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08/19/2020

Does eating late at night really make you fat? (chrono-nutrition)

Contents

  1. It's natural to gain weight by eating at night
  2. When late night eating habits lead to weight gain
  3. It's impossible to explain it with BMAL1
  4. Eating before going to bed does not cause weight gain

In Japan, many people (especially women) tend to avoid eating dinner, a dessert or sweets late at night (after 9 pm) because they do not want to "gain weight". But does it really make sense?

In fact, some people say that they have started eating dinner late at night and gained more weight than before, but I believe there is a false perception.

Summary

The phrase "gaining weight" has two meanings, and therefore there may be several patterns; surveys and studies based on only one viewpoint cannot capture the whole picture.

[related article]→2 meanings to the phrase "gaining weight"

(1) In a sense, everyone should be more likely to gain weight if they eat at night, since bones, muscles, and body fat are made mainly while they are sleeping. Especially people who usually take fewer calories to lose weight tend to gain weight when taking more calories than necessary. But in this case, it does not matter whether they eat at 7 pm or 10 pm.

(2) In terms of my intestinal starvation theory, late night eating habits can lead to increase in weight. Those people tend to skip breakfast and eat two meals a day. They may also find it difficult to eat a balanced meal late at night and the meal might be skewed towards carbohydrates, meat and junk food.
In other words, it is because eating late at night has a significant effect on "what to eat" and "meal intervals".

(3) It is impossible to correlate the secretion of BMAL1, a protein of the "clock gene" that promotes fat synthesis, with weight gain. It would be meaningless to compare the time of eating with the amount of secretion.

(4) For some thin people, eating a heavy meal before sleeping in addition to the three meals would rather work in the direction of losing weight. Energy is used more towards digestion, which should reduce the absorption of nutrients and synthesis of cells.

1. In a sense, it is natural to gain weight by eating at night

While we are sleeping at night, our bodies are not resting. They are doing something very important to our bodies while we are sleeping. I will not go into details here, but it is said that there are two main things:

One is the removal of waste products from the brain and the organization and consolidation of memory.

The other is body maintenance and cell regeneration. The secretion of "growth hormones" stimulates metabolism, repairs damaged cells throughout the body, recovers from fatigue, and improves the immune system. It is also said that various enzymes and tissues such as bones, muscles, and body fat are produced. 

Thus, in a sense, isn't it natural that eating late at night tend to make everyone gain weight? If you are on a diet regularly, you will realize that if you eat more calories than you need and go to bed, you will rebound a few kilograms per night. But that is when your present weight go back to your Base Weight (see Figure below), and in this case, it does not matter what time of night you eat.
  

2. When late night eating habits lead to weight gain

I sometimes hear people say "I did not gain weight when I ate dinner around 7 pm, but after working overtime and eating at 10 pm at night, I gradually gained weight. But that is a separate issue from [1] above, and is a case of Base Weight itself going up in my intestinal starvation theory.


First of all, many people tend to skip breakfast if they eat dinner late at night. This means they only have two meals, lunch and dinner. Also, getting home late at night and then finding a well-balanced meal can be difficult.

Unless their wife prepares a meal for them, they will end up eating ramen, curry, beef bowl, etc. which they get at a convenience store or at a restaurant that is open till late.

This means they will end up eating a high-calorie, nutritionally unbalanced meal.

In other words, eating dinner late has a great impact on "what to eat" and "meal intervals".
And in this case,
eating late is not a "cause" of weight gain. It’s a "consequence". The cause for this is an unbalanced diet skewed towards carbohydrates and meat(/fish), and putting up with hunger for hours by skipping breakfast, etc. 

▽One way to prevent this is to diversify meals, such as having a sandwich, cookies, or milk around 5 pm if dinner is going to be late. You should also try to eat a balanced diet.

3. It is impossible to explain it with BMAL1

Many Japanese experts confuse the two meanings of [1] and [2], stating as if secretion volume of BMAL1 and weight gain are correlated. 

BMAL1 is a protein of the "clock gene" that promotes fat synthesis, and its secretion increases around 6 pm and peaks between 10 pm and 2 am, which seems to be thought as a rational behind the fact that people are several times more likely to gain weight if they eat late at night than during the day for the same calories.

However, I think that explanation is a bit of a stretch. The reason is that the "digestion time" is missing.

For example, if they eat a meal at 10 pm, it will take 4-6 hours for it to be digested and absorbed, depending on the person.
Fats are particularly difficult to digest, so they may find that their stomach is still undigested and upset in the morning after 7-8 hours.


In other words, if it is not digested, it cannot be absorbed, so you cannot relate the time you eat it to your BMAL1 value.

In my guess, the reason why BMAL1 peaks between 10 pm and 2 am is that if we humans have been eating dinner around 6 pm since ancient times, it peaks at just about the time of finishing digestion and absorption (to be synthesized successfully).

4. Eating before going to bed does not cause weight gain

If they eat breakfast, lunch, and dinner properly, I think, for most people, eating before going to bed does not cause weight gain.

As I said earlier, if you eat a lot of calories than you need, you will definitely gain weight. It means your present weight goes back to your Base Weight. A weight gain might be 2 or 5 kilograms, depending on the person, but it should stop at a certain weight. 


In Japan, there are a lot of people who have gastroptosis or weak stomachs, and even if they eat a dessert, sweets or a light meal before bedtime in addition to the three meals to gain weight, their bodies might still work in the direction of slimming down rather than gaining weight (at least, it is true for me).

By nature, it is good to rest your body and your stomach while you sleep, but if you eat before going to bed, your stomach has to continue to work while you sleep. I believe that this reduces absorption capacity and cell regeneration.