Metabolism is a series of chemical reactions in the body, which convert the food we eat into the energy that we use for growth, movement and healing. Metabolic reactions occur simultaneously to keep us healthy.
Metabolism begins with plants and photosynthesis – the process whereby a plant absorbs energy from sunlight enabling it to create sugars from water and carbon dioxide. We eat the plants, taking in this energy as carbohydrates, which release glucose into the bloodstream to fuel the body. Digestive enzymes break protein from food down into its individual constituents, called amino acids. Fats are converted into fatty acids, and carbohydrates become sugars, all of which are slowly released into the bloodstream as part of the digestive process.
These nutrients enter the body’s cells through the blood and are used either to power the body, build muscle and repair damage or are stored for later use. So the process of metabolism is the building up of tissues, muscle and energy stores and the breaking down of energy stores and fat to generate energy when it is required.
The reverse is catabolism (destructive metabolism), which produces energy for cellular activity. Catabolism releases glucose, mostly from carbohydrates and stored fat, which provides energy to heat the body and enable movement on demand.
How fast is your metabolism?
Metabolism doesn’t just affect your ability to gain or lose weight!
The basal metabolic rate (BMR) measures how fast a person’s body uses energy (in calories) while at rest. If you eat too many calories, the body will store the energy as fat for later use. Those with a low BMR burn fewer calories while at rest and will have a tendency to gain weight.
Hormones play a key role in metabolism – eg thyroxine is a hormone produced by the thyroid gland which affects the speed of metabolism. An overactive thyroid can result in energy being used too fast, resulting in hyperactivity and weight loss. Insulin is released by the pancreas in response to elevated blood glucose -usually after meals. It pushes blood sugar into the cells and triggers an increase in anabolic activities.
It’s common for people to blame a slow metabolism for their weight problems, but usually this is untrue and more likely a result of poor diet and lifestyle choices.