Some experts say that, “if the total daily caloric intake is the same, it doesn't matter how many meals a day you eat," but I assure you that the number of times you eat definitely affects your weight gain (or loss).
Indeed, if total caloric intake alone were the direct cause of weight gain, then frequency might not matter much, but my theory, as I have explained many times, is different from that.

In this case, I think it doesn’t have much to do with how many meals you eat a day. Rather, it’s the caloric or carbohydrate intake that matters. People who normally keep their weight lower through dieting or who cut excess body fat through workouts can gain weight if their caloric intake is higher than necessary, regardless of the number of meals they eat.
　　

As for part (A), the frequency of eating has a lot to do with it. Since base weight itself goes up by inducing intestinal starvation, eating more frequently and in a more spread out manner is less likely to result in weight gain. When you feel a little hungry, other foods enter your stomach again, which means that undigested foods are more likely to remain in your gastrointestinal tract. 

Conversely, less frequency of eating and longer periods of time between meals can cause intestinal starvation, which can lead to an increase in base weight value.

Let me explain (A) when the base weight is increased.

Based on my idea, people tend to gain weight if they skip breakfast or lunch and eat only two meals a day. However, eating two meals a day does not necessarily make everyone overweight. 

Actually, how many meals you eat a day is a matter of "meal intervals," and is only one of the "three(+one) factors” conditions that induce intestinal starvation.

Three (+one) Factors to Accelerate “Intestinal Starvation”

The most important thing is, "what to eat." But in addition, a person's digestive ability and the way they eat (eating speed, number of times they chew, and hydration during meals, etc.) also have a great impact.

For instance, even if everyone eats exactly the same food, people who can digest them faster reach the state of intestinal starvation faster. Also, even if the number of meals is the same, the time of day at which you eat also makes a difference (late lunch, late dinner, etc.).

Let me explain this in greater detail with some examples.  

<A co-worker who gained weight with only one meal a day>

When I was working part-time in a restaurant in college, there was a co-worker who gained almost ten kilograms since he started working. 

He ate only the meal for employees there that was served at night and nothing else, which meant that he had one meal a day. In his high school days, it seemed like he could not gain weight even though he was eating three meals a day and more calories. 

<A friend of mine who gained ten kilos by eating four to five meals a day>

A friend of mine gained more than ten kilograms by eating four to five meals a day when he was studying for a college entrance exam after he failed the first try. He belonged to a judo club in high school, and was very thin, even though he ate a lot of calories. But please note that it is not that the five meals a day that makes you fat, but what you eat and how you eat that matter. 

Although I cannot make an assertion based on just the number of meals, I believe that increasing the frequency of your meals is one correct way to lose weight. According to a study by Professor Saeko Imai at Osaka University in 2014, there was a change in blood sugar levels in diabetic patients depending on what time of day they ate cookies. 

In some cases, observational studies that examine the "association between meal frequency and being overweight" may go wrong.

For example, suppose you survey obese or overweight people and asked them how many times a day they eat. Let's assume that most of them answered four to five times. But you cannot take the aggregate results and say, “eating four or five times a day makes you gain weight.” 

The reason for this is that the most important things are missing: what you eat, and how much you eat, etc. As I said earlier, if one hamburger or one cup of noodles counts as "one meal," it makes no sense.

Second, we never know if they gained weight because they ate many times, or they ended up eating as a result of being too hungry.

(1) Some experts say that, “if the total daily caloric intake is the same, it doesn't matter how many times you eat," but from my intestinal starvation theory, the number of meals definitely affects weight gain (or loss).

(2) The number of meals is a matter of "meal intervals" and is one of the "three(+one) factors," conditions that induce intestinal starvation. Although eating one or two meals a day tends to increase weight gain in the long run, the most important thing is "what you eat” and other factors also influence this.

(3) Increasing the number of meals may also help you lose weight. It is important to leave more undigested food in the intestines and to not feel hungry.

(4) Observational studies that only examine “the association between meal frequency and being overweight” are meaningless. The reverse causality may occur: some people are too hungry and as a result, eat four or five times a day.