Why "When to Eat" Is Important in Weight Management (The Concept of Chrono-Nutrition)


1. The current state of obesity in Japan
2. What is "chrono-nutrition?"
3. Researchers’ views and my argument
   (1) Skipping breakfast makes it easier to gain weight
   (2) Try to eat a balanced meal
   (3) It is difficult to gain weight from 6 am to 4 pm
4. My opinion toward the overall argument

In this article, I would like to introduce the basic concepts of a "biological clock" and "chrono-nutrition," and discuss the importance of eating breakfast in particular, with my thoughts on the subject. I will write about “late dinners” in another blog.

Long story short, I recognize the importance of "when to eat, what to eat, and how to eat," and I have no objection to the statement that eating a balanced breakfast is important not only for your health but also for prevention of weight gain.

However, I am uncomfortable with the use of "metabolism" as a catch-all term to explain whether you gain weight or not. Is “metabolism” such a panacea? I believe it should be better explained using my intestinal starvation theory.

1. The current state of obesity in Japan

"As of 2012, the number of diabetic patients in Japan is about eight-point-nine million (or twenty-two-point-one million including prediabetics). Diabetes started increasing in the 1970’s.

Then, you might think, “it is because Japan became rich and Japanese people started eating delicious food,” but the average daily energy intake dropped from twenty-two-hundred kcal (in 1970) to eighteen-hundred and fifty kcal (in 2010). 

Nevertheless, the number of diabetics has increased nine fold. Similarly, obesity has increased by forty percent among middle-aged and older adults between 1975 and 2010, even though the energy intake of Japanese people decreased by sixteen percent.

Today, people gain weight not because they eat much. Rather, they gain weight although they eat less."

(Reference: Yasuo Kagawa, Clock Gene Diet, 2012, Pages 14-16)

2. What is "chrono-nutrition?"

These below are just theories from the book listed above.

(1) Discovery of a "clock gene"

"Recent research has unraveled this mysterious phenomenon. It was a discovery of a clock gene of humans in 1997. Not only humans, but also all animals and plants have a “circadian rhythm” in which one day is twenty-five hours.

When we wake up in the morning and the sunlight (blue wavelength) is transmitted to the “central clock gene” in our brain, the twenty-five-hour circadian rhythm is reset to twenty-four hours and the day starts.

However, our internal organs do not receive the sunlight.
By eating breakfast, nutrients spread to every corner of the body, and they inform the “peripheral nerve gene” in each cell of the arrival of the morning, and that resets the twenty-five-hour circadian rhythm to twenty-four hours. 

(2) The effect of nutrients differs depending on when they are taken

In Japan, the term “chrono-nutrition” was used for the first time in 2008 by the Japan Society of Nutrition and Food Science. The more people try to lose weight, the harder they try to decrease the amount they eat from morning until night, but the effect and influence differ significantly depending on the time of day when food is consumed.

From early morning until about four p.m., the body is less likely to store body fat, and after nine p.m., calories are more likely to be stored as body fat.

It is said that the following three are important: ①When to eat (the timing of the meal), ②What to eat (dietary balance), and ③How to eat (the order of eating, the number of meals, etc.).

(3) What and how to eat

Eating vegetables first, followed by main dishes such as meat/fish, and then carbohydrates last, prevents a rapid rise in blood glucose levels, making the same menu less fattening.

Eating two meals a day, for example, is prone to storing fat in the body over time. It is better to divide it into multiple portions and eat one small portion at a time, even though it is the same total amount of food.

If you have to eat dinner late at night (e.g., at nine p.m.), it is better to divide your meal and eat carbohydrates by six p.m. and the other side dishes at nine p.m.."

(Reference: Yasuo Kagawa, Clock Gene Diet, 2012, Pages 16-24, 64-67)

3. Researchers’ views and my argument  (the relationship between breakfast and being overweight)

The following is a brief summary of the general theory of chrono-nutritionists in Japan. I will also show my rebuttal at the same time.

(1) Skipping breakfast makes it easier to gain weight

"Breakfast signals the "peripheral nerve genes" in each cell that the morning has come, resetting the biological clock. As a result, body temperature and metabolism rise, and the nutrients and calories taken at breakfast are burned off, so that even if you eat a lot, you are less likely to gain weight.

Moreover, the calories taken in at lunch are also used metabolically, and do not turn into body fat easily, even if you eat a hearty meal.

On the other hand, if breakfast is skipped, the metabolic rate remains low and the body is prone to weight gain.
A calorie-dense meal comes in all at once at noon, and it cannot be converted into energy rapidly, making it easier to accumulate body fat."

My argument

Aren’t nutritionists using metabolism as a magic word? It is true that breakfast will get the body's cells moving and increase body temperature and metabolism, but that is because the nutrition has been introduced. For a normal range of a meal, the increased metabolism should not exceed the calories consumed at breakfast. At the very least, the caloric surplus should be greater than for those who do not eat breakfast. 

Also, if you skip breakfast, your metabolism may remain low, but that's because your body is running on low fuel to reduce unnecessary energy expenditure, and if you eat lunch, I suspect your body temperature will likewise rise and your metabolism will increase within thirty minutes or so after you finish your meal.

Furthermore, even breakfast should be eaten when the metabolism is low after waking up from sleep. 

slim and fat

In other words, if we try to distinguish lean from overweight people by metabolism, all nutrients are absorbed equally by all, and the lean people burn more of them as energy.

Of course, metabolism may create some differences, but I don't think this is a sufficient explanation for weight gain.

(Some experts point out that skipping breakfast can lead to overeating at lunch and a rapid rise in blood sugar levels. That is another matter to be considered.)

(2) Try to eat a balanced meal

"An unbalanced breakfast (only bread and coffee or rice balls, etc.) resets the “peripheral nerve gene” halfway, so metabolism does not start properly and makes it easier to gain weight over time.

In an experiment to measure the calculating ability of children, it turned out an unbalanced breakfast such as only rice balls or bread and tea was almost the same as eating nothing. "

My argument

Of course, I admit that a balanced breakfast affects nervousness and concentration. However, even one slice of toast, ham and coffee increases your body temperature and provides energy for the brain. Then, how much metabolic difference is there between these two diets? 

In fact, some studies have reported that "glucose alone did not start the biological clock, but the combination of ‘glucose and protein’ started the biological clock the best," so I don’t think the explanation that an "unbalanced breakfast tends to make you fat since metabolism does not start properly" is sufficient.

Also, in the case of growing fruits or vegetables, isn’t it normal for them to grow bigger if you provide them with balanced nutrition? Even for human growth, it is essential to eat a nutritionally balanced meal.

Thus, the argument that eating a well-balanced breakfast increases metabolism and burns the extra calories you have ingested sounds strange. I think my theory better explains why an unbalanced diet makes people gain weight over time.

(3) It is difficult to gain weight from six a.m. to four p.m.

four p.m.

"The period from six a.m. to four p.m. is the time when the clock gene protein "BMAL1," which promotes fat synthesis, is not produced as much, so it is hard to gain weight even if you eat a calorie-dense meal or sweets."

My argument

I believe this contradicts what they mentioned earlier(1); "skipping breakfast keeps your metabolism low and eating calorie-dense food at noon makes you easy to accumulate body fat."

Of course, I understand that hormonal secretion, even with the same calories/nutrition, makes a difference in fat storage, bone formation, etc. between morning and night. But, after all, isn't it how you eat that matters, not determined by the time of day alone?

By the way, I would like to discuss "BMAL1" in more detail in another article about "late dinners."

[Related article]  Does Eating Late at Night Really Make You Fat?


4. My opinion toward the overall argument

While the idea that the reason for gaining weight is, “the total amount of caloric intake” is still pervasive, I think it is great progress that people came to understand “①When to eat, ②What to eat and ③How to eat” that affects the prevention of weight gain or losing weight.

Also, I have no doubt that breakfast and a well-balanced diet are important for concentration, weight management, and overall health.

Dinner time

However, the strange thing about this theory is that they are trying to explain everything that does not fit with the calorie theory, mostly by “metabolism.” Isn’t this a mere theory just linking “people who are slim though they eat a good breakfast and lunch” and “people who skip breakfast and tend to gain weight” to the values of metabolism? 

Moreover, as they say, “chrono-nutrition, if the relationship between the timing of the meal and nutrition determines whether or not people gain weight, then the explanation should only be "when to eat.” 

Nevertheless, they combined ②what to eat and ③how to eat, which sounds odd. As I mentioned at the beginning, my intestinal starvation theory should be more fitting. In the following blog, I will explain, “why eating a balanced breakfast leads to the prevention of weight gain” based on my theory.

[Related article]  The Reason Why a Well-Balanced Breakfast Helps Prevent Weight Gain