The title is quite banal, but many people and even "pseudo-specialists" still do not understand the fundamental rules of our metabolism, thereby harming themselves with a special diet, or, for example, stupid workouts.
And so, we have all heard that if you eat a lot of high-calorie food, you can gain weight. Let's first find out what the calorie content of food is. This is the amount of energy that our body receives during the biochemical processing of this food. To understand the essence of calorie content, non-physicists need only imagine how two substances of the same mass \ volume burn, for example, alcohol and diesel fuel (diesel fuel), which of them will give more heat? Anyone who has ever seen such combustion will immediately answer - diesel fuel. That is, its calorie content is higher (~ 10300 kcal / l., versus ethyl alcohol ~ 7000 kcal / l). So with food, some products give a lot of heat \ energy, others less. We found out.
Now let's imagine the situation of a hypothetical person who constantly eats a lot of high-calorie foods, will he increase his body weight? To this question, fitness trainers unanimously answer - "yes, in such conditions he will always gain weight"
Я же отвечу — не факт 
Человек будет повышать свой вес только на вес еды, что вошла в его ЖКТ. А вот будет ли увеличиваться вес его жировой ткани, мышечной ткани и других тканей уже очень зависит от процессов его индивидуального метаболизма. У всех вас наверное есть знакомый\знакомая что кушает все подряд и не толстеет. Вот теперь я расскажу почему так происходит.
The thing is that the "fuel" that enters the body in the form of food is "processed" differently by each person to obtain energy. Moreover, there can be both safe genetic layouts and pathological ones. I will give the most popular variants of pathologies:
A person has low acidity in the stomach, as a result, the protein breakdown reactions slow down (such reactions require an acidic environment with a certain pH). Usually, such people have a poor appetite and an aversion to meat. Some individuals, under the influence of idiots from the Internet, begin to think that this is a sign to become a vegan.
A person's gastrointestinal tract does not work properly, for example, the number of enzymes / bacteria for breaking down proteins into peptides, fats into fatty acids, carbohydrates into glucose decreases.
A person has problems with anabolic hormones. For example, there is a loss of growth hormone secretion, low insulin levels, low levels of androgens or estrogens.
With all these scenarios, no matter how much high-calorie food you eat, you won’t gain weight! Because the food won’t go through all the necessary stages of biochemical processing to obtain energy.
Moreover, if you add physical activity (like going to the gym to a trainer who has completed a trainer course:) ) then you will harm your body even more! The body will experience a deep deficit of energy that you spent on exercises but cannot fully restore with meals.
Поэтому, если у вас годами не выходит набрать вес, а именно вес мышечной ткани (так как набрать вес жировой ткани это не польза ), в первую очередь обследуйте свое тело на наличие вышеописанных проблем у толковых специалистов, или разберитесь в этом самостоятельно. И только после решения проблем нагружайте свое тело едой и физ. нагрузками.
