Are all calories equal?

Want to see people lose their minds and attack each other?  Just tell a random group of people that all calories are equal.  Then run away!

While you're fleeing for your life, this mob of unruly "calories are king" or "food quality is king" factions will take their sides.  Like a nutritional Lord of the Flies, be prepared to see things get real. And of course, once emotions are pulled into a debate, most logic and rational thinking go right out the window. Be prepared for real evidence to be in fact just anecdotes.

Which brings us to the dividing line when it comes to comparing calories.  I come across most people interested in health, fat loss and strength to not really think about calories too much.  Sure, they might flip over a box of cereal to check out the carbs or how much protein is in a Quest bar, but they don't have a lot of context for how those calories fit into their nutrition. They might not think about the context of how many meals per day they eat, how much of those calories are protein and if their training requires calories to change at all.  It's kind of like buying a new might kick the tires and ask about the warranty and gas mileage but you don't really know much under the hood.

And that is fine.  Most people don't need to. In fact, they just need a baseline level of knowledge and a discerning ear and eye for B.S.  Remember how you got a recommendation for a car manufcturer when you were younger (like I did from my dad) and you feel "safe" with that choice?  So dad says Honda is always a great choice so I might always lean towards that make.  Maybe a fit friend recommended Paleo so it feels safe.  

This is where emotions enter the fray and mess everyone up.  Imagine this: "saying Honda sucks is like saying my dad sucks.  How dare you, I will not stand for this"!! This is a problem I run into with coaching nutrition clients, asking them to eat more protein, less boxed food, more carbs, less carbs, whatever is the equivalent of asking them to buy a Ford Pinto, they can't even imagine a world in which that makes sense.

In my spiel to clients, I end up giving rational, scientific and anecodotally (because it still matters) evidence for what I want them to do.  For some that is enough, others need to actually trust you for a few weeks or a month and then see how they feel about those choices.  Ever have your car in the shop and you get a rental that you might never consider buying?  But then after a week of driving it around, you're like "dang, I kind of like this car"?  Yeah, that's what I ama sking....just test drive it for a bit if you don't believe me, then lets see.

Seriously though, what is a calorie?

A calorie, in it's truest form is this:

A unit of heat energy.  One kilocalorie (1,000 calories) is the amount of energy it takes to heat one kilogram of water 1 degree Celsius. 

So if this is simply thermodynamics, shouldn't it hold true that all calories are the same?  Isn't it just measuring heat which would be consistently measured despite the food being used? It would if we our bodies were just bomb calorimeters, which scientist use to conduct these experiments.  But we're living breathing organisms with digestion (which requires enzymes, bacteria, gut transport), immune function, adaptive thermogenesis and other peripheral factors.  Most of the peripheral factors like sun exposure, sleep, food quality and others probably impact which tissues favor those calories rather than how many calories are expended.  But it does still impact the outcome since people wouldn't care about calories as much if they all went towards muscle gain.  Remember, context?

We tend to view calories in a reductionist manner.  In the grand scheme of things, you can do pretty well just focusing on calories.  If you know you're general maintenance calories then you can create a deficit or a surplus and see a pretty well predicted outcome. This doesn't account for how well that deficit or surplus turns out though, since all the above factors contribute to the quality of that outcome. You know the old adage of a pound of fat contains about 3.500 calories, so creating a 500 calorie deficit would result in a theoretical pound of fat loss per week.

This does hold true from the 1,000 foot view and will result in fat loss if this deficit is held constant. But time and again, clients don't see that linear progress even when the math works out.  

It's not just math

Holding true to that calorie deficit is like saying a dollar is always a dollar.  It's true in the sense that if you hold a dollar in your hand, it is always the same legal tender.  But a dollar isn't always worth the same in terms of what it buys you, is it?  Inflation, the stock market, interest rates and taxes all impact how much that dollar actually gets you.  In a hypothetical sense, I believe this example gives a truer context to what a dollar is worth.  True, like a calorie it always equals the same.  But the exchange of that dollar (or calorie) has multiple factors influencing it.

Calories being pretty equal is why people can lose weight on a myriad of diets.  In the end, a calorie deficit will result in weight loss and we see that whether people do Intermittent Fasting, Paleo, Zone, low-fat or any single diet in existence.  When you look at the common factor, the calorie deficit is always hiding in the details.

Enter digestion

Quick fact: did you know your digestive tract is actually external?  From mouth to anus, your digestive tract is a closed system that exists as an external pathway.  It's why it is colonized by bacteria while internal (blood, bone, organs) are not. This is also why the digestive tract is so selective, it needs to act as a regulator of what comes in so the system is not overly stressed or threatened.  But because it is so highly functioning and requires a vast amount of variability in what it can digest and absorb, it requires a huge amount of energy.

This energy requirement for digestion is where we get differing end amounts of energy yielded.  Yes, a calorie is still providing the same amount of energy, but digestion is using varying amounts of energy to digest different calorie sources. 

Lets check out energy requirements for digestion of different food sources:

Food Source% calories used in digestion

We can see that each food source has it's own general amount of energy from digestion needed to render it useable.

I use these examples pretty much every time I discuss raising protein or defending carbohydrates to a client.  I want them to understand it's not just my personal preference that drives these decisions.  People will argue that carbs drive insulin which in adbundance can cause some insulin resistance issues but remember, we're not talking about 500g carbs per day, and even if we were, in a calorie deficit the game changes.

Lets put that away for now though and focus on calories expended in digestion.  Below I will give a breakdown of three different macronutrient mixes and how the total energy taken in results in different energy outcomes based on digestion (based off the top end ranges).


Macronutrient MixTotal Calories EatenAdjusted for Digestion: ProteinAdjusted for Digestion: CarbohydratesAdjusted for Digestion: FatTotal Calorie Outcome
15% protein, 50% carbs, 35% fat250026211258312218
25% protein, 25% carbs, 50% fat250043756211872186
35% protein, 40% carbs, 25% fat25006129005932105

Interestingly, Dr. Jose Antonio has found in his high-protein research that individuals consuming upwards of even 45% of daily calories from protein see fat loss, even when consuming up to 400 additional calories per day.  Of course, the thermic effect of food plays a role as we see above but the other unaccounted for calories expended are hypothesised to come from N.E.A.T.  Non-exercise Activity Thermogenesis (N.E.A.T) is the calories you expend doing all the movement during your day that is not exercise related and is perhaps the most widely variable calorie expenditure among individuals.  In some studies, over-feeding subjects 1,000 calories per day results in weight gain while some see no weight change or even weight LOSS.  N.E.A.T is adaptable and will increase or decrease based on calorie status, stress and other factors. But it is largely genetic and neuronal meaning you don't really have conscious control over it.

Dr. Antonio posits that the extra calories burned when protein is raised comes from protein's affects on N.E.A.T, essentially turning it up.  So while maybe half of those extra 400 calories were expended through digestion, the other half were most likely expended through an increase in N.E.A.T like fidgeting, tapping and walking around.

When we combine these two factors and say eating a more thermogenic macronutrient ratio, you might see a daily increase in energy expenditure from 100-400 calories.  Lets play it safe and just say it's an average of 250 calories (though this is just for my example).

Playing the long game

Taking that increased expenditure of 250 calories per day and extrapolating it over the course of just one month, we see 7500 extra calories burned.

A year? That's more like 91,250. If that all came from fat it would result in 26lbs of fat tissue burned.

Now, you could add in 30-45 minutes of cardio every day instead to try to expend the same 250 calories but that's more time, stress and ultimately spinning your wheels. And the reason you want to avoid chronically adding more exercise to expend calories is because adding lots of exercise usually results in a DECREASE in N.E.A.T.  This is because the chronic exercise is a consistent low-grade stress that the body wants to adapt to.  It wants to be able to do the cardio with minimal impact on the system.  And if the body is forced to complete the task using extra calories, it will make up those calories through decreases in N.E.A.T.

The reason training with weights doesn't result in quite the same adaptation is because with weights you can add load, reps or change the rest period.  You can tinker with adaptations the body needs to make to keep pushing progress.  But the same 'ol cardio everyday is easily adapted to and quickly results in stagnation.

Getting to the bonus level

Maybe you've tackled the big stuff above and realize that hitting the gas on the system through dietary manipulation works way better than just pushing exercise.  But we can go even further to make that calorie work so well for us.  We can ensure:

  • Consume 10-15g fiber per 1000 calories.  Not only does fiber have fewer calories per gram than carbs (just because some is indigestible) but anything that improves digestion and blood sugar control will probably improve your dietary adherence, satiety and fullness
  • Consuming adequate Omega 3-s.  Dr. Ben House likes to think of adding Omega 3s as "free calories" simply because they upregulate the mitochondria and fat oxidation within the cells, not to mention imrproving cortisol, heart rate and muscle cell insulin sensitivity and upregulating mTor 

These two additions alone help shift the calorie balance back in your favor not to mention how much better they make you FEEL.  When we combine that with the overall health benefits and the edges they give us to building muscle and burning fat, it's hard to pass these up.

All of this goes to show that putting food in your mouth is a pretty A to B experience.  But the mechanical, chemical and electrical machinery inside your body is not such a linear line.  No system change without impacting another system and you are an organism that is constantly adapting to the environment inside AND outside to keep homeostasis as much as possible.  We can improve our relationship with these environments by choosing foods and macronutrient compositions that push all these factors in positive directions.

If calories were all that really mattered you could drink protein powder, eat Ring Dings and make sure you were in a calorie deficit, netting the same results as someone eating a vegetable, fruit, whole food and balanced fat based diet.  But you know it wouldn't work out the same without even doing this experiment. It's because you aren't just a calculator with a personality, you are an incredibly adaptive being that IS impacted by quality as much as quantity. 

So it makes sense to act like one.