These hormones regulate almost every cell and organ, and function in our body. The endocrine system and the hormones it secretes are extremely important in health issues such as obesity. Hormones play a role in appetite regulation, regulating metabolic rate, and stimulating fat synthesis. We are seeing more and more the roles and effects that these hormones have on weight. Cortisol is a hormone that has been shown to have a profound affect on weight.
Cortisol is a corticosteroid hormone that is secreted by the adrenal cortex. Cortisol plays a role in the maintenance of plasma glucose during long-term fasting and exercise by a variety of mechanisms. Such mechanisms include:
- Promoting the breakdown of tissue protein to form amino acids, which are then used by the liver to form new glucose
- Stimulating the mobilization of free fatty acids from adipose tissue
- Stimulating liver enzymes involved in the metabolic pathway leading to glucose synthesis
- Blocking the entry of glucose into tissues, forcing those tissues to use more fatty acids as fuel
Cortisol is secreted in a pattern called diurnal variation, which means that levels of cortisol vary depending on the time of day. Cortisol is usually higher in the morning and lower at night. Cortisol stimulates fat and carbohydrate metabolism for fast energy, and stimulates insulin release and maintenance of blood sugar levels. Both of these actions can cause an increase in appetite.
The Stress Hormone
Cortisol is known as the “stress hormone” due to excess cortisol being excreted during times of physical and physiological stress. Cortisol has been shown to not only affect weight gain, but also where weight is put on. An elevation in cortisol levels has been shown to cause fat deposition in the abdominal area. A high amount of fat in the abdominal area has been correlated with cardiovascular disease, heart disease and stroke.
Cushing’s syndrome is a disease that is caused by prolonged and abnormally high levels of cortisol. Cushing’s syndrome is a relatively rare disease, but is seen in individual ages 20-50 that have ailments such as obesity, type II diabetes, and high blood pressure. This disease causes a high amount of cortisol to be secreted and in turn an increase in weight. For people who do not have this disease the weight gain from cortisol is related more to stress levels.
Fight or Flight Syndrome
Stress causes a rise in the "fight or flight" response in the sympathetic nervous system. This response triggers the release of cortisol, due to the body’s response to this fight or flight stress. Since one's body is reacting in response to what it thinks is a threat, its physiological response is that it has just done work, such as running, and in turn the cortisol hormone sends signals to refuel the body. This signal is an increase in appetite. This is where we see the effect of weight gain. When the body is under stress the cortisol levels increase, which in turn causes an increase in appetite and people tend to over eat. People tend to take in more calories than their body is really burning.
The Body Craves Foods High in Carbs and Fats
The body and the brain have an increase in appetite and tend to crave foods that are high in carbohydrates and fats. Just as after a person gets done running three miles their body tends to crave foods higher in carbohydrates and fats. That is due to the body using and burning those two substrates in response to such activities. When the body is under stress it reacts in the same way of exercising, the heart rate increases, blood pressure increases, and adrenaline increase. The body now reacts to these physiological responses in the same way it would to exercise.
The body and all of its glands and functions work to maintain homeostasis. When there is an upset in the balance of any of these functions we see adverse affects. When we look at the hormone cortisol, though it does not directly cause weight gain except when seen in Cushing’s disease, it does cause an increase in appetite and the body craves food high in carbohydrates and fats. These two effects do directly cause weight gain. Not only do they cause weight gain, but they also cause the body to gain weight in specific places, such as the abdomen. Gaining fat in the abdomen has been shown to have a correlation with a number of health ailments. This trickled down effect starts with the body’s reaction to stress and release of cortisol.
Although cortisol is not what creates the fat and weight gain, it is directly related to why the body gains weight and where the body gains weight. All hormones in the body play a role in maintaining and regulating all of the body’s functions. When just one hormone in the body is either too high or too low the body will be affected in some way.
