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. 
The primary reason for baseline deficiencies in both the general population and in serious athletes is that it's difficult to get proper amounts of zinc and magnesium solely through diet alone. USDA studies show that 68% of self-selected diets contain less than two-thirds of the RDA for zinc  and 39% contain less than two-thirds of the RDA for magnesium.  While zinc and magnesium are contained in a wide variety of foods, it's been my experience that athletes don't acquire sufficient quantities through their normal diets. One reason may be that foods high in these minerals aren't necessarily the most desirable. For example, the best food sources for zinc include oysters and beef liver. These foods aren't consumed by most athletes, nor should they be.