Nutrition is the key to metabolism. The pathways of metabolism rely upon nutrients that they breakdown in order to produce energy. This energy in turn is required by the body to synthesize molecules like new proteins and nucleic acids (DNA, RNA).
Nutrients in relation to metabolism encompass factors like bodily requirements for various substances, individual functions in the body, the amount needed, and the level below which poor health results.
Essential nutrients supply energy (calories) and supply the necessary chemicals which the body itself cannot synthesize. Food provides a variety of substances that are essential for the building, upkeep, and repair of body tissues, and for the efficient functioning of the body.
The diet needs essential nutrients like carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, and around 20 other inorganic elements. The major elements are supplied in carbohydrates, lipids, and protein. In addition, vitamins, minerals and water are necessary.
Metabolism: Converting food into energy
Metabolism is the process by which your body converts what you eat and drink into energy. During this complex process, calories in food and beverages are combined with oxygen to release the energy your body needs to function.
Even when you’re at rest, your body needs energy for all its “hidden” functions, such as breathing, circulating blood, adjusting hormone levels, and growing and repairing cells. The number of calories your body uses to carry out these basic functions is known as your basal metabolic rate — what you might call metabolism.
Several factors determine your individual basal metabolism, including:
- Your body size and composition. People who are larger or have more muscle burn more calories, even at rest.
- Your sex. Men usually have less body fat and more muscle than do women of the same age and weight, which means men burn more calories.
- Your age. As you get older, the amount of muscle tends to decrease and fat accounts for more of your weight, slowing down calorie burning.
Energy needs for your body’s basic functions stay fairly consistent and aren’t easily changed.
In addition to your basal metabolic rate, two other factors determine how many calories your body burns each day:
- Food processing (thermogenesis). Digesting, absorbing, transporting and storing the food you consume also takes calories. About 10 percent of the calories from the carbohydrates and protein you eat are used during the digestion and absorption of the food and nutrients.
- Physical activity. Physical activity and exercise — such as playing tennis, walking to the store, chasing after the dog and any other movement — account for the rest of the calories your body burns up each day. Physical activity is by far the most variable of the factors that determine how many calories you burn each day.
Scientists call the activity you do all day that isn’t deliberate exercise nonexercise activity thermogenesis (NEAT). This activity includes walking from room to room, activities such as gardening and even fidgeting. NEAT accounts for about 100 to 800 calories used daily.
Related: The Best Metabolism Supplement
Metabolism and weight
It may be tempting to blame your metabolism for weight gain. But because metabolism is a natural process, your body has many mechanisms that regulate it to meet your individual needs.
Only in rare cases do you get excessive weight gain from a medical problem that slows metabolism, such as Cushing’s syndrome or having an underactive thyroid gland (hypothyroidism).
Unfortunately, weight gain is a complicated process. It’s likely a combination of genetic makeup, hormonal controls, diet composition and the impact of environment on your lifestyle, including sleep, physical activity and stress.
All of these factors result in an imbalance in the energy equation. You gain weight when you eat more calories than you burn — or burn fewer calories than you eat.
While it is true that some people seem to be able to lose weight more quickly and more easily than others, everyone loses weight when they burn up more calories than they eat. To lose weight, you need to create an energy deficit by eating fewer calories or increasing the number of calories you burn through physical activity or both.