Does the caloric equation really add up?

Einstein said "No amount of experimentation can ever prove me right; a single experiment can prove me wrong." - Albert Einstein

I know he said it because I got it from the internet and therefore it is true.... well likely true (ish).

The internet (and just about every text book on fitness or nutrition as well) holds this little gem too:

In this blog I think I'm going to be saying 'the emperor has no clothes!'  I just don't buy this thing anymore and I don't think Einstein would either.

Here's a list of just some of my problems:

Issue #1

The equation proposes that if you put a calorie in your face you get a calorie of energy in the cell. That is 1 calorie ingested is eventually 1 calorie of ATP production.  To put it another way -  if I suggested all students who enrolled in university became graduates you would inherently suspect I was bonkers. Going into a lecture theater does not guarantee you will all learn or respond the same way, and graduate.  All you can really say is that 'the student entered the building'. This is true in the body also. Ingesting a calorie doesn't guarantee breakdown, absorption, metabolic inclusion, cellular transportation and use. A calorie that goes in the face is not a calorie of energy every time. In fact given all the steps in the chain there is significant variation amongst all of us and even within us at various times.

Not to be a problem generator - here is my proposed correction.  "A calorie in the face is only a potential calorie on the hips"

Here's some evidence of equal calories going in the face but different weight loss occurring;

Low GI (glycemic index) diets reduce body weight more than high GI diets.  If the caloric equation held this shouldn't be true. A calorie, whether high or low GI, should behave as a calorie - it simply doesn't and there are a number of reasons for this with low and high GI food (maybe fodder for a later blog!)

Or more succinctly in a graphic for those who like them (note this is on rats because you can't get people to do what they are told for 32 weeks that easily - ask my wife!):

So, the mechanism here seems to be the fibre and likely the other nutrients (flavanoids, anti-oxidants, vitamins etc) packed in to low GI foods.  We can quickly see that a calorie is not a calorie because the cost of digestion (thermogenic cost of moving that bulk through the digestive system), binding of fibre to starches, bacterial activity and type, all change because of the type of food that calorie is ingested.  Boom - calorie equation 0, Steven 1 ;)

Issue #2

Genetically we digest and metabolise foods differently. Calories are therefore predictive not absolute and to use them as dogmatically as we do is misleading.

Calorie expenditure is hugely variable between same weight subjects. The caloric equation suggests that caloric output can be nailed down the same way caloric input can be calculated by burning food and coming up with a face number.

Some examples

Just as we can't say all food is equal when it comes to calories, we can't say all exercise is equal either.  There is a stimulus and response relationship mediated by the individuals condition (genetics, training history, nutrition, hormonal state and much more). 

Running on a treadmill for an hour burns 700 calories for a typical 70kg male (and I think it also kills brain cells because it is THAT boring). The challenge here is the predictive nature of the measure. A very unfit 70Kg male without a lot of running experience will burn considerably more calories than a 70Kg marathoner. The idea is the work done can be calculated by the weight of the body carried over the distance in question. There is no consideration given to running efficiency, internal forces, training history, pre-exercise condition (such as fatigue), heat accumulation, footwear and so on.

The exercise principles we accept in exercise science go counter to the caloric equation in many instances. Lets take individuality for example. This principle holds that each individual responds differently to the same stimulus. So, if I was to do an exercise bout, and my wife did the same one, our responses during and after exercise would be different. Makes sense doesn't it given the genetic differences, the different physiological starting points for each of us, and the ability of our bodies to depart from and return to homeostasis and adapt.  The caloric output does nothing to address our principle of individuality rather treating all human physiology as the same.

The principle of trainability also falls foul of the caloric equation. This principle posits that each individual will adapt at there own rate. Some are faster at changing than others and therefore have better trainability. If we accept this principle in exercise then surely we must accept that any 'caloric change' will have a variable result but the caloric equation simply doesn't allow for that. The Caloric equation proposes that a deficit of 'x' calories per week will result in 'y' weight loss. It never does and yet we continue to roll out this equation in textbooks and advice.
If we were to venture down this path of removing the Caloric equation then what is the alternative explanation?

Well it may look more like cellular calories available versus cellular calories expended. Not what we ingest but rather the ATP equivalent available to my cells. Not what we expend but rather the cellular energy cost of all processes during the period. This is much harder to measure and to arbitrarily prescribe from. It's not as convenient despite it likely being more accurate.

A final note to my good physics friend. He argues with me that the law of the conservation of energy must be observed. This is the law that states energy is constant and cannot be destroyed it merely changes form. This is thermodynamics applied to a closed system.

I would say that this law is maintained in that any ATP energy that is provided by way of metabolism does enter the equation because it is now in the system (the cell). The body is not a closed system. The material entering the body has potential energy but that energy may, or may not, be realised in the cell.  If the energy did enter the cell it would count.  If it did not enter the cell but instead passes on by, then it hasn't contributed to the cell's net position and is therefore not included in the equation. Any consumed energy that does not get metabolised into a biologically usable form of ATP (i. e. Glycogen, Fat, Protein, Creatine Phosphate and Phosphagen) does not count. That means the physicist is happy and our model is more realistic.

Accepting that the Caloric equation might be a bit patchy is a first step toward a better view of weight gain or loss. The next question I'll be diving into is 'are all calories created equal'?