderation. The reason an apple doesn’t make you fat is that it has fiber. The thing that makes complex carbs complex is fiber. Fiber’s importance can’t be underrated.

Proteins

Protein is found in meat, some vegetables, nuts, and seeds. Protein is digested slowly and often comes in nutrient rich foods. Protein foods contain essential amino acids, look for foods that are “complete proteins”.

Is Protein Good?

Protein is great because unlike the rest of the calories it naturally can be used to build muscle. Your body can’t replace the proteins you need to build muscle so you must get it from food. That said, proteins, especially meat are hard on your digestive system. They can help to slow down the digestion of other calorie types, but over time eating a diet too heavy in meats can lead to digestive problems.

Fats

Lastly, we have fat. Fat is primarily found in animals and oils. Fat works like sugar; it can have nutritional value, but (essential acids aside) it’s only good in moderation.

Is Fat Bad?

A little bit of fat goes a long way. Just like sugar, it should be eaten with other calories. It’s very easy for your body to store, but ultimately it’s better than sugar because it doesn’t spike insulin as much.

Conclusion

A calorie is a calorie, but only as a measure of energy. Outside of this how we store calories is completely dependent on the mix of fats, sugars, carbs, complex carbs, fiber, and proteins in our food and importantly the nutritional value of the food.

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