Carbohydrates make it easier for people to gain weight, its meaning other than just calories

  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 higher blood pressure, but by other indirect meanings.
(*1) Although technically sugar is also a sort of carbohydrate, I use the word carbohydrate here to mean “polysaccharide” such as starches and grains.

1. If there were no carbohydrate

  When my total body weight fell down to around 35kg, it would have been impossible to have gained weight without the help of carbohydrates. In my case, neither oil (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 Chinese food. I am going to explain the reason next.
  To be precise, I don’t mean all “carbohydrates,” but just refined digestible carbohydrates (such as white bread, rice, potato, starch etc.).

  Thus, in the case of brown rice, fried rice, whole-grain bread and al dente cooked pasta etc., the result may be different even though they are the same carbohydrates. These are known as foods that won’t increase blood sugar levels (glycemic index, resistant starch) 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-referenced carbohydrates that don’t increase the blood sugar level, oil (fat), high-fiber vegetable, seaweed and dairy products, it can be said that it is difficult to gain weight: “Base Weight” in my definition is unlikely to go up.
  As I have already explained, each person’s Base Weight level will not go up since the body recognizes that “the state which undigested foods are still in the intestine” = “there are still foods” → “there is no need to store.”
  I’m saying that it is difficult to gain weight if a thin person eats properly every day.
  Although a person who has already gained weight may not lose weight by eating some, I consider this 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

  Contrarily, refined digestible carbohydrate (rice, white bread, potato, starch etc.) will promote digestion. By eating together with digestible side dishes (meat and fish with less fat), they make it easier to create hunger.
  That is to say, “intestinal starvation state” will be occur more easily.There are 2 effects that I can think of so far.

(1) Dilution Effect 

  You may have heard the word “PFC Balance (protein, fat, carbohydrate)” and currently in Japan, it is said to be ideal to take 50 to 65% of energy from carbohydrate in average (Food Intake Standard-2015). However, I believe many people take still around 70%.
  If you proportionally increase digestible carbohydrates, 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 add water by doubling your bread or rice portions.
  Raw egg is indigestible but if you eat together with bread and coffee, the density of the egg will be lower.

  If the amount of side dishes are the same for everyone, the one who has relatively more carbs and water will be sending diluted nutrition to the intestine. So it will be easier to be hungry (intestinal starvation).
  For example, let’s say I eat a hamburger and a potato, another piece of bread and tea altogether.

  If we mix these all in a blender, it will be something like meat diluted with starch and water.(figure below)

  If I remove the bread and add broccoli mayonnaise salad… The dilution effect of carbohydrates will be less and fiber and fat will be added.

※ On calorie basis, broccoli mayonnaise salad is about 70 to 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.
  On the other hand, what would happen if I proportionally decrease carbohydrate? As you can see in low-carb diet, if I decrease the carbohydrates of the main meal and increase proteins such as meat and fish, oil or vegetables, I can send nutrition of higher density to my intestine.

  In this case, there will be the reverse effect that secures nutrition and causes less hunger. Moreover, since our intestines are long, about 6 to 7m, while the food is still inside our intestines, there will be indigestible substances that prevents intestinal starvation.

(2) Pushing out Effect 

  When we take carbohydrates together with water, our stomach expands (“balloon effect” of stomach).

  However, if we take carbohydrates together with digestible side dishes such as stew, its holding time will be shorter and the food will be pushed out of the stomach soon. Also, our intestine starts to move actively.
  For a foreigner, it may be easier to imagine instant noodle and toast or rice.

  Though our stomach does expand after we eat, since it’s easy to digest, it will start moving actively and smoothly. I had the problem with my stomach and intestines and suffered often from constipation or diarrhea, but this resolved it several times. And not just that our stomach starts to move but since the foods are digestible, it will be easier to be in an intestinal starvation state.
  On the other hand, though there are people who say taking meals with a lot of oil (Chinese food or fried food) will give us stamina, it actually means that it stays in stomach for a longer time and its energy could be sustained during sports. That is to say, since its holding time in stomach will be longer, it will be more difficult for us to become hungry (intestinal starvation).

■Lastly, taking into account the reasons stated above,

(1) I consider sugar (monosaccharide, disaccharide) and polysaccharid (starch, cereal) can not be put into the same category since they have slightly different characteristics.
  Recently-popular low-carb diets pay attention only to the “characteristics that increase blood sugar rate easily” so I don't believe it’s sufficient.
(2) Obesity among poverty stricken people worldwide can be understood as the influence of cheap carbohydrates (cereal, starch) and unbalanced foods (lack of vegetable etc.). Considering them, it may be easier to imagine that they are not gaining weight due to taking too much calories or sugar, but rather from consuming cheap carbohydrates as mentioned above.
(3) Also, the fact that Sumo wrestlers (Japanese national sports) eat hot pot dishes called “Chanko-nabe” with a lot of rice in order to make their bodies larger is a very logical view in this sense.