Weight Loss

Metabolism and Weight

Are weight issues due to a slow metabolism? It’s true that metabolism is linked to weight. But medical problems that slow metabolism, such as Cushing’s Syndrome or having an under active thyroid gland -hypothyroidism- are rarely the cause. Although your metabolism influences your body’s basic energy needs, diet and your level of physical activity ultimately determine your weight. Understanding your metabolism and how to rev it up, can make a difference.

According to the Mayo Clinic, metabolism is the process by which your body converts what you eat and drink into energy. Calories in food and beverages are combined with oxygen to release the energy your body needs to function. 

For most people, actual exercise only accounts for 10% of their metabolism.

Metabolism is closely linked to nutrition and the availability of nutrients from our diet. That’s why eating healthy is so important. Energy formation is one of the vital components of metabolism. The thyroid gland, a small butterflyshaped gland located at the front of your neck, near the Adam’s apple, controls metabolism. Metabolism then determines the rate at which your body is able to convert food into energy. The brain sends messages to this “master control” when it comes to energy and protein production, hormone regulation, and other bodily processes (i.e., digestion). Think of the thyroid as the engine within your cells that keeps you going. A car runs on gas; you run on calories- units of energy. 

70% of the body’s calories are burned simply doing its job: 

  • Fueling your cells and keeping your heart pumping, 
  • Maintaining blood circulation
  • Lung function
  • Adjusting hormone levels
  • Growing and repairing cells
  • Keeping your digestive system working
  • Ensuring energy to keep brain neurons firing  (in fact, your brain alone needs about 420 calories a day just to keep functioning)

You’re always incinerating calories, even while asleep. The number of calories your body uses to carry out basic survival functions is known as your basal metabolic rate (BMR)what we generally refer to as metabolism.  After you eat, the body breaks food down into its simplest forms of carbohydrates, protein, and fat. The calories in those components are then converted to energy, used by your cells and tissues for all their necessary actions. As your body breaks down your meal, your brain gets feedback signals — from the nutrients, your hormones, and how much you’re moving around — and “decides” whether to use the calories right then, or store them.

Remember, it takes 70% of ingested calories burned to maintain all survival functions (the BMR). The activity you do all day that isn’t deliberate (non- exercise adaptive thermogenesis, NEAT) such as walking from room to room, shivering, even fidgeting accounts for 20% of the calories burned, or about 100 to 800 calories used daily. Actual exercise only accounts for 10% of most peoples metabolism.

Several factors determine individual basal metabolism, including:

  • Your body size and composition: People who are larger, or have more muscle, burn more calorieseven 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: Metabolism steadily slows after the age of 40. The amount of muscle tends to decrease and fat accounts for more of your weight as you age, slowing down calorie burning.
  • GeneticsYou may have a naturally faster or slower metabolism, though lifestyle still has a big impact.
  • Stress: long term stress releases hormones that interfere with digestion, so food isn’t used as efficiently.
  • SleepThis is critical. When your body is short on sleep, it’s pushed into conservation mode, so you burn fewer calories.
  • Physical activity: Physical activity and exercise is by far the most variable of the factors that determine how many calories you burn each day.
  • Activity level: When you are more active during the day through routine daily movements like walking or standing, your body burns more calories.
  • Hormones: If thyroid hormones are not produced properly by your body, your metabolism may increase or decrease, depending on the hormone level.
  • Food intake: It’s not just what you eat, but how much as well. If you don’t eat enough food, your metabolism slows.
Next week, I’ll discuss tips on how to ramp up and improve your metabolism.
    – Dr. Courtney

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