The answer could be both! It is well known the thyroid gland is considered the regulator of our metabolism, and without proper thyroid function, our metabolism can suffer. However, if we do not give the body proper nutrition to maintain optimum functioning, a decrease in physiological processing can be the end result. Our metabolism, or basal metabolic rate, is the amount of energy, in the form of calories, that your body burns to maintain itself. Calories are expended for brain power, kidney function and liver processes, just to name a few. Metabolism is a continuous process that goes on every moment of your day, even when you are sleeping! With every organ of the body reliant on energy, our metabolic rate is a large player in our overall health.
Symptoms of a slow or low metabolism
While symptoms of a low metabolic rate can vary, common symptoms can include:
- Waking unrefreshed in the morning
- Feeling tired at various times of the day
- Lack of stamina
- Brain fog or lack of mental clarity
- Inability to focus
- Weight gain
- Lack of weight loss even with exercise and diet
- Weight gain without changing dietary habits
- Dry skin
- Dry and cracked skin
- Dry eyes or lips
- Lack of bowel movement for 2 or more days
- Dry or hard bowel movements
- Other symptoms
- Hair loss
- Joint aches and pains
- Menstrual irregularities in females
- Temperature intolerances
When the Thyroid goes Awry
It is important to rule out any physiological causes for low metabolism, including hypothyroidism. Blood tests can be run to determine your level of TSH, or thyroid stimulating hormone, which is routinely done to screen for hypothyroidism. TSH comes form the pituitary gland, knocks on the door of the thyroid gland, and asks for it to release a hormone called T4. T4 then comes from the thyroid to the periphery to be converted to T3, which is the active form of thyroid hormone, the type that maintains metabolic rate. Tests can also be run to determine your levels of T4 and T3 hormones.
There are several intermediate nutrients that are essential in the derivation of and conversion of T4 to T3, including, L-tyrosine, iodine, zinc, selenium and copper. When these nutrients are low due to lack of dietary intake or lack of absorption, the active from of thyroid hormone ceases to be produced in sufficient enough amounts to support proper metabolism.
Reasons for low metabolism
Several medications can inhibit the absorption of the nutrients needed for active thyroid hormone production including proton pump inhibitors, anti-cancer medications and antibiotics to name a few.
Vegetarians are at a higher risk of becoming zinc and L-tyrosine deficient as they are found in high amounts in meat products. However, soy, some seeds and nuts, and fruits contain L-tyrosine while pumpkin seeds, dark chocolate and peanuts contain zinc. Brazil nuts, seeds and fish are great sources of selenium while oysters sesame seeds and cocoa are high in copper. Iodine is found in highest amounts in sea vegetables like seaweed and kelp. Ensuring a balanced diet rich in all metabolism intermediate minerals and amino acids will aid in the maintenance of proper thyroid hormone conversion.
Lack of exercise
Exercise reduces fat mass and increases muscle mass. Muscle is much more metabolically active than fat is, meaning it is burning calories even while at rest! When we don’t exercise, our body readily depletes our muscle mass and replaces it with fat mass which further slows metabolic rate.
Stress can also be a component in decreased thyroid function. The body releases the hormone cortisol when under stress, which has been shown to inhibit the conversion of T4 to T3 when circulating in high amounts in the body. Therefore, stress management can play a huge role in improving metabolism.
How to determine Metabolic Rate?
A calculation can be done based on your height, weight, gender and age to determine your basal metabolic rate.
Basal Metabolic Rate Calculator:
Female: Basal Metabolic Rate = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) – ( 4.7 x age in years )
Men: Basal Metabolic Rate = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) – ( 6.8 x age in year )
Based on this calculation, in addition to making adjustments for your daily activity and exercise, you come to a grand total of daily calories to be consumed in a day to maintain proper functioning.