In our quest to lose or gain weight there are a lot of different things we hear that on the surface seem to make sense. These things seem to draw a line in the sand for us in what should work and what doesn't. The one of these I'd like to discuss today is the ~3500 calorie per pound myth.
If you haven't heard it it goes like this, roughly 3500 calories is the equivalent of one pound of body weight. Therefore if you want to lose one pound per week you's need to cut your diet by 500 calories per day or burn an additional 500 calories per day through exercise.
This makes sense right? Of course it does. But like all on paper diet science, it basically never works. The question is why not?
FIrst lets go into a few of the obvious reasons. The first is that we don't actually digest all of our food. This means there is unused energy that comes out in our feces. That means if you eat 500 calories less, you weren't absorbing all of those 500 calories anyway so its not really a full 500 calories deficit.
Next, digestion takes energy. Depending on the type of nutrient it can be more or less but its on average about 10% of our energy intake is used trying to digest the food. So once again, eliminating 500 calories would only really be like eliminating 450.
Next, different macro-nutrients (protein, fat, carbs, fiber, alcohol) absorb at different rates so depending on what you're eating, you may absorb more or less nutrients.
Water weight is another big one. The average body can shift weight easily by 10-15 pounds of just water weight and many times, changes in our diets will actually trigger water retention or gain. So even though we may have lost tissue, it will never show on the scale because its replaced by water. This is why some people can workout for weeks and lose no weight, then all at once they seem to lose 8 pounds. Its not magic, its water.
Ok so many of you are now asking what happens if you were to burn an additional 500 calories instead of just changing the intake. Well, there's more to the energy equation than just intake and output. There are actually four different types of output. Resting or basal output Exercise output (thermic effect of action/TEA) Non-Exercise Activity Thermogenesis/NEAT Food output (the calories we burn to eat and digest/thermic effect of food/TEF) The problem with simply increasing output in one area is that it can effect the output of another. For instance, if you were to go for a run to burn your 500 calories, you may find that you don't move as much as you would have when you get home because you're tired. Therefore you burn less NEAT calories which offset the 500 you burned. There are many other things as well but my point is that no matter what you do, you'll never be able to get it down perfectly in the equation so you can't expect perfect results. Fat Vs. Muscle I would say the biggest flaw however is that its just wrong. Its not bodyweight that equals roughly 3500 calories' it's fat. Muscle and fat are not the same. Fat may be 3500 calories but muscle is only about 600 calories per pound. That means, that same 3500 calories could burn one pound of fat or 5.83 pounds of muscle! Of course no one is going to lose just muscle or just fat but following this logic, if you're losing more than 1 pound of weight per week with a 3500 calorie deficit, you are losing your muscle! The sad thing is that because of water weight issues, you may not even know it until its too late. The moral of this story is that when you're dealing with the body, nothing is concrete. We are not static beings and not even the equations of life seem to stay the same for us. Until next time, Kris PS: If you want more information on this topic, there is a great article called The Energy Balance Equation
Changes In Output
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