The body sustains itself and adapts to its environment

The body sustains itself and adapts to its environment through metabolism. In order for metabolism to occur, the body needs both energy and building blocks for growth and repair. It gets its energy from the breakdown of nutrients such as glucoseketone bodieslactic acidamino acids, and fatty acids. To construct molecules for growth and repair, a delicate interplay must exist between anabolism and catabolism.

metabolism: The total of all the chemical and physical processes by which the body builds and maintains itself (anabolism) and by which it breaks down its substances for the production of energy (catabolism).

glucose: Principal circulating sugar in the blood and the major energy source of the body.

ketone bodies: Bodies produced as intermediate products of fat metabolism.

lactic acid: A by-product of glucose and glycogen metabolism in anaerobic muscle energetics.

amino acid: The building blocks of protein. There are 24 amino acids, which form countless number of different proteins.

fatty acids: Any of a large group of monobasic acids, especially those found in animal and vegetable fats and oils.

anabolism: The building up in the body of complex chemical compounds from simpler compounds (e.g., proteins from amino acids).

catabolism: The breaking down in the body of complex chemical compounds into simpler ones (e.g., proteins to amino acids).

The many biochemical processes that make up the body’s metabolism are categorized into two general phases: anabolism and catabolism. Anabolism and catabolism occur simultaneously—and constantly. However, they differ in magnitude depending on the level of activity or rest and on when the last meal was eaten. When anabolism exceeds catabolism, net growth occurs. When catabolism exceeds anabolism, the body has a net loss of substances and body tissues and may lose weight.

Anabolism includes the chemical reactions that combine different biomolecules to create larger, more complex ones. The net result of anabolism is the creation of new cellular material, such as enzymes, proteins, cell membranes, new cells, and growth/ repair of the many tissues. That energy is stored as glycogen and/or fat and in muscle tissue. Anabolism is necessary for growth, maintenance, and repair of tissues.

Catabolism includes the chemical reactions that break down complex biomolecules into simpler ones for energy production, for recycling of molecular components, or for their excretion. Catabolism provides the energy needed for transmitting nerve impulses and muscle contraction.

Metabolism includes only the chemical changes that occur within tissue cells in the body. It does not include those changes to substances that take place in the digestion of foods in the gastrointestinal system. For optimal function, a healthy metabolism needs many nutrients. A slight deficiency of even one vitamin can slow down metabolism and cause chaos throughout the body. The body builds thousands of enzymes to drive its metabolism in the direction influenced by activity and nutrition. So, when you are training or engaged in vigorous physical activity several hours a day, you must ensure that your diet contains the nutrients your body needs in order to optimize the many metabolic functions taking place.


Based on the discussion of homeostasis and metabolism, it is evident that the body is a highly regulated collection of many biochemical reactions. Much research over the years has revealed that the body seeks to maintain a certain base rate of metabolism, called the metabolic set point, which results in basal metabolic rate (BMR). This set point is regulated by both genetic and environmental factors. Researchers have demonstrated that you can change your metabolic set point through diet and physical activity.

metabolic set point: The base rate of metabolism that the body seeks to maintain; resulting in basal metabolic rate.

basal metabolic rate (BMR): The minimum energy required to maintain the body’s life function at rest; usually expressed in calories per hour per square meter of the body surface.

The metabolic set point is the average rate at which the metabolism runs, and it will result in a body composition set point. People with a slow metabolism seem to store fat easily, while people with a fast metabolism seem to be able to eat and never gain fat. Your metabolic set point can be influenced by the external environment (climate), nutrition, exercise, and other factors. Studies have demonstrated that when individuals go on a low-calorie diet, the body’s metabolic set point becomes lower in order to conserve energy. It actually resets itself to burn fewer calories, thereby conserving energy. Exercise tends to increase metabolic rate, causing the body to burn more fat for energy.

Calculating Caloric Expenditure

You can estimate your total daily caloric expenditure by multiplying the Harris-Benedict equations for basal metabolic rate by an activity level factor that accounts for your daily physical activity levels and the thermic effect of food.

thermic effect: The heat liberated from a particular food; it is a measure of its energy content and its tendency to be burned as heat. This process of heat liberation is also commonly referred to as “thermogenesis.

Bible verses for today’s meditation and inspiration: Matthew E. McLaren

Love is patient, love is kind. It does not envy, it does not boast, it is not proud. It does not dishonor others, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. 1 Corinthians 13:4-5  NIV

Do everything in love. 1 Corinthians 16:14 

Let the morning bring me word of your unfailing love, for I have put my trust in you. Show me the way I should go, for to you I entrust my life. Psalm 143:8 NIV

Let love and faithfulness never leave you; bind them around your neck, write them on the tablet of your heart. Then you will win favor and a good name in the sight of God and man. Proverbs 3:3-4 NIV

And over all these virtues put on love, which binds them all together in perfect unity. Colossians 3:14 NIV

And so we know and rely on the love God has for us. God is love. Whoever lives in love lives in God, and God in them. 1 John 4:16 NIV

Be completely humble and gentle; be patient, bearing with one another in love. Ephesians 4:2 NIV

We love because He first loved us. 1 John 4:19 NIV

Above all, love each other deeply, because love covers over a multitude of sins. 1 Peter 4:8 NIV

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