Body Basics: Metabolism
Ever know someone who can eat as much as they want and never gain weight? Chances are, they’ve given the age-old, “I just have a fast metabolism” reasoning. But is there any truth to that? And what are the determining factors of a fast and slow metabolism?
What is Metabolism?
Metabolism is a system of hormones and enzymes that help convert food into energy and also determine how efficiently energy is burned. In other words, a person’s metabolism establishes how quickly they burn calories and how easy it is for them to gain or lose weight. However, every individual burns calories at a different rate.
Several factors can influence a person’s metabolism such as age, sex, and body composition. Metabolism has been found to slow approximately 5 percent per decade after the age of 40. What’s more, men tend to burn more calories while at rest than women. Studies also show that the more muscle a person has, the higher the metabolic rate tends to be.
Food = Energy
While dining on your favorite foods can be enjoyable, it’s important to remember that the essential function of food is to provide the body energy. This is where metabolism plays a huge role. At the most basic level, your body needs energy to carry out necessary functions, such as breathing, circulating blood, adjusting hormone levels, and repairing and generating cells.
The energy (calories) needed to carry out these basic functions is known as the basal metabolic rate. The basal metabolic rate is responsible for approximately 60-75 percent of calories burned every day.
Besides the basal metabolic rate, two other main factors determine the amount of calories burned each day. The first is called thermogenesis, or the energy needed to process food. This accounts for digestion, absorption, transportation, and storage of calories consumed. On average, thermogenesis makes up approximately 10 percent of a person’s calories total calories burned each day.
The second factor is physical activity. This accounts for the rest of a person’s calories burned each day. This can be any form of exercise from walking to running to playing Frisbee, as long as energy is expended. While the type and amount of exercise each person participates in is different, this is the most variable factor when it comes to determining the amount of calories burned.
Metabolism and Weight
While metabolism is closely linked with body weight, it generally cannot be blamed for weight gain. That’s because the body works to balance metabolism based on an individual’s needs. For example, a person attempting to lose weight by starvation will not suddenly shed pounds because their body’s metabolism will be alerted to slow dramatically and conserve calories for survival.
While there is no magic way to control your metabolism, you do have control over physical activity and calories consumed. For individuals trying to lose weight, it is suggested to decrease the intake of calories and increase the amount of physical activity. The more active you are, the more calories you burn. Aerobic exercise like walking, running, or biking is a simple and effective way to burn calories on a daily basis. It is recommended that adults do at least 30 minutes of physical activity each day.
Strength training, like lifting weights, is also an effective way to burn calories. It also helps to build muscle, which has been shown to burn more calories than fat tissue. It is highly suggested to avoid crash diets, as these tend to limit nutritional intake and decreases muscle mass, which can be dangerous.
While physical activity is important in impacting metabolism, diet can also play a part. Dehydration has been shown to slow metabolism, therefore drinking enough water and liquids throughout the day is key. The body also burns more calories digesting protein than it does for fats of carbohydrates.