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.