If you really want to start a catfight in the Paleo world, just raise the topic of calories. Is calories in, calories out a load of baloney, or is it the only legitimate way to lose weight? Do you need to count calories for weight loss? Does a ketogenic diet work because it automatically restricts calories, or because it provides some special metabolic adaptation?
As usual, the answer is complicated. And if we try to oversimplify it for the sake of a snappy catchphrase, we’re just making it harder to get to the ultimate goal: better health. So instead of getting caught up in black-and-white thinking about how calories either “count” or “don’t count,” consider that there are really two different arguments going on here:
As it turns out, that’s exactly what happens, and that’s probably why very intelligent people disagree so strongly on the calorie issue. Argument 1 seems to be true, in a certain very limited sense. But Argument 2, the “eat less, move more” prescription, is so oversimplified that it’s useless: it doesn’t even account for all the ways “calories in” and “calories out” can change. So the researcher who stubbornly insists that “calories count” is right, and the frustrated ex-dieter who couldn’t lose weight on 1,200 calories a day is also right. Calories are technically “true,” but human nutrition is so complicated that they just aren’t very useful.
Calories and the Laws of PhysicsLet’s start the foray into the science of calories by taking a good hard look at Argument #1, the claim that by the laws of physics, a calorie deficit is the only way to lose weight. This is the line you’ll hear endlessly repeated by obesity researchers and diet experts ‘round the world: “weight loss depends on a calorie deficit.” It’s called the Calories-In/Calories-Out hypothesis, or CICO for short.
The basic idea goes like this: by the physical laws that rule the universe as we know it, energy can’t be created or destroyed. It can only be transformed from one form to another. Calories are one unit of energy (if you want to get really precise, one dietary calorie is the amount of energy needed to raise one kilogram of water one degree Celsius). When you eat food, those calories either get used to do something (move your body around, maintain your body temperature, keep your heart pumping…), or stored as fat. No matter whether they come from protein, fat, or carbs, they must be either used or stored. They cannot magically disappear on the trail of the unicorns, or evaporate into thin air, or vanish at the full moon. If you’re gaining fat, it’s because you ate some calories and they got stored as fat. If you’re losing fat, it’s because some of those calories are coming out of storage and getting used for fuel.
This is usually delivered in that familiar tone of “Science says this, and that’s final” – with the implication that if you don’t believe it, you’re just being superstitious or unreasonable. But then again, we’ve also heard “saturated fat is bad for you” delivered in exactly the same tone. So does the CICO hypothesis actually deserve so much confidence?
Calories: The Other Side of the StoryThe main argument otherwise isn’t that calories are a lie, or somehow “false.” It’s that the typical story about “calories in, calories out” doesn’t account for how we use those calories, or why we’re driven to overeat calories in the first place.
Think of it this way: imagine your body is a train, where the people getting on are calories in, and the people getting off are calories out. So the more crowded the train, the more weight you’ve gained. Now imagine that one day, the train is really packed. You might turn to your friend and ask, “why is the train so crowded?” And if your friend is an annoying smart-aleck, he might answer, “because more people got on than got off.”
Everyone understands that that’s a ridiculous answer, and that’s not what you were asking for at all. You were probably expecting to hear something like “because it’s rush hour,” or something else that explains why more people got on than got off. But that’s what the CICO hypothesis does. Why did you gain weight? Because calories in exceeded calories out. This is technically true, but the question remains: what caused calories in to exceed calories out? It’s not nearly as simple as “you ate too much and/or exercised too little,” because there’s a lot more to the “calories in” than food, and a lot more to the “calories out” than exercise.
In other words, the insulin hypothesis (blaming excess carbohydrates for weight gain), and the food reward hypothesis (blaming addictive processed foods), and the lean-tissue hypothesis (blaming nutrient deficiency) all start from the premise that calories count. They just also argue that it’s a lot more complicated than that.
For example, take a look at this. It’s an explanation of the insulin hypothesis from Gary Taubes, one of its biggest champions. But even in this explanation, carbs don’t create fat out of nowhere. Excess carbohydrates raise the levels of a hormone called insulin, which directs calories away from the organs. Organs are the biggest calorie consumers in the body, so anything that stops calories from getting to your brain or liver is seriously reducing the number of calories out. With nowhere else to go, those calories get stored as fat instead. The question isn’t whether calories “count” or “don’t count;” it’s what causes them to be stored instead of used.
To put it in terms of the train image above, insulin would be something like a nasty conductor who prevents anyone from ever getting off the train. What Taubes is saying is that we need to find this one conductor and get rid of him, instead of focusing on the people – people who would like to get off the train, if only they were allowed.
There are a lot of problems with this idea – to start with, the number of perfectly healthy traditional societies who ate a lot of carbs and yet did not struggle with obesity. It’s not at all clear that the insulin hypothesis is actually useful for explaining what goes on in people who aren’t already diabetic. There’s probably no reason why healthy people should avoid carbohydrates, especially not if they exercise regularly. But for the purposes of this article, what really matters are the claims about calories.
Notice that the chain of events above does not include a step where insulin or carbohydrates manufacture fat out of thin air. This person is still gaining weight because they are storing calories as fat. The laws of physics are not violated. Calories in (food) still get either stored as fat or used for energy; the difference in this case is just that the person is storing more, and using fewer of those calories.
Calories: It’s ComplicatedThe take-home from the insulin hypothesis is that calories technically “count,” but what your body does with those calories counts more. And that was just the tip of the iceberg: take a look at some of the many other reasons why both the “calories in” and the “calories out” side of the equation are much more complicated than they first appear.
“Calories in” is not just the number on the Nutrition Facts panel. Like any other nutrient, the number of calories you actually get from your food depends on how many you absorb, not how many you put in your mouth. And that’s influenced by…
Taken to an extreme, this can cause some serious problems. You’ve changed “calories in” (by dieting), and you might have even increased “calories out” (by exercising) but your body one-ups you and decreases metabolism so drastically far that it makes up for all the starvation and the time on the treadmill.
So when you add it this all together, the equation is not just “fat gain/loss = calories eaten – calories burned on the treadmill.” “Calories in” are more than food, and “calories out” is more than exercise. In real life, it depends on all kinds of factors, some of which you have no control over and can’t even measure. If you took all those factors into account, then you could construct a useful weight-loss plan based on counting and measuring calories. But you can’t take them all into account – and that’s why calorie-counting fails, even though calories technically still count. In order to produce real-world weight loss, we need to focus on something else.
Objections to Calories-In/Calories-OutBefore moving on to Part 2, take a look at some of the common objections to the CICO theory, and why they’re not convincing.
But nobody eats precisely the same amount of calories every day.This objection is based on the idea that, if CICO is an accurate model, weight-stable people must be eating the exact same number of calories every single day. And of course this never happens: in the real world, calorie intakes vary a lot.
But this still doesn’t disprove CICO, for two reasons:
But I can’t lose weight even on _____________ calories/day!This may very well be true. But it doesn’t prove that calories don’t matter; it only proves that counting calories isn’t the best way to lose weight. Remember the insulin-resistant person above, who was gaining weight from eating too many carbs? That person could very well stay fat on 1,200 calories per day or even less. But it’s not because the calories didn’t count; it was because they were storing calories instead of using them. It’s true that thinking about calories won’t help this person lose any weight, but that doesn’t mean the calories don’t matter.
ConclusionWhat’s ultimately going on here? It’s clear that calories are the ultimate drivers of weight changes – even the supporters of the insulin hypothesis don’t argue that. But it’s also true that “eat less, move more” completely fails to capture the complexity of how calories are actually used in our bodies. And because we can’t actually control for all the aspects of the “calories in/calories out” equation, calorie restriction is not the best way to achieve long-term weight loss.
In other words, all three of these people are “right:”
Dr. Wayne Westcott, the fitness researcher associated with the Navy Seals, performed a study of different combinations of sets and reps in different styles of training, and came up with an unexpected number. All of the conventional styles of training that worked well for him seemed to end up at about a 70 second duration (+ or - 10 seconds). You could vary the number of reps and the speed of the reps any way you wanted to, as long as you ended up with an exercise that lasted about 70 seconds.
Is there a biological connection between anything that goes on in the muscles and 70 seconds?
Yes there is. Working at their peak level, intermediate twitch fibers exhaust in about 60 seconds, give or take 10 seconds, which leaves the last 10 seconds for the fast twitch fibers to exhaust.
Now here is the interesting common secret that you will get from almost every fitness guru.
"You have to push hard through those last 2 or 3 reps."
Why? Why wouldn't the first 60 seconds be enough?
Remember, INTENSITY of EFFORT is key! Why is so much determination necessary for the last 2 reps, and not for the first 60 seconds or so, with standard exercise? And why does all the new muscle mostly come as a result of the all out effort done right at the end?
A Little Light on Muscle Recruitment
The reason has to do with how the motor neurons that engage the muscle fibers are wired. They are wired in a fashion that requires you to fire all of the Slow Twitch Type I fibers before you fire the first Fast Twitch Type IIa fiber. And to fire all of the Fast Twitch Type IIa fibers before you fire the first Fast Twitch Type IIb fiber.
That type of biological techno-speak mumbo-jumbo is what used to get me picked on by the other kids in school, so let me give you an analogy.
You have rented out this theater to put on your daughter's play, and you want to shine a great spotlight on her during her big scene.
But the guy who does maintenance for the theater doesn't speak the same language that you do, and turns out to be really stingy with lighting. He has been instructed to keep the electric bill, and the bulb replacement bill as low as possible, but still make sure that you get all the lighting you need.
So he's installed a system where the bulbs are arranged in a row. The dimmest, longest-lasting bulb is the easiest to turn on, you just reach over and flick it on. He stuck that one closest to you because it's dim and has a ridiculously long lasting bulb. That way he saves on electricity, and you've got a bulb you can use all the time.
He shows the system to people, and shows them how he wants them to first turn on the 1st bulb, then the 2nd, and so on, so that they are always using the longest lasting lowest power bulbs for as long as possible.
But some people start cheating and just turn on the bulbs in the middle, to get bright light quickly. He doesn't like that because the middle bulbs don't last as long, and take more power. He'd rather you use two of the dim bulbs instead of one middle brighter bulb.
So what he stretches the bulbs out along a catwalk. Now you have to turn on the first bulb to be able to see your way to get to the second bulb, and you have to turn on the second bulb to get to the 3rd, brighter bulb. And this way he is certain that you only use as much electricity as you need, and you only use the longest lasting bulb that you can.
But just in case, there at the very end of the catwalk he's put some flash bulbs, just for the most brilliant light you might need (though they are the shortest lived)
Even so he has been instructed to make sure you have all the lighting you need, so if this ever isn't enough, he's to upgrade all of the lights to larger, brighter bulbs.
At first he would sit in the audience and watch the whole play just to make sure that you always had enough light.
Then he notices something. If you never turn on the flash bulb, then you always had enough light. Only if you turn on the flash bulb, only then do you need more light. And that's his way to be absolutely sure that the lighting needs to be upgraded. If you use the flash bulbs then, and only then does he know that the lighting needs to be upgraded.
Nature Is Efficient, Not Perfect
Your body is a lot like that theater manager. You can't tell it what you want, and it doesn't always use a clear signal to figure out what you want.
Conventional, 20th century fitness training with weights, somehow got locked into the notion that it isn't safe to do an all out effort, even though sprinters, shot putters and Olympic lifters routinely do exactly that.
And if you follow the analogy they are much like the father in the theater turning on everything except the spotlight on his daughter, and then only turning the spotlight on after the other lights burned out.
The theater manager didn't care if the other lights burned out or not, he was used to the way most people turn on the lights. Most people go straight out to that last light, turning every light on along the way, if they want more light than the theater has.
Who am I talking about when I say, most people? I'm talking about the entire animal kingdom, and all of humankind prior to the advent of weights.
Nature doesn't care about the dim lights in the Slow twitch fibers. Nature wants to know if you need the Bright lights, and especially if you burn out the brightest one in the house. Because if you do, an upgrade to the lighting is an absolute requirement.
The quickest way to burn out the bright one is to turn all of them on right away, including the bright one.
That's what sprinters do. That's what shot putter's do. That's what Olympic lifters do.
But don't do it with free weights, without a power rack. Unless you have the skills of an Olympic lifter and are prepared to just toss the weights to the side when you get in trouble, then it's just too dangerous.
And that, more than any other reason, is why the whole "wear out the weak lights before turning up the power" method of training has evolved, because of the unsafe nature of barbells that are near your strength limit.
But with a bar that doesn't move, that worry is a thing of the past.
Effort is the KEY!
The same way the theater manager could tell that you really needed newer brighter lights when you were willing to walk all the way out the catwalk, with all the lights on, your body can tell that you are serious only if you turn on every motor unit, which takes a massive amount of effort.
This amount of effort is foreign to most people. And there's a reason, because it is effort.
And it actually works both ways. The reason nature has made it so hard is that nature is stingy, and doesn't want to build any stronger a body than it has to. That strong body just takes too many calories to keep going. So nature made it as hard as possible to turn on the flash bulbs.
That's nature's way of knowing that you really needed the upgrade.
Your slow twitch fibers are nature's equivalent of 40 watt bulbs, and your fast twitch fibers are nature's equivalent of a flash bulb.
And the effort you have to put into it is nature's equivalent of the catwalk that the theater manager set up.
So if you think of the dim bulbs as the Slow Twitch Type I fibers, the brighter bulbs as the Intermediate Twitch Type IIa fibers, and the brilliant but short lived flash bulbs as the Fast Twitch Type IIb fibers, and you think of the light switches that all had to be turned on along the way as the motor units, then you have an image of the way muscle works.
So why 70 seconds?
If the weight used were so low that the slow twitch fibers could mostly handle it, then when the intermediate twitch fibers finally gave out the fast twitch fibers would only blow a few bulbs.
What's wrong with the analogy?
The analogy is not perfect. Your body does look down the row of lights a bit.
It does upgrade the lighting a little bit even if you never get to the last flash bulb.
But the evidence from shot putting, Olympic lifting, and 100 meter dash sprinting is very clear. In similar events, the shorter all-out effort grows faster larger muscles than longer efforts at lower intensities do.
Intensity, Muscle Size and Power
In the Olympics, which track athletes have the largest muscles?
Is it marathoners, who train by running up to 60 miles per week, then engage in an event that lasts about 2 to 3 hours?
Or is it sprinters, whose entire run lasts for about 10 seconds?
Compare a shot putter to a baseball pitcher? Who puts in more time? Who has the larger muscles?
The biological reason is that efforts that require a great amount of power require large muscles, whereas efforts that require a long effort only require a good blood supply and efficient energy system for a small muscle.
But here is the interesting point. In the sprinters, and in the shot putter's, even though their effort is all out, they are not exhausting the intermediate twitch, or the slow twitch fibers. And yet still their muscles grow larger then even the people who only exert slightly less power over only slightly longer times periods (400 meter people, javelin and discuss throwers)
If it took long duration efforts to produce muscle, or if duration (the extra time spent) helped build muscle, even a little, then the musculature distinctions between each higher distance, lower speed event would not be so clear.
At almost every increase in distance, and in time to the event, the average muscles size goes down.