The human body is made of the same materials as food. The nutrients the body needs in the greatest amounts include water, fat, protein and carbohydrates. A healthy 150 pound human contains 90 pounds of water, 30 pounds of fat and the other 30 pounds consists of protein and carbohydrates. The vitamin and mineral component of the body amounts to less than 1 pound.
The maintenance of the body involves both destruction and renewal of its parts. The destruction process is called catabolism (breaking down) and the renewal process is called anabolism (building up). Through the breakdown and rebuilding process, your body replaces about 400 billion cells per day. This process occurs at such a slow pace that you don’t even notice its happening. Your body makes you a new skin every month, the stomach lining transforms itself every 5 days, bones replace themselves every 3 months, you get a new liver every 6 weeks, etc.
Amino acids are linked together to form muscle tissue.
Glucose is stored in the liver and muscle tissue as glycogen.
Fat is stored inside fat cells as triglycerides.
Lean muscle protein is dismantled into amino acids.
Liver glycogen is broken down into glucose and released back into the bloodstream. Muscle glycogen is broken down and utilized within
Triglycerides (storage fats) are broken down into fatty acids and released into the bloodstream.
A person’s moment to moment metabolism is defined as the sum total of both anabolic and catabolic processes. To sustain life both of these processes must occur simultaneously. At any given time, your muscles are both building protein and breaking it down. If you are breaking down more than you are building, then a net breakdown will occur. This breakdown and repair process is what keeps us new. A dynamic, ever-changing system gives the body metabolic flexibility. If we didn’t have this “in vs. out” system, the body would be as responsive as a rock and unable to regulate itself.