Anabolic processes tend toward "building up" organs and tissues . These processes produce growth and differentiation of cells and increase in body size, a process that involves synthesis of complex molecules . Examples of anabolic processes include the growth and mineralization of bone and increases in muscle mass. Endocrinologists have traditionally classified hormones as anabolic or catabolic, depending on which part of metabolism they stimulate. The classic anabolic hormones are the anabolic steroids , which stimulate protein synthesis, muscle growth, and insulin . The balance between anabolism and catabolism is also regulated by circadian rhythms , with processes such as glucose metabolism fluctuating to match an animal's normal periods of activity throughout the day. 
For children, these reactions should not be in balance. In a child, the anabolic reactions have to be greater than the catabolic. Boys start their growth spurt after girls. That’s why when they are in 7th or 8th grade, the girls are still taller than the boys. The boys change a couple years after the girls. Guys may gain 2-3 inches in that growth spurt between 14-17 years of age. During that growing period they will eat up all the food in your refrigerator. They are growing like crazy during that time. But what happens to both boys and girls at 18-19 is that if they keep eating the same way, they won’t grow taller anymore but only wider. This is the phenomena everybody notices.
Nutrition genes (nutrigenetics):