“We get hungry, and if we can’t satisfy that hunger, we’ll get lethargic and our metabolism will slow down to balance our intake. This happens whether we’re lean or obese, and it confounds those authorities who recommend exercise and calorie restriction for weight loss. They operate under the assumption that the only adjustment to the calorie deficit created by either dieting or exercising will be a unilateral reduction in fat tissue This would be convenient, but the evidence argues otherwise.”
Gary Taubes, Good Calories, Bad Calories
“Although humans can modulate food intake by voluntary control in the short term, the almost invariable weight regain that occurs in obese persons after weight loss suggests that in the long term, biologically determined feelings of hunger and satiety may be more important than voluntary control of food intake” (1).
I have been spending some time going back through old textbooks to review metabolism and homeostatic processes in the human body. Today, while reading through the chapter on homeostatic control in my Neuroscience textbook, I found myself thinking about calorie balance.
You may be wondering how neuroscience led to thoughts on calorie balance. Well, I was reading about how the brain and body work together to maintain homeostasis, the scientific term for an organism’s ability to maintain equilibrium using physiological processes. For example, the behavioral processes the body uses to keep the body energized and functioning well involve behaviors such as eating and drinking, along with movement. To produce these behaviors and maintain a steady balance, the body has an intricate balance of neural and endocrine (hormonal) systems in place.
As my eyes read over page after page describing these complex mechanisms, with explanations of all the hormones, enzymes, neural pathways involved, I just couldn’t help but think how utterly absurd it is that people could advocate for a theory in which all the complex processes could just be thrown out the window and replaced with the simple concept: “Just eat less and exercise more.”
When it comes to discussing the power of the human mind, not many people get as excited as much as I do. Yet, when it comes down to comprehending the extent of the role that our conscious minds have, our overemphasis on this superpower often goes too far, even as far as to lead down the path to our demise.
What makes us humans so special may be our ability to make conscious decisions, yet this very statement can result in an overemphasis on how powerful the cerebral cortex, particularly the frontal cortex, really is.
So here I am, reading through these textbooks on neuroscience and biology – reading up on all these endocrine and neurological processes, along with how they respond to signals from the body and produce behaviors. Remember, this is all accomplished to maintain homeostasis and a well-functioning body. Curiously though, reading through these pages and pages describing energy store regulation, nowhere did I see a thing about how all these metabolic processes can just be overridden by the frontal cortex (our brain’s conscious decision-making center). There were pages on different hormones and how they dictate hunger, along with the question of whether to store or burn the body’s fuel sources. There were pages on how these all interact with certain centers in the brain, causing behaviors such as eating or movement. However, there was not a single sentence on how all this is irrelevant, because we can just override it all with our wonderful frontal cortex.
Now, this makes sense to any scientist that knows anything about biology. Biology is extremely complex, and the fact that, out of all these sophisticated processes we get functioning organisms, is incredibly remarkable. The sophisticated nature of homeostasis is well-known in the scientific world. In this world, complexity is a given, and scientists spend their time digging into the depths of this complexity to iron out the details. But unfortunately, this understanding of complexity is lost once we move over into the real world.
Because in the real world, science doesn’t rule the world. People, with their oh-so-special frontal cortexes, get to make decisions – and these decisions don’t often make sense when merged with scientific facts. What emerges is advice that is unaligned with the scientific facts and data.
This leads us to the topic that could very well have the most significant impact on most individuals – calorie balance theory.
Just a heads up as to what this will involve – I will dive into some of the useful information from the textbook later on, which will involve getting into some of the major metabolic pathways that are responsible for maintaining homeostasis (e.g. body weight). Once we have an understanding of how our bodies actually work, then we can develop methods to manage weight that are aligned with the laws of nature, and don’t outright go against it. And yes, we’ll get into how the idea that we can just overrule all of it with conscious control is absurd.
But, before that, we have to first understand the calorie balance theory so that we understand its limitations. I’m sure you are familiar with the concept on some level, as the term “calories” is plastered everywhere in the modern world, and calorie balance is the common practice used by most doctors, nutritionists, and other health officials that you go to for help to lose weight. However, not many individuals understand what the theory actually is at its core, and this understanding is necessary given the willingness for this society to so fully embrace the theory.
Calorie balance:
In case you are unfamiliar with the model, here’s how it looks:
calories in – calories out = change in energy stored
This model is an extension of the first law of thermodynamics, which has been simplified to the statement: energy can neither be created nor destroyed; therefore any difference in calories consumed and calories expended results in a change in weight.
This then gets translated to the advice that to lose weight, one must create a calorie deficit. This can be done by either eating less, and/or exercising more. Should be simple, right? Just eat less, exercise more, and voila, goodbye fat rolls.
But, of course, if it were that easy, 70% of this country wouldn’t be overweight, and I wouldn’t be writing this post.
To figure out why it doesn’t work, let’s look more closely at the model. The first law of thermodynamics holds true – after all, it is a fundamental law of nature. It is correct to state that energy can’t be created nor destroyed, which means that energy that goes into the body must be accounted for by energy expended or energy stored. Thus:
calories in – calories out = change in energy stored
However, the problem is that this gets translated to:
calories eaten – calories expended = change in body weight
This interpretation means that a calorie surplus causes weight gain, while a calorie deficit causes weight loss.
And at last, here we have the problem. First, it is important to recognize that this is an equation. There is an equals sign in the middle, not an arrow. That means that this model can be driven either way. Yes, it could occur that the difference in food intake and calories expended causes a weight change. But it also could happen such that weight change causes a change in food intake or calories expended.
Let’s discuss that, because it sounds funky on the surface, but it actually does happen. The classic example is puberty, when the body starts going through lots of changes, including putting on some extra weight (especially for women). And of course, that infamous teenage appetite comes right along with it. Now, puberty doesn’t occur because kids eat so much. Rather, the kids are eating so much because their bodies are growing.
One very relevant case in my own life is the following. Have you ever eaten a large meal, and afterward been completely compelled to move. This is a normal phenomenon in runners like myself, who get the feeling that they just have to move. – it seriously feels like I’m going to burst if I don’t get up and get moving around. This is a case where caloric intake drives the need to burn calories, because the body is programmed to maintain the same body weight. The body is sending the signal that you need to move, which it does both consciously (the desire to work out), but also unconsciously (resisting the urge to move results in movement such as pacing, twitching, etc.)
Unfortunately, this doesn’t happen for everyone, because not everyone is programmed the same way. Fortunately, our brain and bodies are incredibly malleable and can be reprogrammed to want to move, rather than the strong desire to remain sedentary found in most people today. We’ll get into this programming in the next article.
To strengthen this point, let’s examine how the scientific literature differs from the calorie balance common wisdom.
One of the most often cited cases of metabolic control is ob/ob mice. These mice lack the Ob gene that allows for the production of a key controller of hunger – leptin. These leptin-lacking mice are incapable of controlling their hunger and naturally grow obese. Similarly, mice that lack the gene for the receptor of leptin (db/db) also can’t control their hunger and grow obese. These mice show us how a disruption in hunger signaling, either by a lack of messenger or receptor for the signal to stop eating, causes someone to eat and eat and eat.
Note the subtle driving force here – these rats don’t keep eating because of a conscious desire to eat more food which would result in a change in their body. Rather, the disrupted signal in their body drives them to put on weight, making them eat.
Gary Taubes, in his book Good Calories Bad Calories, discusses several cases of specific rat studies that defy the calorie balance model. One of the most well-known cases of the insignificance of calories and weight loss are Zucker rats, which are defined by a specific genotype that causes them to put on fat at a much faster rate than normal mice, even when calories are restricted. Just the simple fact of the existence of these rats is in direct opposition to the concept that weight loss is about controlling our calorie intake and expenditure. These Zucker rats demonstrate how changing an internal factor (e.g. a gene), rats that eat the same amount as normal mice, or even Zucker rats forced to eat less than normal rats, still gain more fat.
The evidence goes even further than demonstrating the irrelevance of calorie balance theory, demonstrating how this practice of calorie restriction can even be dangerous. Taubes uses a specific example of a study by Jean Mayer in the 1950’s, which demonstrated that rats that were starved were still able to put on fat. These rats actually sacrificed their muscle and tissues to put on fat intake, rather than lose the fat tissue that doctors and nutritionists say will disappear, if only we could eat fewer calories. We can go back even further to 1936, when Francis Benedict examined a strain of obese mice, which were restricted from food, and found they “lost 60 percent of body fat before they died of starvation, but still had five times as much body fat as lean mice that were allowed to eat as much as they desired.” These rats died with five times the fat still on their bodies!
Taubes explores these ideas in great depth with many more examples, so if you want to learn more check out his book.
I will note one particularly interesting study from the book – a group of rats that had their ovaries removed, which, as Taubes explains, ate “voraciosuly,” were less physically active, and grew obese. This in itself shows that just by disrupting certain hormones produced in the ovaries, the eating behavior changed, resulting in obesity. But it gets more interesting. In a group of ovary-lacking rats with calories set at the level they were at before the surgery, the rats grew just as obese. This study shows that when specific hormone production is destroyed (ovary removal), rats grow obese, regardless of the amount eaten. They could be fed a normal amount, or excess, and they still put on the same amount of weight! This shows us that hormones, not calories, are dictating the weight gain.
Okay, so now we see that calorie restriction and weight loss aren’t so straightforward – what about the addition of calories to lose weight? Is it possible to eat more and lose weight, something that completely undermines calorie balance. A number of studies exist pointing to the addition of calories resulting in either no significant weight change, or even weight loss. A 2007 review examined several such studies and found a large number of isocaloric randomized control trials in which the addition of different nuts did not result in any weight gain. This means that, in two groups eating the same base diet with the same amount of calories, one group fed extra calories from different nuts did not gain any weight. Even more impressive are the studies this paper (again, isocaloric, randomized control studies) in which the addition of either almonds, pecans, or walnuts led to a decrease in weight. Again, these studies do not support the hypothesis that to lose weight we should eat less. Clearly, there is more at work here than simple calorie counting.
Remember, when we lose weight due solely to a caloric deficit, the body often compensates by increasing appetite and decreasing energy expenditure. This is documented time and time again in the literature, such that it is a given in research articles that have appeared in the past decade (1-3).
If you still aren’t convinced, here’s one more case for you. Sylvia Tara, PhD, in her book The Secret Life of Fat, documents many such calorie-restricted diets. In one interesting study, she explains how “…they compared the food intake of twenty-six obese patients before and after they lost an average of 115 pounds. Although this was a significant amount of weight, these patients were still overweight and were termed ‘reduced-obese.’ This group required 28 percent fewer calories to maintain their reduced weight… when the scientists compared the food intake of the reduced-obese to that of control subjects who were never obese to begin with… the reduced obese were eating slightly fewer calories than the never-obese group, but their weight was still 60 percent higher.”
Again, we see the calorie balance model falling apart. These people are eating less, 28 percent less, and yet weigh 60 percent more. Conventional wisdom would tell them that, well, they just need to move more, and keep eating less. If that’s the best medical advice we have, it’s pathetic.
And once again, we get the same insight: simply restricting calories not only fails to reach the goal of getting rid of fat, but it actually makes the problem worse in the long run. After going through this calorie restriction cycle, these people now eat fewer calories, yet still weigh more than others. Their body has been programmed to be great at holding on to energy. At this point, conventional wisdom would just tell their poor, starving bodies to eat less, which would only serve to drive the deeper into starvation mode.
For now, I hope to provide just enough evidence here to get you thinking that this whole calorie balance weight loss plan might be a load of B.S. In my next article I’ll dive into how the weight is actually managed by the body, including the major biochemical and neurological pathways involved. For now, I’ll leave you with this: next time you think it is necessary to starve yourself to lose weight, think about these mice, starving, while their muscles and tissues wither away, and their fat deposits remain in place. There has to be a better way.
To work towards an understanding of a more effective solution, let us think about the entire picture. First, we have this concept of calorie balance. We know that the first law of thermodynamics holds true – after all, it is a fundamental law of nature. So why then is it such a failure when put into practice as a method for weight loss. If it’s true that, to lose weight, we need to eat less and burn more, why does focusing on these two things not only fail, but often backfire?
I want to leave you with my thoughts on the two main reasons why this model fails. It comes down to the calorie balance model being an oversimplification of all the processes occurring in the body. Calories are not the only factor involved in weight management, and to be honest, when it comes to what is driving mass balance in the body, calories have a very insignificant role.
In addition to the fact that calorie balance is an oversimplification which ignores relevant metabolic processes, the use of the model itself comes with a misinterpreted of the theory on which it is based. This is to say that, while energy balance does hold true for any closed system, it is not true that it implies any sort of causality when it comes to the ultimate effect of restricting energy into a system.
Out of this comes two key ideas as to why calorie balance as a weight loss practice fails regularly:
1. Calorie balance puts too much emphasis on conscious control, and it de-emphasizes the metabolic processes the body uses to maintain homeostasis. When this fails, the person gets blamed (not the method, or the ones prescribing it).
2. It sends the wrong signals to the body. Instead of reprogramming the body for weight loss, it often keeps programming it for more weight gain.
To lose weight, we need to be able to control hunger while keeping the body active. Clearly, calorie balance does not help with this. But, calorie balance theory has one more attempt – telling those that are overweight that they just need to try harder – that it is their gluttony and sloth that are making them fail. From what we have already discussed, it doesn’t make much sense. But, from the health advice perspective, it makes a lot of sense to tell you to just overpower those annoying metabolic processes fighting to make you fatter.
But now we know that this doesn’t work. All those cases I discussed, along with all our own trials, make one thing very clear. Willpower is really quite weak. Sure, it can be employed occasionally to fight off that chocolate cake or a second serving. But, at the end of the day, when your body thinks it’s starving, it is going to find the calories it thinks it needs. Unless you have iron hard willpower, or are somehow physically restrained from food, your body will find that energy that it wants. And if it doesn’t get it, your entire body is going to suffer – muscles, brain, and all.
And that’s only your physical body – not only are you left with excess weight that you try so hard to lose, you are also left with feelings of guilt and shame because, once again, you lost control.
Let me make this clear – the idea that we have conscious control over our metabolic processes is flawed. If you look at the scientific literature on weight loss, one thing is very clear. Again, the knowledge that calorie restriction leads to increased hunger and decreased energy expenditure is a given. This knowledge comes from decades of studies, like the ones above, that show that weight is regulated by an intricate balance of hormones and neurological processes – NOT your frontal cortex. Assuming that our conscious control reigns supremely over our metabolic processes is plain ignorance, and those health experts that continue to use this method are being lazy and irresponsible.
If you want more insight into how our brains and bodies actually work, check out my next article on how weight is controlled by the body, where I dig into metabolic control, from both a neurological and physiological perspective.
So where does this leave us? If calorie balance plainly doesn’t work, and likely causes more harm than good, what could we possibly do to lose weight?
Overall, we need a new model – one in which calories are not ignored, but they are used as a piece of a much bigger puzzle, and are certainly not the centerpiece. To build this model, we need to have a general idea of the most important metabolic processes. Once we understand these, we can understand what and how to eat to optimize our fuel burning capacity.
Journal References:
1.Chearskul, S., Delbridge, E., Shulkes, A., Proietto, J., & Kriketos, A. (2008). Effect of weight loss and ketosis on postprandial cholecystokinin and free fatty acid concentrations 1 – 3, 1238–1246.
2. Brain Res . 2010 September 2; 1350: 95–102. doi:10.1016/j.brainres.2010.05.062
3. Rosenbaum, M., Sy, M., Pavlovich, K., Leibel, R. L., & Hirsch, J. (2008). Leptin reverses weight loss – induced changes in regional neural activity responses to visual food stimuli, 118(7), 2583–2591. http://doi.org/10.1172/JCI35055.relevant
Book References:
1. Taubes, Gary. Good Calories, Bad Calories. Anchor Books, 2008.
2. Tar, Sylvia. The Secret Life of Fat. New York: W.W. Norton & Company, Inc., 2017.