The Reason Why a Well-Balanced Breakfast Helps Prevent Weight Gain


  1. "Metabolism" has become a magic word
  2. How eating breakfast affects weight management? My thoughts
  (1) A well-balanced breakfast can help prevent gaining weight
  (2) Lightening your breakfast and lunch makes you more likely to gain weight
  (3) Skipping breakfast makes it easier to gain weight
    The bottom line

In the previous article, I introduced the concepts of a "biological clock," and “chrono-nutrition,” but if you have not read them yet, please read the following article first.
This time, I am going to state my own thoughts on how eating breakfast affects weight management concretely by my intestinal starvation theory. 

[Related article]  Why "When to Eat?" Is Important in Weight Management

1. “Metabolism” has become a magic word

In Japan, it is often said that lean people who eat a lot but do not gain weight have a fast metabolism. On the other hand, those who tend to gain weight are often told that they have a slow metabolism. The word “metabolism” has been used like a magic word. 

The same idea goes for breakfast. Eating breakfast will raise body temperature and metabolism, and the extra calories from breakfast and lunch will be burned off, so it is thought that people won’t gain weight even if they eat a lot. Many researchers and experts use metabolism as a silver bullet or a cure-all to solve obesity, but I beg to differ. It has already been proven that people who are overweight have a faster basal metabolism.[1]

2. How eating breakfast affects weight management? My thoughts

I think the concept of “chrono-nutrition” is very important in this day and age, but there are many aspects that cannot be explained by metabolism or hormones alone. I believe, as I have mentioned in previous articles, that it makes more sense to explain this with my intestinal starvation theory.

(1) A well-balanced breakfast can help prevent gaining weight

Breakfast is the start of the day, and when you eat breakfast, your resting gastrointestinal tract becomes active.

If you eat a variety of food at that breakfast, such as dairy products, fibrous vegetables, seaweed, legumes, and fish or meat products, you can prevent intestinal starvation because undigested food will remain in your intestines for around ten hours or so (this is because our intestines are seven to eight meters long). 

Three balanced meals a day

Also, if you eat well both at lunch and dinner, you are less likely to gain weight, since there is some undigested food remaining over a twenty-four-hour period in your gastrointestinal tract  (it means that your base weight does not go up).

(Typical Japanese breakfast we used to have)

This is the reason why people who are already overweight cannot necessarily lose weight when they eat breakfast, but those who are originally slim or medium-sized and have this kind of lifestyle are unlikely to change their body shape throughout their lives, even if they eat without worrying about calories.

In other words, "when you eat, what you eat, and how you eat" affects weight gain/loss because they are closely related to the movement of the intestines.

(2) Lightening your breakfast and lunch makes you more likely to gain weight

On the other hand, breakfast can be fattening (in the sense that it increases one's base weight) even if one eats it. It is a so-called inverted triangle-type diet, in which breakfast and lunch are light (one might even skip lunch) and dinner makes up for the missing nutrients and calories.

light breakfast and lunch

For example, if you just have a light breakfast (a piece of bread, coffee and ham) in the morning, and a rice ball, hamburger, or instant noodles, etc. for lunch, it is easy to induce a intestinal starvation state before dinner, contrary to the situation described in (1) above.

When the gastrointestinal tract becomes active after breakfast, you usually defecate, and when you do, the only food left in your stomach is what was eaten at breakfast (in this case, mainly carbohydrates and easily digestible protein). 

If lunch is also a simple carbohydrate-based meal and lacks fiber and other nutrients, all the food in the intestines will be digested by dinner, which makes it easier to develop a state of intestinal starvation. 

In short, if breakfast is well-balanced from various food groups, you are less likely to gain weight, but if it is a simple and unbalanced one, there is good chance you will gain weight over the long haul. 

Some chrono-nutritionists say that “an unbalanced breakfast makes the body clock reset halfway, and your metabolism remains slow” but other research has shown that the combination of “glucose and protein”-food that raises insulin levels-is best for starting the body clock,[2] so in this case, I think the explanation "you gain weight easily since your metabolism doesn't start properly,” does not apply.

(3) Skipping breakfast makes it easier to gain weight

Skipping breakfast does not make everyone fat, but I think, if some conditions are met and overlapped, it makes you more likely to gain weight.

The biggest issue is simply a matter of "what to eat" at lunch and dinner and the interval between meals. Eating only two meals a day makes the meal intervals longer. If you finish dinner at nine p.m., you will not eat for almost fifteen hours until the next day, at noon.

Skipping breakfast makes you hungry, so in Japan, people tend to eat a carbohydrate (rice or noodles)-and-meat-focused meal. Some of them are satisfied with just being full, and their meal may lack fiber and other nutrients.

hearty meal at lunch

However, since they have not eaten breakfast, all they have in their gut is that meal at lunch.

If they don’t eat until eight or nine p.m. in that state, they are likely to induce intestinal starvation (a state where everything is digested) and their base weight may go up in the long run.

Some experts also point out that skipping breakfast and eating a carbohydrate-dense meal when hungry can cause blood glucose levels to spike, leading to high insulin secretion. This may be true, but in any case, this type of eating habit is the worst.

You can prevent intestinal starvation by doing the following: If you don't have time to eat in the morning, at least drink some milk, or eat a balanced lunch with a smaller amount of carbohydrates. And if you have to eat late dinner, eat something such as milk, chocolate or nuts, even around five p.m.

Dr. Jason Fung, The Obesity Code, 2016, Page 62.
[2] Akiko Kotani(古谷彰子), Chrono-Nutrition Reveals the Rules for Eating (時間栄養学が明らかにした食べ方の法則), 2014, Pages 97-98.

The bottom line

(1) Breakfast is the start of the day, and a well-balanced breakfast prevents intestinal starvation by allowing undigested food in the gastrointestinal tract to remain around ten hours. If you eat three balanced meals a day, some undigested food will stay in your stomach all day long, and your base weight will be less likely to go up. If a person who is originally slim or medium-sized continues such habits, they are likely to maintain the same body shape, but if a person is already overweight, eating breakfast does not necessarily mean that they will lose weight (since their base weight is already high).

(2) If breakfast is skipped and meals are eaten twice a day (lunch and dinner), the interval between meals will be longer, which can easily cause intestinal starvation, depending on what you eat. Eating a carbohydrate-rich meal at noon when you are starving is also bad for your health in terms of raising blood glucose to somewhat unhealthy levels.

(3) Even if you eat breakfast, if your breakfast and lunch are simple and unbalanced, you are more likely to induce intestinal starvation before dinner. This kind of eating habit may increase your weight in the long run, even if the amount of food eaten is small.

(4) The reason why "when you eat, what you eat, and how you eat" affects weight management is because it closely ties into the movement of the intestines. The influence of hormones, of course, cannot be ignored, but it feels odd to explain it simply by giving the excuse of, ”It’s your metabolism.”