Many people say that eating too much fat or oil makes you fat, since fat has more than twice as many calories as carbohydrates or proteins per gram. But some research shows that some people can lose weight even though they increase fat or oil in diets.
Which is true?

To make a long story short, I think both are correct. As I have mentioned so many times before in this article, there are two meanings to the phrase “gain weight,” and based on my theory, I can say that eating fat has three sides to it.

He concluded :

• Low-fat diets are ineffective for weight loss.
  
• Dietary fat intakes are not strongly linked to body weight, and some evidence links increased fat intake with lower body weight.
  
• Insulin is the key driver of fat accumulation in the body. Dietary fat does not stimulate insulin secretion directly, and therefore has limited fattening potential.”
  
• Obviously, eating nothing but fat is not to be advised, but some study open up the possibility that a fat-rich diet may actually assist our weight-loss efforts.[1]
     

I’m not a specialist or researcher. Therefore, I’d like to avoid mentioning how insulin or other hormones work in the bloodstream. But I believe I can explain why low-fat diets are ineffective for weight loss vs fat-rich diets that may help our weight-loss efforts, based on my theory.
I will explain in the next section. 

Based on my experience, those who gained weight with fat or got slim with fat are both true, but these are because they are just different aspects of fat’s own nature. We can’t observe this same result if we just focus on “calories.” 

I can say that fat can be categorized into three groups based on the subject of intake (who) and/or the way of intake (how many, how often).
     

People who always put in time and effort for dieting, or ripped people who cut excess fat, will get especially fat in a few days if they eat a lot of chocolates, cakes, fatty foods, or deep-fried foods. The fattening effect seems especially acute when you eat carbohydrates and fats together.

With these images, many people reject a revolutionary suggestion of taking fat/oil in order to get slim, and that’s what makes this theory hard to accept.

As you can see in the range of (B) of the diagram above, when the base weight itself increases, fat will work as a deterrent force.(*1)  I’ve stated before that the base weight value increases by inducing intestinal starvation, and since fat takes longer to digest, if you frequently eat fat/oil, there will be less chance of triggering intestinal starvation.

(*1) For those who have a higher digestive ability for dietary fat, they may not experience a deterrent force. 

In any case, fat digestion is more complex than other nutrients and tends to inhibit intestinal starvation.

For example, if a thin person wants to gain weight, eating a lot of fat/oil at meals will hinder gaining weight. Have you ever wondered, “why was he/she not getting fat despite the fact that they were eating high calorie foods, such as cakes, cookies, deep-fried foods, or fatty foods?” In fact, a low-fat, easily digestible diet is more likely to make you gain weight in terms of increasing your base weight itself.
    

As Dr. Briffa whom I’ve mentioned above said, I also believe that "in a low-carb diet, increased fat intake is linked to lower body weight” is in a way correct, as though this doesn’t apply to everyone. 

It is generally believed that the reason is that fat, unlike carbohydrates, does not stimulate insulin secretion, but I will avoid mentioning that for now. Other than that, here is what I would like to add and explain based on my theory.

The time it takes for fat to be completely digested can be six to eight hours, depending on the amount of food eaten and how we combine different foods. Therefore, by consuming fat/oil every four to five hours, undigested food will remain in the stomach and the large part of the intestines for most of the day, which lead to decreased feeling of hunger and, in turn, reduced absorption ability (rate and amount).

As seen in low-carb diets, by decreasing carbohydrate intake to an extent and increasing the intake of fats, proteins, nuts, and vegetables, etc., dense nutrients are delivered to the intestines, which takes even longer to digest. If you continue with this eating habit, I believe it maximizes the dieting effect. 

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

(1) Just because fat has nine kilo calories per gram, does not mean that dietary fat always makes people fat. For those who normally keep their weight lower to lose weight, eating fatty food can be a cause of weight gain, but depending on the subject of intake (who) and/or how you eat it (how many, how often), fat can have a deterrent effect to further weight gain or diet effect.

(2)Fat takes longer to digest than other nutrients, so if you frequently eat fat, undigested food tends to remain in the intestines. This makes intestinal starvation less likely to occur, which tends to deter further weight gain in the sense that one’s base weight value doesn’t change.

(3)A diet low in carbohydrates but high in protein and fat may have a dieting effect. It is generally believed that the main reason is that fat, unlike carbohydrates, does not stimulate insulin secretion. My theory, I would add, is that ingesting fats every four to five hours will leave undigested food in the wide range of intestines, which will lead to reducing feeling of hunger and, in turn, decreased absorption ability. Continuation of this condition could have a weight-loss effect.