The basic factor of gaining weight is the intake of high amount of calories from food. Calories are the great source of energy which requires alot in our everyday's body functions but when these calories are not fully utilized by body then extra amount of it get store in the form of fats. It means;
INTAKE CALORIES - USED CALORIES = FATS
Life is impossible without food because it not only provides energy but also the other vital elements to your body. As the building requires the cement blocks and rods as it's base material same is the case here, so the costituents found in food acts as building blocks for the growth of body without which a body can't stand. These building blocks helps in growth of harmones, formation of DNA, save body from different damages and various other functions performed by body. For this purpose the intaked calories have to be change in the form required by body ,i.e, energy. When the food get converted into energy it is then become able to utilized, and the process of this conversion is said to be as 'metabolism'. When food get metabolized, it creates some heat(energy) in your body which can be measured in 'kilo calories'. Every food item contains same kind of calories for example,
1500 calories from Cauliflower = 1500 calories from Fruit Salad = 1500 calories from Chocolate
If you will take a bowl of yogurt contains 78 calories then same amount of energy will be gain by your body. Your body use it as per it's requirement and the unutilized will get store in the form of fats. Everyone's body is not exactly the same but can differ in performing their functions like, it is individual's own body ability to store extra calories. A harmone is found in our body named as 'insulin', which usually related by people with diabetes, is an important factor that helps to store fats. If you try to balance the level of insulin in blood, it can help you in losing your weight. If you eat the nutrientious food you can maintain it's level.
The basic matter is not to gain calories by various food items but to utilize it in a proper way. By the best utilization of it you can not only gain the better health but it also helps you in losing your weight. For this purpose you must have to know that how the energy is required and used by your body. The basic way in which it is used and flourishes yourself is that, it required by your body at each and every moment whether you are sleeping or not. Because at every moment your heart is beating, blood is circulating, brain is working and even you are breathing. Infact the other functions which can't be felt by us requires the same energy like, the energy used by each and every cell of your body.
Though a very high amount of it is required but you should have to be careful about the intake of calories and keep a proper check on it because, on the one hand it keeps your life in working but on the other hand it can makes you fat. So this is all about that ' how calories become a factor of your weight gain'.