Why doesn’t our mass grow by the same amount every month that we eat? What is the energy contained in food spent?

According to the rule of the food pyramid, no more than 10% of the energy can go to the next trophic level. It is these 10% that go towards gaining mass, the rest is spent on breathing, movement and work of the body, and is also dissipated in the form of heat.

In theory, a person needs to eat 10 kg of food to gain 1 kg. In fact, depending on the nutritional value of the food and the level of physical activity, weight can either increase or decrease with such consumption. In the first case, we artificially (for example, by exercising in the gym) spend more energy, in the second we get its excess, which accumulates in the form of mass.