Metabolism can be a confusing concept to understand, but it is critical to how children grow and develop. All the cells in a child’s body use a tiny amount of energy to divide and make copies of themselves, and the do it all by themselves. They do this by breaking down the nutrients and extracting the energy from them – this is called “metabolism”.
Some cells have a higher activity, like those that make up the muscles, heart, brain and eyes. Those use more energy, more quickly. Adding up all the billions of cells together, you will have a total amount of energy (in calories or kilojoules) per hour for the whole body, and this is called “metabolic rate” .
It is also what generates heat in the body. Metabolism is steady (also called “basal”) when kids are sitting down, but increases when they move around, run, jump and play. The energy used is controlled by the individual tissues, but they are all coordinated by a hormone called thyroid hormone. Another observation is that children also have a high metabolic rate for their body size than adults, because they lose more heat.