The Thermic Effect Of Food

Is a calorie really just a calorie? According to the concept of the thermic effect of food, not exactly.

Whether you’re trying to burn fat or build muscle, if you’re serious about either one then you are keeping track of your caloric intake. If you’re even more hard core, you have goals in terms of how much of each macro-nutrient you need to eat in order to reach your desired caloric intake for your specific goal.

The argument that a lot of people make is that all that is important is the amount of calories you’re eating. If you’re trying to burn off some extra fat then you need to be in a caloric deficit. This is when calories eaten is less than calories burned. When building muscle the opposite needs to happen, you need a surplus. More calories consumed than used for energy. I should point out that those last two sentences explain why it’s pretty much impossible for you to burn fat and build muscle at the same time, but that’s a post for another day.

So it’s simple, a calorie is just a calorie. To lose weight eat less, to gain weight eat more. Simple, end of story.

Well not quite. Turns out a calorie is not just a calorie. The macro-nutrients; Protein, Fat and Carbohydrates all have a different thermic effect when consumed. Thermic what?

When you eat food it takes energy for your body to break those foods down. Digestion requires fuel. Protein, Fat and Carbohydrates each require a different amount of energy (calories) to be digested. It would stand to reason that 3,000 calories eaten from foods that require more energy to be digested would be different than 3,000 calories eaten from foods that require less energy to be digested.

To say it another way, some foods will burn more calories than others after they’ve been eaten.

The Thermic Effect of Food: Macros

Here is a breakdown of popular estimations of the thermic effect of each macro-nutrient

  • Protein 20-30%
  • Fat 0-5%
  • Carbohydrates 5-10%

These percentages mean that up to 30% of the calories eaten from protein will be burned off when high protein foods are digested, up to 5% for fats and 10% for carbohydrates. To better explain what this means I’m going to use a 3,000 calorie diet that is structured based on the current recommendations by the FDA then compare it to a typical high protein diet.

FDA 3,000 Calorie Diet

  • Protein 25% = 3,000 x .25 = 750 Cal / 4 (calories per gram of Protein) = 188g Protein
  • Fat 25 % = 3,000 x .25 = 750 Cal / 9 (calories per gram of fat) = 83g Fat
  • Carbohydrates 50% = 3,000 x .50 = 1,500 Cal / 4 (calories per gram of Carbs) = 375g Carbohydrates

Using the above estimations for TEF for each macro, the total amount of energy used to digest these 3,000 calories would be…

  • TEF Protein = 225 Calories
  • TEF Fat = 38 Calories
  • TEF Carbohydrates = 150 Calories
  • Total TEF W/ FDA Diet = 413 Calories

3,000 Calorie High Protein Diet

  • Protein 45% = 3,000 x .45 = 1,350 Cal / 4 (calories per gram of Protein) = 338g Protein
  • Fat 25 % = 3,000 x .25 = 750 Cal / 9 (calories per gram of fat) = 83g Fat
  • Carbohydrates 30% = 3,000 x .30 = 900 Cal / 4 (calories per gram of Carbs) = 225g Carbohydrates

Now let’s add up the TEF for the high protein diet

  • TEF Protein = 405 Calories
  • TEF Fat = 38 Calories
  • TEF Carbohydrates = 90 Calories
  • Total TEF W/ High Protein Diet = 533 Calories

The difference between these two diets comes out to be only 120 calories per day. For most people that may not seem like a significant amount. While I agree it’s not a lot, every little bit helps if you’re trying to get ripped, especially if you’re getting ready for a show.

A typical contest prep takes about 16 weeks (yes some people a lot less, just humor me). Over the course of a 16 week contest prep 120 calories a day comes out to be 13,440 calories. Or about 4 pounds of body fat. If you’re a competitor than I don’t have to tell you how big of a difference 4 pounds of fat will make come show time.

Is a calorie just a calorie, not really. Calories from protein clearly require more energy to digest then calories from fat and carbohydrates. Does that mean that you should eat nothing but protein? No, fat and carbohydrates are essential nutrients, we need them for a number of reasons.

However, if you’re trying to burn a little extra fat or you’re getting ready for the stage, increasing your protein intake to 1.5-2 grams per pound of body weight might not be a bad idea. At the very least try to eat at significant amount of protein at every meal to optimize the thermic effect.

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