A Low-Carb Diet:Is Lowering Insulin Secretion the Key to This Diet?


  1. What’s Locabo?
  2. Sugar Busters
  3. Indirect significance of reducing carbohydrates. My thoughts
    The bottom line

In Japan, since around 2015, the low-carb diet-we call "Locabo" based on the English term "a low-carb"-has been catching on among many people. Japan is traditionally a rice-eating culture, but after World War II, more and more people preferred bread and noodles, and with increasingly westernized diets, many feel that we are gaining weight as well. 

This time, I’d like to introduce the Locabo diet in Japan and Sugar Busters in the U.S., which is believed to be effective not only for losing weight but also for lowering abnormal blood sugar levels and other lifestyle diseases.

At the end of this article, I'd like to weigh in on this. To get straight to the point, the right way of losing weight, my thinking is closer to that of a Locabo and a Sugar Busters diet, but I’m wondering if the hormone insulin is the key to these diets.

1.What’s Locabo?

"In Japan, the phrase “carbohydrate restriction diet” has been generally used, but the word “restriction” has a somewhat negative image.

Therefore, we had to use some different words. We came up with the new word “Locabo” after the English phrase “low-carb” and then it spread throughout Japan. 

Locabo is not strict but rather a loose carbohydrate restriction.
By definition, the diet tries to keep the carbohydrate intake amount per day to around seventy to one hundred and thirty grams in total, by taking twenty to forty grams per meal, three times a day and also a dessert or sweets up to ten grams. 

The difference from a strict carbohydrate restriction is that by eating at least seventy grams of carbohydrates, it avoids an extremely low-carbohydrate condition that results in “Ketosis.”

Also, a strict carbohydrate restriction diet makes food choices very limited, but Locabo has a variety of foods you can enjoy.
As long as you keep adjusting carbohydrate intake, you can eat a variety of foods such as meat, fish, cheese, and vegetable dishes without thinking about calories."

<Old history of low carbohydrate diets>

In Japan, when the Locabo diet first garnered attention around 2015, people thought it was a new dieting method. However, it seems to be a way that has been repeatedly conducted around the world since the 1800’s. I’ll explain this in the link below.

 Do Carbohydrates Make Us Fat or Do Too Many Calories?: The debate since the 1800's

2. Sugar Busters

I’d like to introduce “Sugar Busters,” which was a trend since the late 1990’s, especially in the U.S. (New Orleans) and was called the “food revolution.” 

Those who advocated the Sugar Busters diet said that the point of Sugar Busters was to regulate the secretion of insulin. They also said that insulin control depends on restricting carbohydrate intake. 

fish dish

In other words, as long as you restricted carbohydrate(sugar) intake, you could enjoy steak, grilled fish, cheese, etc. without thinking about calories. 

It is said that restaurants in the town created the Sugar Busters menu and this made the movement even stronger. It’s surprising that this was done more than fifteen years before the rise of the low-carb trend in Japan.[2]

3. Indirect significance of reducing carbohydrates. My thoughts

The way of losing weight on these low-carb diets is close to my idea, but from the perspective of my theory, the implications are a little different. Allow me to explain.

I feel that carbohydrates are treated as culprits that make people fat in this diet method because they stimulate insulin secretion. I agree that abnormal blood glucose levels are associated with various diseases and that carbohydrates are a major contributing factor that make people fat.

However, I would like to believe that insulin secretion, even though it promotes fat storage, does not create the fundamental difference between people who are obese, and lean people.

As I have mentioned many times in this blog, the root cause of being overweight, in my opinion, is an “increased base weight,” which is caused by intestinal starvation. And this is more likely to occur with digestible carbohydrates and protein, even in small amounts, combined with an unbalanced diet.

Such a diet, for sure, tends to raise blood sugar and stimulate insulin secretion, but it is a different mechanism that increases base weight value and makes people fat, and regarding my theory, insulin  doesn't have much to do with it.

What does have an effect, then, is the "dilution effect" or "push-out effect" that carbohydrates (polysaccharides) have. That, in combination with other factors, indirectly makes people more likely to induce intestinal starvation. (It’s “indirectly” that matters).

[Related article]
The Dilution Effect/ Pushing Out Effect of Carbohydrates

On the other hand, if you want to lose weight, I believe, as Locabo and Sugar Busters do, that reducing the percentage of carbohydrates in the diet and conversely increasing meat, fat, vegetables, and dairy products, etc. is effective.

In this case, the direct implication of reducing carbohydrates is to cut back on glucose that provides immediate energy. So, the body must obtain energy from protein (amino acids) and fat. It is also said to be useful in improving lifestyle-related diseases because it suppresses the rise in blood glucose levels.


The indirect effect is to send, conversely, dense nutrients into the intestines by increasing the proportion of indigestible food. Because of this, it takes us more time to digest and keeps undigested food in the intestines for a longer period of time.

As a result, we don’t feel being hungry so much, which in turn it decreases absorption ability. 

If you simply reduce overall food intake including meat, fat, and vegetable, etc., which means that you are "eating less and feeling hungry," and some studies have shown that such diets do not work in promoting weight loss in the long run. 

In other words, I believe that carbohydrates are not the culprit that directly make people fat. It is more important to eat in balance with relatively more meat, vegetables, cheese, and fat, etc., and to feel less hunger. 

Some people who advocate a low-carb diet say, "As long as you adjust your insulin secretion, you can eat anything without worrying about calories, even fatty foods, cheese, and meat. And since that's how you lost weight, it was the carbohydrates, not the caloric intake, that was the reason." 
I don’t think this explanation is correct.

[1]Satoshi Yamada, The Truth of Carbohydrate Restriction, (山田悟, 「糖質制限の真実」)2015, Pages 114-7.
[2]H. Leigton Steward, Morrison Bethea, Sam S. Andrews, and Luis Balart, Sugar Busters, 1998.

The bottom line

(1) Since around 2015, the low-carb diet has become a trend in Japan, not a fad diet. This is due to the fact that many people prefer diets high in carbohydrates (rice, bread, noodles, etc.) and along with that, obesity and diabetes are on the rise. (In fact, many still believe in the "calorie principle," so they are cutting back not only on carbohydrates, but also on calories.)

(2) In the U. S. (New Orleans), the Sugar Busters was a trend in the late 1900’s. This was more than fifteen years before a low-carb diet became a trend in Japan.

(3) Doctors and others who advocate low-carb diets say
that regulating insulin secretion is the key to this diet, but I beg to differ. I believe it is worthwhile to reduce carbohydrate intake while increasing the intake amount of meats, fat, vegetables, and dairy products, etc. This allows undigested food to remain in the intestines for a longer period of time, resulting in less hunger, which in turn reduces absorption ability.