“Is a Calorie Really Just a Calorie?” By Dr. Mike T Nelson


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Mention the word “calorie” to a fitness professional, grab some gluten-free popcorn, and watch the chaos ensue.

On one end of the spectrum, we have a group that defends the use of counting calories and argues that it solves all of your problems with body composition.  Therefore, you must count all ‘em calories down to a gnat’s ass.  Calories are the only thing that matter, and you just need to either burn more or consume less.  This is followed closely by a muttering about the law of thermodynamics.  It is a law, for heaven’s sake, and must be right!

On the other end, we have a group who argues that calories are outdated and do not describe the complexities of human metabolism.  Therefore, don’t even worry about them!  You’re an idiot if you spend your precious waking hours counting them.   Stop it!  Go to the gym and don’t collect $200!

Who is right?  If we put them up against each other in a grudge match of wits, who would emerge as the winner?

Calorie Confusion Conundrum

You can now see why the average person looking to deflate their spare tire is utterly confused.  If we can’t agree on something as basic as calories, are we doomed to spew confusion to the masses as the obesity rates climb higher than a slam dunk from Lebron?

The short answer is that both philosophies are too much of a simplification.

Give me 2 minutes and I can find a horde of people that got lean by never counting a calorie.

Give me another 2 minutes and I can find the same number of people who did count calories and were equally as lean.   Hold the phone as I submit this study to PubMed…..  OK, I’m back (insert sarcasm here).

Enter the Geek – Thermodynamics 101

Both sides come back and site thermodynamics at the heart of their argument.  I always like to ask them what the first law actually says, which is followed by lots of “hmmms” and “uhs” and the blurting of a seemingly random number.  Hint, there are ally 4 laws and the zeroth was actually added last.

The laws are as follows.

Zeroth law of thermodynamics – If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

First law of thermodynamics – Energy can neither be created nor destroyed. It can only change forms. In any process, the total energy of the universe remains the same. For a thermodynamic cycle, the net heat supplied to the system equals the net work done by the system.

Second law of thermodynamics – The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.

Third law of thermodynamics – As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

I am pretty sure both groups use of the Laws of Thermodynamics does nothing more than to confuse the piss out of people.

Not to mention, most who argue about it never once took a friggin’ thermo class nor did the do any research in that area.  If I wanted to get all huffy about it, I could point out that I did suffer through those classes for my MS in mechanical engineering and even published research in the IEEE journal on heat transfer in a monkey head.    I am not an expert in the field by any means, although I have a pretty good grasp of the math behind it in addition to physiology.

But don’t believe me, here is what Dr. Feinman stated

“Our major point here is that there is more than one law of thermodynamics and that a more accurate understanding of the role of the second law shows that differential weight loss is not inconsistent with any physical principle.”   (Feinman & Fine, 2004)

No physical laws were violated.  The universe is still intact and you can sleep well tonight.

Second Law, First Law, Who Cares

If I ate my Wheaties in the morning and I magically have 3 extra hours in my day to get into pissing matches on the old interwebz about this topic, I would throw out that the first law of thermodynamics is not really what matters as much regarding calorie confusion.  It is actually the second law that is the most helpful.

Keep your arms and legs inside and buckle up partner as we embark on an uber-brief crash course in thermodynamics.   All aboard the pain train!

The first law is primarily just a book keeping law.  Energy is neither created nor destroyed and just changes forms.  Keep in mind that this is applied across the universe, not just to your body!  This law is not violated and is also generally not too useful unless we look at a closed system such as a metabolic chamber.   It does not tell us much about free living humans.

The second law states that entropy (a simple measure of disorder) increases over time.  It is this law that drives chemical reactions (Feinman & Fine, 2004).  Metabolism can be thought of as a crap ton of chemical reactions.  The second law came about from the investigation of machines since they are not 100.00% efficient as some of the energy is lost as heat.  Hmmmm, sounds like the human body.  If your body temperature reaches room temperature, you are dead which really impedes your fat loss progress.

Enough Physics!!

To summarize so far:

  • The laws of thermodynamics are real and not violated.
  • It is actually the second law regarding entropy that is the most important.

The Disconnect

Where people go off the rails is to assume that either counting calories works for everyone or that you don’t need to do any of that stuff.

According to the second law, there is not a super nice and linear relationship between the calories you eat and how many of them go to your love handles.   Rarely is anything in physiology nice and linear (Thomas, Ciesla, Levine, Stevens, & Martin, 2009: Feinman & Fine, 2007).  Just like the efficiency of machines will vary, humans are similar in that regard it is not a simple linear equation.

Unlike a car, you want to be more inefficient and throw off more energy as heat for fat loss since that energy is then not stored as fat.  This is where the huge disconnect happens. Thermodynamics is still valid; it is just not that simple to calculate all the inefficiencies that go into metabolism in the average person.

True, we could lock you up in a metabolic chamber where all of this is accounted for; but that does not mirror real life where the decision to eat skittles may predispose you to eat more calories later.  Calories in affect calories out and vice versa.  Unless you are in prison, you live in an open system where calories in and calories out fluctuate constantly.

This Is NEAT

If you spend enough time wander the aisles in Walmart like a lost puppy, this next statement will not seem true, but I have S.C.I.E.N.C.E to “prove” that it is real.   Humans have all sorts of counter regulatory measures that jump into effect in an attempt to not let you get fatter.  One of these is NEAT aka non-exercising activity thermogenesis.  In short, you tend to start moving around more and even fidgeting away the extra calories.  The downside is that this may not be enough to burn off the extra calories and thus some gets stored as fat.  This rate of NEAT varies widely from one person to the next (Levine, Eberhardt, & Jensen, 1999).

“Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding”  – Dr. Levine

In a review by Levine 2007, he also stated “NEAT varies between two people of similar size by 2000 kcal per day because of people’s different occupations and leisure-time activities.”

Eeeeek gads man.  There is a massive variation from one person to the next.

In another study by Trembly et al. in 1992, they over fed subjects by 1,000 kcal for 100 days.   They found that it did induce an increase in the cost of trying to maintain weight, but even then two-thirds of the excess was stored as ugly body fat. (Tremblay, Despres, Theriault, Fournier, & Bouchard, 1992).  The punch line is that your body will increase your metabolic rate, thus burning more calories when you overeat.  Sadly, at some point it is not enough to keep you lean, and you will gain weight.  It is not a simple linear correlation though.

What to Do

This is one of my new favorite quotes:

“Telling an obese person to exercise more and eat less is like telling a depressed person to have a nice day” –Dr. Stu Phillips

If just telling people to eat less and do more exercise worked well, we would not have such a rapidly escalating rate of obesity.  However, counting calories in only does not guarantee you to be super lean as that is only half of the equation.  Further attempts to record keep your way into accounting for calories burned is not only quite hard, but many equations are not super accurate and do not account for counter regulatory factors such as NEAT.

Yes, you can count calories and see great results.

You can paradoxically not count them and see great results too.  Just because you opted not to count them does not mean they don’t exist.

The calories do matter, but whether you decide to count them or not is up to you.

My bias is to do the least amount of work first for the greatest potential change in body composition (metabolic leverage).  The 3 step process is

1)      Eat more protein.

This involves bumping up protein to around 0.75 grams per pound of bodyweight first.   Protein has several advantages and the main one is satiety making it hard to over eat.   And even if you did ramp up your protein super high, a new study by Dr. Antonio et al. 2014 showed minimal changes in body composition when subjects ate a whole bunch of protein.

2)      Go lift stuff.

Add some weight training for 3-4 sessions per week focusing on compound lifts with increasing volume.  You can add in some interval sprints if that tickles your fancy.

3)      Be aware.

Record what your put in your cake hole first so that you are conscious of it.  Work to eat more whole foods first that have minimal processing.  No foods are automatically off limits though.    Everyone needs to stop with the “good” vs “bad” food or labeling certain eating “clean.”

Once you have done 1-3 consistently for 4 weeks, then you can start to sweat the details and start counting stuff if you please.  There is no need to major in the minors to start.


  1. Thermodynamics is real, and no laws have been broken.  Cold fusion is still not real however.  I have my doubts about Bigfoot, and the Loch Ness Monster is a lie.
  2. According to thermodynamics, calories in and calories out is true.   If you agree, give yourself a gold star.
  3. How much you eat will generally determine how much weight you gain or lose.
  4. What you eat will generally determine the composition of that weight (fat or lean body mass).

Follow the 3 steps above to get started today.  In the time most spent arguing about calories, you could be significantly leaner.


Antonio, J., Peacock, C. A., Ellerbroek, A., Fromhoff, B., & Silver, T. (2014). The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Journal of the International Society of Sports Nutrition, 11, 19-2783-11-19. eCollection 2014. doi:10.1186/1550-2783-11-19 [doi]

Feinman, R. D., & Fine, E. J. (2004). “A calorie is a calorie” violates the second law of thermodynamics. Nutrition Journal, 3, 9. doi:10.1186/1475-2891-3-9 [doi]

Feinman, R. D., & Fine, E. J. (2007). Nonequilibrium thermodynamics and energy efficiency in weight loss diets. Theoretical Biology & Medical Modelling, 4, 27. doi:1742-4682-4-27 [pii]

Physics for Idiots, http://www.physicsforidiots.com/thermodynamics.html, accessed June 25, 2014.

Levine, J. A. (2007). Nonexercise activity thermogenesis–liberating the life-force. Journal of Internal Medicine, 262(3), 273-287. doi:JIM1842 [pii]

Levine, J. A., Eberhardt, N. L., & Jensen, M. D. (1999). Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science (New York, N.Y.), 283(5399), 212-214.

Thomas, D. M., Ciesla, A., Levine, J. A., Stevens, J. G., & Martin, C. K. (2009). A mathematical model of weight change with adaptation. Mathematical Biosciences and Engineering : MBE, 6(4), 873-887. doi:10.3934/mbe.2009.6.873 [doi]

Tremblay, A., Despres, J. P., Theriault, G., Fournier, G., & Bouchard, C. (1992). Overfeeding and energy expenditure in humans. The American Journal of Clinical Nutrition, 56(5), 857-862.