Catabolic processes are those that involve the breaking down of complex biological tissue into simpler, smaller units that can take part in respiration reactions and combine with oxygen to release energy. Anabolic processes on the other hand begin with simple units that combine with each other; there is a formation of new bonds that results in more complex tissue being formed. Anabolic processes require energy to take place.
If a person is consuming more energy than that is expended by the body, it leads to anabolic processes taking place in the body. The extra food that is consumed is used to build new tissue, if the person is taking part in activities that aid in the building of muscle it leads to muscular tissue being built up. Else, the extra energy containing food is converted to fat and stored as fat tissue. The body does not expel any energy rich food that is eaten as it can convert protein and fat to energy in the future when sufficient energy is not being consumed.