The Dilution Effect/ Pushing Out Effect of Carbohydrates: Does This Cause People To Gain Weight?


  1. If there were no carbohydrates
  2. With indigestible foods, it is difficult to gain weight
  3. The effect of carbohydrates that make it easier to gain weight
    (1) Dilution Effect
    (2) Pushing out Effet
    The Bottom Line

When we consider that “eating a lot leads to gaining weight,” I believe you have the image of carbohydrates like bread, rice, and noodles in mind.

This time, I am going to explain the reason why carbohydrates (*1) make it easier for people to gain weight, not because of an increase in calories or of its tendency to raise blood sugar levels, but by other indirect ways.

(*1) Although technically sugar is also a sort of carbohydrate, I use the word carbohydrate here to mean polysaccharide” such as starches, bread, and rice.

1. If there were no carbohydrates

When my total body weight fell to under forty kilograms, it would have been impossible to have gained weight without the help of carbohydrates.

In my case, neither fat nor sugar could have done that... In other words, I would never have gained weight by eating cream-filled cakes or oily pork cutlets and fatty Chinese food. Next, I am going to explain the reason why.

To be precise, I don’t mean all carbohydrates, just refined digestible carbohydrates such as white bread, rice porridge, potatoes, starches, etc.

Thus, in the case of brown rice, fried rice, whole-grain bread, cold rice, and al dente cooked pasta, etc., the result may be different, even though they are the same type of carbohydrates. These are known as foods that won’t increase blood sugar levels much (low glycemic index, resistant starches) but in short, they are indigestible.

2. With indigestible foods, it is difficult to gain weight

When you always eat indigestible foods, such as the above-mentioned carbohydrates that don’t raise the blood sugar level, fat, fibrous vegetable, seaweed, and dairy products, intestinal starvation is less likely to occur and you are less likely to gain weight, which means the base weight value in my definition is unlikely to go up.

Two meaning to the phrase 'gaining weight'

I’m simply saying that it is hard to gain weight if a thin person eats them properly every day.
Although a person who has already gained weight (or who is already overweight) may not lose weight by eating some indigestible foods, I consider that it may be possible to lose weight depending on how you eat them, since these foods are always discussed in dieting techniques.

3. The effect of carbohydrates that make it easier for people to gain weight

On the contrarily, refined digestible carbohydrates (rice, rice porridge, white bread, potatoes, starches, etc.) will promote digestion. By eating them together with digestible proteins, they make it easier to  induce intestinal starvation. Those are two effects that I can think of so far.

(1) Dilution Effect 

If you proportionally increase digestible carbohydrates in the meal, the percentage of side dishes such as fat, meat, fish, and vegetables will be relatively smaller. The density of a spoonful of oil will be lower if you eat more bread or rice portions with soup (water). 

meat and bread

When you eat some meat together with a slice of bread and soup, the density of the meat will be lower.

In other words, easily digestible carbohydrates and water are added and mixed in the stomach, and then the diluted nutrients are sent to the intestines. So, it will be easier to get hungry and induce intestinal starvation.

For example, let’s say you eat a hamburger and a potato, plus another piece of bread and tea. If we mix all of these in a blender, it will be something like meat diluted with starch and water.

Dilution effect

In contrast, if we remove the bread and add mixed beans-mayonnaise salad… the dilution effect of carbohydrates will be less, and fiber and fat will be added.

On a caloric basis, mixed beans-mayonnaise salad is, e.g. 100kcal. However, adding it to the meal doesn’t have the same meaning as adding another piece of bread. This is why calorie intake basis thinking may go wrong.

Mixed beans

Moreover, as seen in low-carb diets, what would happen if you decrease the intake of carbohydrates  in the meal and instead increase proteins such as meat and fish, fat, and vegetables? 

In this case, the opposite effect of the dilution effect occurs: dense nutrients are delivered to the intestines, which slows digestion and undigested food always remains in the gastrointestinal tract.

(2) Pushing out Effect 

"Balloon effect"

When we eat carbohydrates together with water, our stomach expands (I’ll call this the “balloon effect” of the stomach). And, if we eat carbs together with digestible side dishes such as stew (onion, potatoes, low-fat chicken, etc.), its holding time in the gut will be shorter since it’s easy to digest, and the food will be pushed out of the stomach fairly soon. Also, our intestines start to move actively and smoothly.

Soba noodle and rice

I had the problem with my stomach and intestines and often suffered from constipation or diarrhea.

But, when I ate Japanese soba noodles(*2) and small rice bowl dishes (chicken and egg over rice), it promoted regular bowel movements and relieved my symptoms several times.

(*2) If you don't know much about it, it may be easier to imagine ramen noodle and rice. 

On the other hand, you may think that eating fatty foods or deep-fried foods give us stamina. It actually means that those foods fill us up better than carbs do, and its energy could be sustained during sports such as a marathon or a soccer match.
That is to say,
undigested foods stay longer in our stomach and intestines, so it’s more difficult to induce intestinal starvation.

The Bottom Line

(1) Simply put, poorly digestible foods are not fattening. In contrast, refined grains, starches, and other easily digestible carbohydrates tend to make people fat. These polysaccharides may have a "dilution effect" or "push-out effect" in the digestive process.

(2)I consider sugar (monosaccharides, disaccharides) and polysaccharides (starch, flour, rice, etc.) can not be put into the same category since they have different characteristics based on my theory. Recent popular low-carb diets focus primarily on the blood glucose-raising properties of carbohydrates, which alone is not a sufficient explanation for why it is necessary to add more meat, fat, vegetables, and other side dishes in the diets.

(3) Obesity among poverty-stricken people worldwide can be understood as the influence of cheap refined carbohydrates and unbalanced diets (lack of vegetables, etc.). Considering them, it may be easier to imagine that they are not gaining weight due to taking too many calories or sugar, but rather from consuming cheap carbohydrates as mentioned above.
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Wealthy People Get Fat? Poor People Get Fat?

(4) Also, the fact that sumo (Japanese national sports) wrestlers eat digestible hot pot dishes called “chanko” with a lot of rice two times a day in order to make their bodies larger is a very logical view in this sense.