my son weight is 15 kg .his weight is not increasing from the last one year. if he have any problem?

A. When growing kids don't gain weight as they should, it is called "failure to thrive." Failure to thrive is not a disease or disorder itself. Rather, it's a sign that a child is undernourished. In general, kids who fail to thrive are not getting enough calories to grow and gain weight in a healthy way.