The Endocrine System

The Endocrine system is a “network of glands that produce and release hormones that help control many important body functions” (Miller). Among the endocrine glands include the adrenal glands, pituitary gland, and thyroid. Hormones that are released by endocrine glands include estrogen, testosterone, insulin, glucagon, and epinephrine, and hormones play a role in regulating a range of processes from influencing how one’s heart beats to how one’s bones and tissues grow. 

Metabolism

According to the Mayo Clinic, metabolism is “the process by which your body converts what you eat and drink into energy.” Even when one is at rest, their body continues to carry out functions such as breathing and adjusting hormone levels, which require energy. The number of calories that one’s body uses to complete these functions is known as the basal metabolic rate. Depending on age, body size and composition, and sex, basal metabolism can vary from individual to individual. For example, as one gets older, the amount of muscle they have tends to decrease and naturally the rate of calorie burning will also decrease. Beyond one’s basal metabolic rate, food processing (thermogenesis) -“digesting, absorbing, transporting, and storing the food you consume” (Mayo Clinic)- and physical activity also determines the number of calories that one burns off in a given day.

Relating the Endocrine System to Metabolism

Hormones can be categorized based on the type of processes they influence within the human body. Adrenaline (epinephrine), norepinephrine, and cortisol are 3 major hormones that play a role in stress. While all 3 hormones are produced by the adrenal glands located on top of both kidneys, adrenaline and norepinephrine are greatly responsible for the immediate reactions one feels when stressed whereas cortisol takes effect after a few minutes. Though the body’s stress response is helpful during a fight or flight situation, long term stress actually plays a role in weight gain. When stressed, the levels of cortisol rise, causing the insulin levels to rise as well. As a result, one’s blood sugar drops and they crave “comfort foods” such as fatty and sugary foods that will calm them down and make them less stressed. Over time, the consumption of “comfort foods” in addition to low levels of physical or aerobic exercise may lead to unwanted weight gain.

Stress may play a role in weight gain but metabolic hormones such as insulin and glucagon are important when it comes to regulating the body’s blood sugar level and leptin and ghrelin directly influence one’s appetite. Both insulin and glucagon are released from the pancreas, but the two hormones have opposing roles. Insulin is released to decrease blood glucose levels by helping cells absorb glucose while glucagon is released to increase blood glucose levels by signaling the liver to release stored glucose. On the other hand, leptin suppresses one’s appetite while ghrelin induces one’s appetite. As the numbers of obese people has been increasing, it has been observed that among those who are obese levels of leptin are increased while ghrelin is decreased. This may seem somewhat counterintuitive but it is established that obese people are actually leptin resistant and hence don’t feel as full despite eating, causing them to eat even more.

Endocrine Disorders

In addition to weight gain caused by stress or obesity caused by hormonal imbalances, a number of different complications including diabetes, hyperthyroidism, hypothyroidism, Cushing’s disease, and polycystic ovary syndrome (PCOS) can also result from issues within the endocrine system.