Many experts still believe that “one calorie is one calorie.” If we apply this idea to weight control, we have to only be concerned with the number of calories in our diet, regardless of what different foods we eat or how we eat them. Of course, the human body is not that simple, and many researchers have warned against this kind of thinking.

In explaining this, I thought I should make a distinction between reactions that occur "inside" the body (after absorption) and those that occur “outside" the body (before absorption) (Note 1).
In this article, I would like to consider the Atwater coefficient, which is the basis for calorie labels on food products, as an issue that occurs outside the body. 

Atwater set up an experiment using a “bomb calorimeter” to measure the caloric content in food. Foods with evaporated water were placed in a highly pressurised sealed container surrounded by a certain amount of water. The container was filled with pure oxygen to burn the food. The caloric content in the food was then calculated from the rise in temperature of the surrounding water. The amount of energy required to raise the temperature of one liter of water by one degree Celsius at sea level is defined as one kilo calorie[2].

However, digestion is a series of gentle chemical reactions over many hours, not like burning food in a bomb calorimeter. Therefore, we can only extract a certain percentage of calories in  food. So, it is said that Atwater fed human volunteers a variety of foods and measured the heat of combustion of the resulting fecal matter. By calculating the difference in heat of combustion between the food and the feces, he was able to approximate the number of calories absorbed by the volunteers. 

Atwater also took into account the fiber in food which we can’t digest(Note 2), and the nitrogen in our urine extracted from protein and excreted as urea. More than one-hundred-twenty years after this experiment, these "Atwater coefficient" are still the basis for caloric calculations for all foods[3].

(Note 2: It is now known that dietary fiber produces some energy through fermentation and breakdown by  the bacteria in the large intestine[4].)

We ingest food and then break down complex food molecules into simple structures such as glucose and amino acids by various digestive enzymes. After that, we get an energy source by absorbing them. Naturally, this is a completely different process compared to burning food in the laboratory. 

According to Professor Rob Dunn (North Carolina State University), every calorie count on food labels is based on estimates or approximations, and are not an accurate reflection.

Recent research has revealed that how many calories we get from a given food depends on a variety of factors, including which species we eat, how we cook food, which bacteria are in our gut, and how much energy we use to digest different foods (diet-induced heat production).
   

A study by Janet A. Novotny at the U.S. Department of Agriculture (2012) found that when people eat almonds, they take in just 129 kcal per serving, not the 170 kcal listed on the label. It is beginning to be proven that nuts such as peanuts, almonds, and walnuts have a more robust cellular structure than other foods with similar levels of energy sources, and that their cell walls limit digestion[8]. It is possible that the Atwater coefficient overestimates the digestibility of nuts.
    

Furthermore, some have pointed out that industrial food processing not only exposes food to high temperatures and pressures, but also softens food by adding air, to make it even easier to get more calories.

Corn, for instance, which is considered indigestible, is made into potage, and raw peanuts are roasted and processed into peanut butter. These processes must have dramatically increased the amount of energy available to the body. In other words, not all pork dishes are the same. The energy used for digestion and the absorption rate differ when roasting a chunk of pork versus making it into pâté.
   

Some research has shown that the energy required for digestion is not the same. This is called “diet-induced thermogenesis,” and it requires a great deal of energy to convert proteins into amino acids, fats into fatty acids, and carbohydrates into glucose. It is said that when proteins are broken down into amino acids, they require as much as five times more energy to digest as fats, because enzymes must unravel their tightly wound bonds[10].

According to Prof. Rob Dunn, it also differs between whole grains and refined wheat. In a 2010 study, they found that people who ate 600-or 800-kcal portions of whole-wheat bread with sunflower seeds, kernels of grain, and cheddar cheese expended twice as much energy to digest that food as those who ate the same amount of white bread and "processed cheese products.” Consequently, those who ate whole-wheat substantially obtained ten percent fewer calories, they said[11].

Most babies have lactase, an enzyme necessary to break down lactose sugar in milk, but it is said that most adults don’t produce this enzyme.

It has also been found that when starches such as rice and spaghetti are left to cool after being cooked, some of these starches crystallize into structures that digestive enzymes cannot easily break down.

What’s more, some microbes are present only in specific ethnic groups. Some Japanese, for example, have a microbe in their intestines which is suitable for breaking down seaweed. It has been found that these intestinal bacterium stole the seaweed-digesting genes from a marine bacterium that lingered in raw seaweed [13].
    

The general Atwater coefficients were calculated based on the average daily diet of Americans at the time. Digestibility for carbohydrates, fats, and proteins were assumed to be 97, 95, and 92 percent respectively, and after adjusting a little for this, protein and carbohydrates were set at 4 kcal/g, fats at 9 kcal/g, and alcohol at 7 kcal/g[14]. Although metabolizable energy values vary slightly for proteins, depending on whether they are vegetable or animal protein, and for carbohydrates, depending on whether they are sugar or starch, the coefficients were derived by a system of an average.

On the other hand, specific Atwater coefficients are also allowed, which divides food into several groups and applies that thinking to the entire group.

It is said that the U.S. Food and Drug Administration (FDA) allows a total of five variations on the theme including these, and some point out that depending on the method chosen by the food company, there may be variation on the calorie labels[15]. When such uncertainties add up, the daily caloric intake could vary widely.
    

Prof. Rob Dunn mentions as follow:

(1) It is possible to modify the Atwater system for every food group, as in the almond example. However, this would require a challenge to reexamine the amount of nutrients retained in the feces for every food. 

(2) However, even if we completely revised calorie counts, they would never be accurate because how many calories we extract from food depends on a complex interaction between food, the human body, and its many microbes. In particular, the process of digestion is so complex that it is probably impossible to derive an accurate formula for calorie calculation that will suit everyone.

(3) Instead, we should think more carefully about the energy we get from food in the context of human biology. Processed foods are easily digested in the stomach and intestines, and thus provide a lot of energy for very little work. On the other hand, vegetables, nuts, and whole grains require more sweat to digest, offer far more vitamins and nutrients than processed foods, and keep our gut bacteria happy[16].

I believe that researchers and nutritionists at that time, including Atwater, were committed to ensuring that people could have an adequate amount of nutrition, and the calorie counting system they created had great merit. But I suspect it has been misperceived by some and is now causing problems with those who are overweight.

The reason why the problem of obesity hasn’t been solved is that many people are so focused on the "number of calories ingested or burned" that they are likely to forget what is most important.

▽Let's say you eat, as in the example in the section 2-[III], 400 kcal of a meal, whole-wheat bread, nuts, and grilled chicken. Assuming that, after taking into account the energy required for digestion, you obtained ten percent fewer calories (360 kcal), the argument that "wouldn't it be the same if you ate 360 kcal worth of white bread and chicken terrine?" is complete nonsense.

Similarly, conventional advice and actions often taken to reduce daily caloric intake, such as skipping breakfast or eating a light lunch such as a hamburger or a cup of noodles, can also cause intestinal starvation and lead to increased base weight.

I have been explaining throughout this blog that the fundamental difference between obese people and thin people can be explained by the difference in base weight value, and that a higher base weight means "higher absorption ability," which is induced by intestinal starvation. And since one of the key factors causing intestinal starvation is how fast you digest food, both digestion and absorption ability are extremely important in my theory.

Nevertheless, if we believe that only numbers based on averages of subjects are all we have, we ignore them. As Rob Dunn mentions, I don’t believe that the complexity of digestion and absorption for a diverse population can be described by a system using an average.

(Please read the following article for other issues in "calorie counting.")

There is No Meaning in Simply Calculating Calories You Consume

The Atwater coefficients is a measure of how much energy we can obtain from food, but I think it is inadequate to address the problem of obesity. Even if we revised the Atwater coefficients more accurately by taking into account energy required for digestion and food composition, the obesity problem will not be solved if we judge things only by the number of calories.

One idea that has been suggested is to introduce a "traffic-light" system on food labels, alerting consumers to foods that are highly processed (red dots), lightly processed (green dots) or in-between (yellow dots) [17], and I agree with this idea. It is also possible to combine satiety, the number of chews, and the indigestibility of food into this traffic-light system.

References：
[1](Cynthia Graber, Nicola Twilley, “Why the calorie is broken”, BBC future, 2016) 
[2][3](Giles Yeo, "Calories on food packets are wrong–it's time to change that",2021) 
[4](Japan Food Research Laboratories, “The Energy in Food”「食品のエネルギーについて」,2003) 
[5](The Nutrition Coordinating Center (NCC),"Primary Energy Sources")
[6](Kazuko Takada, “Absorption and Utilization of Energy in the Body”, Physical Fitness Science , 2007, P56, 287-290)
[7][8][9][10][11][12][13][16](Rob Dunn,"Science Reveals Why Calorie Counts Are All Wrong", 2013)
[14](Kazuko Takada, “Absorption and Utilization of Energy in the Body”, Physical Fitness Science ,2007, P.56, 288)
[15](Cynthia Graber, Nicola Twilley, “Why the calorie is broken”, BBC future, 2016) 
[17](Richard Wrangham, Rachel Carmody, Harvard University,”Why Most Calorie Counts Are Wrong”, 2015)

The Atkins diet is a type of low-carbohydrate diet proposed by cardiologist Robert Atkins that restricts the amount of carbohydrates for energy and instead uses "fat" as an energy source. It is characterized by limiting carbohydrates to twenty to twenty-five grams per day for the first two weeks and then gradually increasing.

According to Dr. Fung, the author of “The Obesity Code,” Dr. Atkins weighed nearly one-hundred kilogram in 1963, and when he began working as a cardiologist in New York City, he needed to lose weight. 

However, he couldn’t lose weight successfully on a conventional calorie-restricted diet, so he tried the low-carb diet based on the medical literature which worked well as advertised, and he recommended it to his patients. 

In 2004, twenty-six million Americans said they were on some kind of low-carb diet .
In the mid-2000’s, new studies began to compare the Atkins diet to other diets that were once considered the standard, and what were the results?[1]

Let's take a look. I would like to express my thoughts on this at the end of this article. 

"In 2007, the Journal of the American Medical Association published a more detailed study: Four different popular weight plans were compared in a head-to-head trial.

One clear winner emerged-the Atkins diet. The other three diets (Ornish, which has very low fat: the Zone, which balances protein, carbohydrates and fat in a 30:40:20 ratio; and a standard low-fat diet) were fairly similar with regard to weight loss. 

While the Mediterranean diet held its own against the powerful, fat-reducing Atkins diet, the low-fat AHA standard was left choking in the dust–sad, tired and unloved, except by academic physicians.[2]" 

"Longer-term studies of the Atkins diet failed to confirm the much hoped-for benefits.
Dr. Gary Foster from Temple University published two-year results showing that both the low-fat and the Atkins groups had lost but then regained weight at virtually the same rate. (*snip*) 

A systematic review of all the dietary trials showed that much of the benefits of a low-carbohydrate approach evaporated after one year.

These foods are clearly fattening, no matter what diet you believe in. We continue to eat them simply because they are indulgent. (*snip*)The Atkins diet does not allow for this simple fact, and that doomed it to failure.

The first-hand experience of many people confirmed that the Atkins diet was not a lasting one. Millions of people abandoned the Atkins approach, and the New Diet Revolution faded into just another dietary fad. (The company Dr. Atkins founded in 1989 went bankrupt.)

But why? What happened?
One of the founding principles of the low-carbohydrate approach is that dietary carbohydrates increase blood sugars the most. High blood sugars lead to high insulin. High insulin is the key driver of obesity. Those facts seem reasonable enough. What was wrong?[3]"

Experts who advocate low-carbohydrate diets seem to think that carbohydrates cause weight gain because they eventually stimulate insulin secretion.

However, Dr. Fung mentioned that the hypothesis is incomplete. Various problems are cited, but he raised the "paradox of the Asian rice eater" and the "diet of Kitava Island, in Papua New Guinea" as notable examples.  

Most Asians have been eating a diet based on refined rice as their staple food for at least the last five decades; a study conducted in the late 1990’s found that carbohydrate intake in China and Japan was similar to or rather, higher than in the U.K. and the U.S. 

▽Since Dr. Fung just mentioned the paradox of the Asian rice eater, I would like to mention this.

I am Japanese and was born in 1970, and I think that I should know how our diet has changed in the last five decades, and as a result, how obesity has increased in our society. 
(This is explained in more detail in the following blog.)

[Related article]  Why Does the Body Perceive That It Is More Starved than in the Past?

In short, I believe that carbohydrates are a contributing cause, but not the quantity itself.
Japan was basically an agrarian society, and rice cultivation has always been important. Japanese people have always eaten a lot of rice as it is called the "main” food, but at the same time, they also ate a lot of fibrous vegetable dishes using roots or stems of plants, fermented soybean product called “natto,” and fish and meat dishes. Rice cakes called “mochi” and Japanese sweets as well.

At least in my family, my father was strict about family members eating meals three times a day at a regular time, every day.
  

I believe that the "three factors plus one" of my intestinal starvation theory can explain how the various factors intertwine, and how weight gain occurs. It's not just the amount of carbs eaten that matter.

The "Do calories make people fat, or carbs?" concept is said to be a debate that has been going on since the 1800’s [5], and I think both are true in some ways, but neither is perfect.

If you reduce the amount of any energy source beyond what your body needs, it’s obvious that you will lose weight in the short term.
However, if you go back to your original diet, in the long run, you will also regain the weight you had lost, as various studies have confirmed, and as most people who have been on a diet have probably realized.

The reason for this is that the human body, I believe, basically works to maintain the status quo. I introduced "base weight" to describe the body weight based on that. So, the point is that in order to avoid rebounding, you must lower your base weight itself. 
(For more information on how to do this, please see the following article.)

[Related article]  There Are Two Steps to Lose Weight the Right Way

In terms of this rebound in the Atkins diet in section three, I don't think it necessarily means that low-carb diets, including Atkins, are ineffective. I’m positive that it’s the one of the correct ways to lose weight.

However, if we focus too much on blood sugar and insulin levels, we lose sight of another important point.

What I mean is that, the point of a low-carb diet, I believe, is not only the reduced carbohydrate amount, but also "how we increase the amount of other indigestible foods including meat, fat/oil, fibrous vegetables, dairy products, etc."
By sending plenty of indigestible foods to the gastrointestinal tract, we should feel less hunger and, in turn, the absorption rate should decrease. In particular, fats and oils must be consumed every meal and even when having snacks.

From that point of view, I think that dieticians did not need to ban sweets such as chocolate, candy, ice cream, etc. so strictly. What is important is to be able to have them occasionally and not be too hard on yourself.

<Reference>
[1] (Dr. Jason Fung, The Obesity Code, 2016, Page 96-99)   
[2][3] (Page 100-103)
[4] (Page 103-105)
[5] Gary Taubes, Why We Get Fat, 2011, Page148-162)

(1) In the early 2000’s, the Atkins diet became a huge trend in the U.S., following the resurgence of the low-carb boom from the 1990’s. In the short term, the Atkins method not only helped people lose weight, but it also significantly improved blood pressure, cholesterol, and blood glucose levels.

(2) However, in long-term studies, the subjects rebounded, as seen with low-fat diets. After one year from the end of the study, all the benefits of Atkins diets were gone.
Dr. Fung considered the "carbohydrate-insulin hypothesis" an incomplete theory. Carbohydrate intake itself was not the problem.

(3) My thoughts. If there is no change in your base weight, rebound can occur if you eat as you used to. In order to lose weight correctly, your base weight itself needs to be lowered.

(4) The point of a low-carbohydrate diet is not just "insulin." I believe that it’s rather important to "take in more indigestible foods other than carbohydrates and not feel hungry." 

In Japan, the image of sumo wrestlers in particular may lead to the image that "eating more makes you fat," but I would like to explain that this is the same mechanism as "those who end up rebounding after dieting and gain more weight than before" or "those who gradually gain weight by skipping breakfast or having a late dinner.”

First of all, I'm going to illustrate how both of them gain weight in the figure below. 
  

When you see big eaters in a food eating competition, some may ask, "Why don't they get fat even though they eat so much?” But, from my theory, it is not at all surprising.

It’s not that they have a special "non-fattening constitution," but that anyone who eats like that from morning to night is less likely to gain weight (although I wonder why they can eat so much food at once).

Please understand that the way of eating of a sumo wrestler is a far cry from that of an eating competitor.
   

(1)A wrestler must weigh at least sixty-seven kilograms to be admitted. People who are overweight or muscular from the beginning tend to have stronger stomachs, and are thought to have a relatively high digestive rate. Such people are more likely to induce gut starvation than thin people.

(4)They traditionally eat two meals a day: the first meal is around eleven a.m. after morning practice, and dinner is around six p.m.
Since they practice from the early morning without breakfast, if dinner is finished at seven p.m., it means that they do not eat for about fifteen to sixteen hours until the next meal. It make sense to do intense morning training on an empty stomach to gain weight.

Of course, there are some wrestlers who try to eat snacks or supplements late at night in order to take in more calories, but my idea is that it makes easier to gain weight when they don't eat.

(1)Sumo wrestlers are famous for being big and fat, but they do not gain weight because their daily caloric intake exceeds their daily caloric expenditure.
Their traditional diet and exercise makes sense in terms of weight gain in that it facilitates the creation of intestinal starvation.

(2)Intestinal starvation is more likely to be induced when a person who has a big body from the start eats relatively easily digestible foods with lots of carbohydrates (rice) and two meals a day.

(3)The mechanism by which wrestlers gain weight is the same as that of "people who diet and gain more weight than before due to the rebound effect.”
In the case of sumo wrestlers, since they eat a lot every day, this happens almost simultaneously, and they appear to eat a lot and gain weight.
    

According to a survey, more than fifty percent of Japanese people put on some weight during the period of staying at home by government order to prevent the spread of the coronavirus.

I think two classic examples of "eating a lot or stopping exercising makes you fat" fit here.
Normally, these people were under the strain of their jobs, moving all day long, eating in moderation, and paying attention to caloric intake. If that tension is gone and they simply exercise less and eat more, they will naturally gain weight.

Sometimes I hear people say, "I ate too much at the all-you-can-eat buffet yesterday and gained three kilograms in one night.” They may have simply gained body fat or the weight of the food in their gut may also be a factor.

But It is a big mistake to say, "Okay, let's skip today's lunch." 

With the recent gourmet food boom, many delicious foods are introduced on television and social media, while many people are worried about gaining weight and are trying to eat less.

If you skip meals or eat light meals (e.g. hamburgers and coffee) to reduce calorie and carbohydrate intake, you will deal with hunger for a longer period of time.

Even if you lose a little weight temporarily, the lack of fats, oils, dairy products, and fibrous vegetables can lead to intestinal starvation and an increase in your base weight over the long haul.

Unknowingly, your base weight may go up, and one day, when you eat like you used to, you may find that you have reached your highest weight ever. And it will be harder to lose weight than before.

The first step in becoming leaner is to eat three well-balanced meals religiously every day. 
Even if you want to reduce total caloric and carbohydrate intake, be sure to consume fiber-rich vegetables, seaweed, dairy products, proteins such as meat and fish, and oils every meal.

(1) Some people claim to have gained a few kilos during the Covid self-quarantine period, but I believe most cases can be explained by a return to one’s base weight as well as a rebound effect.

(2) The idea of adjusting for yesterday's excess calories by eating fewer calories today is a mistake when it comes to maintaining a stable weight in the long run.

(3) People who usually eat less and hold back on the foods they want to eat for dieting, and occasionally splurge on treats, are more likely to gain weight over the long haul.

Irregular eating, where a person eats on and off, can cause intestinal starvation when a person is dealing with hunger over many hours, unknowingly increasing their base weight.

(4) Since the gastrointestinal tract basically begins with breakfast and the food we eat reaches the rectum in around twenty hours or so, it is important to eat three well-balanced meals every day if you do not want to gain weight.

"Obese children often have obese siblings. Obese children become obese adults. Obese adults go on to have obese children. Childhood obesity is associated with a 200 percent to 400 percent increased risk of adult obesity. This is an undeniable fact. (*snip*)

Families share genetic characteristics that may lead to obesity. However, obesity has become rampant only since the 1970s. Our genes could not have changed within such a short time. Genetics can explain much of the inter-individual risk of obesity, but not why entire populations become obese.

Nonetheless, families live in the same environment, eat similar foods at similar times and have similar attitudes. Families often share cars, live in the same physical space and will be exposed to the same chemicals that may cause obesity–so-called chemical obesogens.
For these reasons, many consider the current environment the major cause of obesity.(*snip*)

The classic method for determining the relative impact of genetic versus environmental factors is to study adoptive families, thereby removing genetics from the equation.(*snip*)

Dr. Albert J. Stunkard performed some of the classic genetic studies of obesity. Data about biological parents is often incomplete, confidential and not easily accessible by researchers. Fortunately, Denmark has maintained a relatively complete registry of adoptions, with information on both sets of parents.

Comparing adoptees to their biological parents yielded a considerably different result. Here there was a strong, consistent correlation between their weights.

The biological parents had very little or nothing to do with raising these children, or teaching them nutritional values or attitudes toward exercise. Yet the tendency toward obesity followed them like ducklings. When you took a child away from obese parents and placed them into a "thin" household, the child still became obese.(*snip*)

This finding was a considerable shock. Standard calorie-based theories blame environmental factors and human behaviors for obesity. Environmental cues such as dietary habits, fast food, junk food, candy intake, lack of exercise, number of cars, and lack of playgrounds and organized sports are believed crucial in the development of obesity. But they play virtually no role.

Studying identical twins raised apart is another classic strategy to distinguish environmental and genetic factors. Identical twins share identical genetic material, and fraternal twins share 25 percent of their genes. 

In 1991, Dr. Stunkard examined sets of fraternal and identical twins in both conditions of being reared apart and reared together. Comparison of their weights would determine the effect of the different environments.

The results sent a shockwave through the obesity-research community. Approximately 70 percent of the variance in obesity is familial.(*snip*)

I think this is a very interesting study because it compared data from biological parents and adoptive parents.

However, can we assert from the results of this one alone that the influence of genetics was much greater and environmental factors were much less significant?

I believe, as Dr. Fung mentions, the rapid increase in obesity in recent years (since about 1970) has much to do with changes in our living environment (what we eat, irregular lifestyle,etc.),not the genes.

The study considers a child living with adoptive parents or twins raised separately to be a "change in living environment," but I think there is a problem with this study.

If a family can afford to take in a child as adoptive parents, don't they have some money to spare and feed their adoptee a somewhat balanced diet three times a day?
Although what they eat and caloric intake may differ from family to family, those changes don’t necessarily lead to a change in what I call their base weight. Just because the adoptive parents are thin does not mean that adoptees will become thin even if they eat the same diet.

For example, there is a Japanese comedian who is very fat (she always laughs off her being fat). She didn't know breakfast existed until she was thirteen years old (because her mother never made it at all), but what if such a family were her adoptive parents?
If a child is adopted into such an extreme family, it may well affect their weight in the long run, but if they are in a family that feeds them a standard diet three times a day, It can’t be said that it is a "change in environment."

In Japan in the past few decades, our traditional habits have been declining. Instead, our diet has become more westernized and our ways of working have become more diverse.
When some of these conditions such as not eating breakfast or lunch, eating late at night, fast food, not eating vegetables, carbohydrate-dense food, etc. are combined, intestinal starvation may be induced and lead to an increase in base weight.

This is the "environmental factors and human behaviors for recent obesity epidemic,” I want to say, and I believe that environmental factors has more influence than genetics. (Of course, genetic factors cannot be ignored).

But, I’m simply wondering what the childhood body shape is due to? Whether it is genetic factors or the way food is fed during childhood－including weaning－is a question that remains unanswered.
   

(1) In a study regarding adoptive families and examining how genetic and environmental factors influence being overweight, no correlation was found between the weight of adoptive parents and that of their adoptees.
On the other hand, when the adoptees were compared to their biological parents, there was a consistent correlation between the weight of both.

A study of twins raised separately also concluded that "genetic influences are far more significant.”

(2) Many researchers had previously blamed "environmental factors and individual behavior” for the recent obesity epidemic, but this study concluded that genetics had far more impact than environmental factors.

However, I find this study problematic. The fact of children living with adoptive parents or twins raised separately is not necessary an environmental factor that causes changes in weight.

(3) Regarding the similarity in body shape between biological parents and their children, of course, I do not think we can ignore the genetic factor, but the recent obesity epidemic can be explained by my intestinal starvation theory.

A major change in weight and body shape occurs when one’s base weight value goes up, which is induced by intestinal starvation. It requires (three + one) factors for that to occur.

(4) If there is no significant change in base weight, I think the body shape from childhood is expected to continue. However, I 'm uncertain what determines childhood body shape, whether it is heredity or the way food is prepared during childhood, including weaning.