— Topics —


Can Thermodynamics Explain Why We Gain Weight?


  1. What does the first law of thermodynamics tell us?
  2. The human body is a mass of chemical reactions 
  3. Calories eaten is not the same as calories the body takes in. My thoughts
<The bottom line>

First, please read the following article. 
The Calorie Principle and Weight Gain; The Causality Has Been Obscure

According to Gary Taubes, it was first claimed in the early 1900’s by Carl von Noorden (a German diabetes specialist) that we gain weight because we take in more calories than we expend. This argument has continued to the present day, and we are told that taking in too many calories and lack of exercise are the causes of weight gain. 

This time, I would like to share the “law of thermodynamics,” which was said to be the basis for that theory. Mainly quoted from the book, it is so interesting that I think it is worth reading.

1. What does the first law of thermodynamics tell us?

"There are three laws of thermodynamics, but the one that the experts believe is determining why we get fat is the first one.

This is also known as the law of energy conservation: all it says is that energy is neither created nor destroyed but can only change from one form to another.

Blow up a stick of dynamite, for instance, and the potential energy contained in the chemical bonds of the nitroglycerin is transformed into heat and the kinetic energy of the explosion. 

Because all massour fat tissue, our muscles, our bones, our organs, a planet or star, Oprah Winfreyis composed of energy, another way to say this is that we can't make something out of nothing or nothing out of something.

This is so simple that the problem with how the experts interpret the law begins to become obvious.

All the first law says is that if something gets more or less massive, then more energy or less energy has to enter it than leave it.

It says nothing about why this happens. It says nothing about cause and effect. It doesn't tell us why anything happens; it only tells us what has to happen if that thing does happen. A logician would say that it contains no causal information.

packed place

Imagine that, instead of talking about why we get fat, we're talking about why a room gets crowded.

Now the energy we're discussing is contained in entire people rather than just their fat tissue.

Ten people contain so much energy, eleven people contain more, and so on. So what we want to know is why this room is crowded and so overstuffed with energy- that is, people.

If you asked me this question, and I said, Well, because more people entered the room than left it, you'd probably think I was being a wise guy or an idiot.
Of course more people entered than left, you'd say. That's obvious. But why? And, in fact, saying that a room gets crowded because more people are entering than leaving it is redundant-saying the same thing in two different ways-and so meaningless.

Now, borrowing the logic of the conventional wisdom of obesity, I want to clarify this point.
So I say, Listen, those rooms that have more people enter them than leave them will become more crowded. There's no getting around the laws of thermodynamics.

You'd still say, Yes, but so what? Or at least I hope you would, because I still haven't given you any causal information. This is what happens when thermodynamics is used to conclude that overeating makes us fat.

eating snack

The National Institutes of Health says on its website, “Obesity occurs when a person consumes more calories from food than he or she burns.”

By using the word “occurs,” the NIH experts are not actually saying that overeating is the cause, only a necessary condition. 

They're being technically correct, but now it's up to us to say, Okay, so what? Aren't you going to tell us why obesity occurs, rather than tell us what else happens when it does occur? "

(Gary Taubes, Why We Get Fat, 2010, Pages 73-75 )

2. The human body is a mass of chemical reactions 

"The first law states that energy can neither be created nor destroyed. In other words, energy can be converted from one form to another, but the total amount of energy in the universe remains constant. How might this law apply to weight management?

Suppose someone has stable weight over time. The first law dictates that, in theory, the number of calories consumed by this individual in the form of food is equal to the calories the individual expends during metabolism and activity. In other words, 'calories in = calories out’.(*snip*)

However, the first law of thermodynamics actually refers to what are known as ‘closed systems' -ones that can exchange heat and energy with their surroundings, but not matter. Is this true for human beings? 

chemical reaction

Actually, no: the human body does indeed exchange matter with its surroundings, principally in the form of the food (matter in) and as waste products such as urine and faeces (matter out). 

Also, technically speaking, the first law refers to systems in which chemical reactions do not take place.

But the human body is essentially a mass of chemical reactions. So, here again, the first law of thermodynamics cannot apply where weight management is concerned.

(Dr.Jone Briffa,Escape the Diet Trap, 2012, pages 63,64  )

3. Calories eaten is not the same as calories the body takes in. My thoughts

Two authors have made excellent points about the relationship between thermodynamics and weight management. Based on those thoughts, I would also like to mention two points about the relationship between thermodynamics and my theory.

(1)What constitutes "caloric intake" 

I also basically believe that if a person has a stable weight over the years, then "the energy consumed  and the energy expended for basal metabolism and activity,etc." must be balanced.
The question, however, is: at what point have we "taken in" energy? 

If we calculate calories at the point we put food in our mouths and consider it "calories consumed," then it is no wonder that for many people it is not balanced with the energy expended.

This is because, as Dr. Briffa pointed out, our bodies are not "closed systems.” If we consider energy absorbed from the gut to be "calories ingested," then it should be considered more of a "closed system."

▽Let's take the example of calcium in milk.

From experience, we know that it is not always true that the more milk we drink, the more calcium we take in and the stronger our bones will become.

Just because a bedridden old lady drinks five glasses of milk a day every two hours every day, does not make her bones stronger; in fact, it sometimes has the opposite effect. Even with just a glass or two of milk a day, exercising more and feeling hungry can increase absorption rate and make her bones stronger. 

In other words, it is not the amount of calcium drunk, but how much calcium is absorbed through the intestines that is balanced against the amount of calcium used in the body(some of the calcium in the blood can be excreted as urine). 

As Dr. Briffa pointed out, our bodies are "a mass of chemical reactions," so what is not absorbed ends up outside the body in the form of fecal matter. 

(2) When energy intake increases

Based on my intestinal starvation mechanism concept, even if a person who has maintained the same weight over the years, significantly reduces their usual caloric intake (e.g., about two thousand kcal daily) and the intake of carbohydrates, but meets the "three factors + one" criteria as I mentioned in another post, they will gain weight (this means an increase in base weight).

[Related article] →Three (+one) Factors to Accelerate “Intestinal Starvation”

Of course, weight gain mostly occurs when the person then goes back to the original diet, but in this case, absorption ability itself goes up, meaning that not only body fat, but also blood and muscle mass,etc. increase, resulting in "weight gain."

In short, even though you are eating the same amount of food (calories) as before, you are taking in more energy and nutrients into your body than before, which means you are getting bigger/fatter.
In the words of Gary Taubes, "a room crowded with ten people now has eleven people," and in this case,
it is “intestinal starvation” that has caused it.

The bottom line

(1) Experts believe that the cause of obesity is the "imbalance between caloric intake and consumption" based on the "law of energy conservation" (the first law of thermodynamics).

(2)Since the human body is a mass of chemical reactions and not a "closed system," it does not make sense to compare the total calories actually eaten with the calories expended. In this case, the "law of thermodynamics" does not hold.

(3) If we base it on the calories actually absorbed in the intestines, it should be closer to a "closed system" and be balanced with the calories expended through one’s basal metabolism and activity,etc.

(4) If intestinal starvation is induced and your base weight goes up, you will gain weight even if you are eating the same amount as before, which means that the energy taken into the body has increased. Since the absorption ability itself has gone up, the increase in body weight is related to not only body fat, but also blood and muscle mass,etc.


The Calorie Principle and Weight Gain; The Causality Has Been Obscure


  1. The birth of the "calories-in/calories-out" theory 
  2. Obesity is still on the rise
  3. Carl von Noorden's book

In Japan, most people believe that “taking in too many calories and lack of exercise are the causes of being overweight,” which I believe is largely due to statements made by experts, nutritionists, etc. on television.

When I launched this website in 2014, I wanted to argue against that in my website, but I couldn’t find any academic papers and other resources that showed the "causal relationship between caloric intake and becoming obese." 

However, around a year after I started blogging, I came across this great book: “Why We Get Fat” written by Gary Taubes. It is surprising that it was published in Japanese in 2013.

After all, this is the only book I can rely on. In explaining what I want to say, I first needed to let you know that, "the direct cause of being overweight is not determined by overeating.”

1. The birth of the "calories-in/calories-out" theory 

"Ever since the early 1900s, when the German diabetes specialist Carl von Noorden first argued that we get fat because we take in more calories than we expend, experts and non-experts alike have insisted that the laws of thermodynamics somehow dictate this to be true.

Arguing to the contrary, that we might actually get fatter for reasons other than the twin sins of overeating and sedentary behavior, or that we might lose fat without consciously eating less and/or exercising more, has invariably been treated as quackery "emotional and groundless," as the Columbia University physician John Taggart insisted in the 1950s in his introduction to a symposium on obesity.

“We have implicit faith in the validity of the first law of thermodynamics," he added.

Such faith is not misplaced. But that does not mean that the laws of thermodynamics have anything more to say about getting fat than any other law of physics.

Newton's laws of motion, Einstein's relativity, the electrostatic laws, quantum mechanics -they all describe properties of the universe we no longer question.
But they don't tell us why we get fat. They say nothing about it, and this is true of the laws of thermodynamics as well.

It is astounding how much bad science-and so bad advice, and a growing obesity problem-has been the result of the experts' failure to understand this one simple fact. The very notion that we get fat because we consume more calories than we expend would not exist without the misapplied belief that the laws of thermodynamics make it true. (*snip*)

The physicians of Bruch's(German pediatrician that moved to America in 1934) era weren't thoughtless, and the doctors of today are not, either.
They merely have a flawed belief system-a paradigm-that stipulates that the reason we get fat is clear and incontrovertible, as is the cure.

We get fat, our physicians tell us, because we eat too much and/or move too little, and so the cure is to do the opposite. (*snip*)

This is what Bruch described in 1957 as the “prevalent American attitude that the problem (of obesity) is simply one of eating more than the body needs,” and now it's the prevalent attitude worldwide.

We can call this the “calories-in/calories-out” or the “overeating” paradigm of excess fat—the “energy balance” paradigm, if we want to get technical.

“The fundamental cause of obesity and overweight," as the World Health Organization says, “is an energy imbalance between calories consumed on one hand, and calories expended on the other hand." 

We get fat when we take in more energy than we expend (a positive energy balance, in the scientific terminology), and we get lean when we expend more than we take in (a negative energy balance).

Food is energy, and we measure that energy in the form of calories. So, if we take in more calories than we expend, we get fatter. If we take in fewer calories, we get leaner.

This way of thinking about our weight is so compelling and so pervasive that it is virtually impossible nowadays not to believe it.

Even if we have plenty of evidence to the contraryno matter how much of our lives we've spent consciously trying to eat less and exercise more without success— it's more likely that we'll question our own judgment and our own willpower than we will this notion that our adiposity is determined by how many calories we consume and expend. "

(Gary Taubes, Why We Get Fat, 2010, Pages 7,8,73)

2. Obesity is still on the rise

"Consider the obesity epidemic. Here we are as a population getting fatter and fatter.

Fifty years ago, one in every eight or nine Americans would have been officially considered obese, and today it's one in every three. Two in three are now considered overweight, which means they’re carrying around more weight than the public-health authorities deem to be healthy.

Throughout the decades of this obesity epidemic, the calories-in/calories-out, energy-balance notion has held sway, and so the health officials assume that either we're not paying attention to what they've been telling us -eat less and exercise more-or we just can't help ourselves.

Malcolm Gladwell discussed this paradox in The New Yorker in 1998.
“We have been told that we must not take in more calories than we burn, that we cannot lose weight if we don't exercise consistently," he wrote.
“That few of us are able to actually follow this advice is either our fault or the fault of the advice. Medical orthodoxy, naturally, tends toward the former position. Diet books tend toward the latter. Given how often the medical orthodoxy has been wrong in the past, that position is not, on its face, irrational. It's worth finding out whether it is true.”


(Gary Taubes’s thoughts on the relationship between thermodynamics and weight gain)

Obesity is not a disorder of energy balance or calories-in/ calories-out or overeating, and thermodynamics has nothing to do with it. If we can't understand this, we'll keep falling back into the conventional thinking about why we get fat, and that's precisely the trap, the century-old quagmire, that we're trying to avoid."

(Gary Taubes, Why We Get Fat, 2010, Pages 7,8,73)

3. Carl von Noorden's book

Japanese television programs still continue to show doctors and nutritionists confidently saying, "The cause of weight gain is, of course, overeating or lack of exercise,”which I find disgusting. However, I hope you can see how flimsy and baseless these theories are.

By the way, I obtained Carl von Noorden's book (archive), which is shown at the beginning of the quotation. You can read it at the following link: 

 Carl von Noorden's book



Calculating Daily Caloric Intake; Three Reasons Why Diets Don't Work


  1. The human body is not that simple
  2. Why a simple daily caloric intake calculation is meaningless

1.The human body is not that simple

Here, I want to show you that “comparing the daily intake of calories with the average amount of calories burned to calculate how many calories you stored as fat, or how much fat you lost,” doesn't really have a meaning.

According to Dietary Guidelines for Japanese, the recommended daily caloric intake is 2,000 calories (kcal) a day for women, and 2,500 for men. Off course, an ideal daily intake of calories varies depending on factors such as age, size, height and levels of physical activity.
And it is said that you’ll gain weight if you take in more calories than your body needs and that you’ll lose weight if you use more energy than you consume.

Based on this idea, often on television in Japan, a nutritionist or a doctor says to those who gained weight, “You have 120kcal over the line per day meaning 3,600kcal per month. This is equivalent to 0.5kg body fat. So, if you keep on like this for four months, you will accumulate two kilograms of body fat.” (Based on a calculation of one kilogram of body fat =7200kcal).

Is that true?

Calculating the daily caloric intake is useful as a rough standard of average necessary energy for cooking on a large scale, such as in a school or a retirement home.

However, it is meaningless to use it as a standard for individuals, and for a sense of being overweight, that’s another problem.

2.Why a simple daily caloric intake calculation is meaningless

 Though there might be several reasons, I would like to explain the following three as my own reasons.

(1)  It's the intestinal starvation mechanism that causes your base weight value to go up

Please read this first. →  Two Meanings to the Phrase "Gaining Weight"

I’ve already explained that there are two meanings when you find yourself gaining weight.
With regard to (A) in the graph below, it is meaningless to calculate the daily caloric intake and talk about how much weight you gained.
This is based on the intestinal starvation mechanism, and an absolute amount of calories you eat won’t directly cause a change.

So here, I will explain how meaningful or meaningless it is to precisely calculate calories you ate, and talk about how much weight you can lose with regard to the range of (B) in the graph in the following sections, (2) and (3).

As you can see, it's a temporary way of reducing your weight. It won't solve the actual cause of the weight problem.

(2) There is no meaning in comparing a calorie label on food products with burned calories

This message, “you’ll gain weight if you take in more calories than your body needs” is very simple, and in a way, it sounds like getting straight to the point. That’s why many people believe in it and never doubt it.

However, this message is really vague, so I think it’s crucial to understand the difference between “the calories that your body needs” and “the calories you take in.” 

Not only in calories but in all nutrition, our bodies can’t digest and absorb everything we eat, and the absorption ability differs with each person.
Also, a calorie label on food products is calculated based on “combustion heat,” but the actual reaction in our body is chemical (thermogenesis). So, there is little meaning to calculate displayed calories or a nutrition index.

Burnd calories and absorbed one

What needs to be compared here is “the internal intake amount” which means the absorbed amount in the intestines.

I have to say that people who don’t lose weight easily even though they have reduced caloric intake are absorbing more calories than displayed calories they ate, and those who never gain weight even though they eat a lot are absorbing fewer calories than displayed calories.

It’s not that thin people have good metabolism (reference #1), but they have a limit due to their absorption ability.

In Japan, people sometimes say, “It’s inefficient that you eat a lot but can’t gain weight” but it really is the truth. It’s inefficient. If you try to compensate for this through intake volume, the absorption rate will decrease relatively, so it just won’t work (refer to #3).

On the other hand, there is an expression, “You have a body that gets fat by only drinking water.” It indicates those who gain weight easily even though they eat very little.

Of course, “water” is an exaggeration, but it’s true that their tendency to get fat is really that high. This is another example that expresses the absorption ability.

(3)Absorption ability is not fixed but increases from hunger or exercise

People who want to lose weight try to precisely calculate calories they eat and control their weight. Of course, their desired weight will decrease to some extent, but they’ll find themselves not losing weight faster than they expected.

When we are feeling being hungry for some time or after doing sports, our absorption ability ーwhich means absorption rate and absorption amountー increases and when we eat even though we are not feeling hungry, the absorption ability decreases.

The intestines do not absorb food at the same pace, but they control the absorption ability in order to maintain the body’s present condition. It’s much in the same way as the body temperature is always around 98.6℉(or 36℃). (Also, it has been proved through experiments that the less caloric intake there is, there is less basal metabolic expenditure).

(Japanese traditional breakfast)

For example, even if you skip lunch and eat nothing until dinner, there is still breakfast in your intestines. Your intestines are working really hard to take nutrition out of what is left. If there is no nutrition anymore in the intestines, the body will break down protein or body fat temporarily.

However, the more hunger continues, the higher the absorption ability after dinner is (and the body fat that was used up previously will recover soon).

That is to say, the body is working in a sense to maintain constancy of that person. So, even if you calculate your reduced calories every day, the body fat won’t decrease at the same pace.


If we change our meals from steak and bread/rolls (about 850kcal) to a hot dog (about 450kcal), the difference by a simple calculation is minus 400kcal.
But it’s only the number and even if you total them for a month, there is no meaning in it. Rather, there might be the intestinal starvation occurring between lunch and dinner that is causing your base weight value to go up.

▽ Let’s look at another example of a thin person who wants to gain weight and therefore eats a lot.
If he/she eats a meal every four to five hours even though they are not feeling very hungry, their absorption rate will decrease relatively. (Of course, it differs in each person).

Consider this, after we eat food, it digests for three to four hours, and finally, when it is starting to be absorbed, more food comes into the stomach. So, the body will perceive that “here comes some more food... we can simply absorb it.”

That explains the old Japanese saying “being hungry is the best nutrition.” What increases the absorption ability are hunger and exercise (especially weight training).

<reference 1>

October 2016, Professor Osumi’s “Autophagy”(taken from the Greek meaning “cell’s self-eating mechanism”) won the Nobel Prize in Physiology and Medicine.

It clarified, in the case when there is no nutrition in the cell as such as in long starvation, how unnecessary protein is broken down into amino-acids and reused as a nutrition source.

That is to say, there is no waste in the human body as it will recycle even unnecessary protein. Logically saying, “Thin people have a good metabolism” is a ridiculous idea that neglects the mystery of the human body.