I had a great question in the gym the other day. One of the members asked if a calorie is just a calorie, that how even I figure I can go to macDonalds. So i passed it on to TBI’s Director of Nutrition. Man did I get blasted. thought you too would enjoy it.
Sorry , just not the same: Fred
By Filipe Teixeira-P-PTS, TBI-CSN
About your question, when you talk about your body a calorie is not a calorie.
When you state that sentence you refer to the 1st law of thermodynamics, however your body is not a pump calorimeter.
Let me give you a straight example, do you really think using carbohydrates is the same as using proteins?
They both have around 4kcal calorimeter value, however using protein in the form of aminoacids in oxidation also costs energy.
Every time you use aminoacid conversion into the glucose-alanine cycle it require around 6 ATP molecules to use 1mol of Alanine. So although they both have the same energy in the calorimeter they are not equivalent in human machines. Using energy also costs energy and that is well established in the 2nd law of TD, the dissipation law. Unlike the 1st law, the 2nd controls all the reactions in the human body. The 1st law is basically a book keeping law (the conservation law).I have an article about this in portuguese, if you use an isocaloric diet with more carbohydrates than protein you will have a net energy balance higher than if you use the same calories using protein more, this is why high protein diets show metabolic advantage in several studies.
Proteins have a much higher thermogenic effect (25-30%) than carbohydrates (6-8%), this by itself might explain the metabolic advantage of high protein diets in fat loss. So like the article from Dr. Feinman states, stating that a calorie is calorie violates the 2nd law of thermodynamics.
Look into macronutrient content and don’t count calories. Your body is not a pump calorimeter, it does not burn anything, it works by controlled nuclear power. Biochemistry does not flow only in one direction, it has multiple metabolic passways that change your calculations when it comes to energy.
1-values for calorimeters only stand for calorimeters, not human body.
2-Standard deviation is huge when it comes to different kinds of fats burned in the calorimeter, proteins or even carbohydrates. So not a precise method at all.
3-Calories are calculated on pump calorimeter at constant volume which does not apply to human body. Work in these calorimeters is 0 which is not true for the human body. We should talk about enthalpy and not calories, since enthalpy is calculated at constant pressure and not volume. Therefore kJ should be the unit used not kcal.
So how you see there is a lot to be said about calories, thermodynamics and human body. If calorie is a calorie why do you spend more money on high octane gas? Same calories, way different work capacity…