Weight gain:
In order to control our metabolism, hunger and feelings of satiety our body releases a hormone called Leptin. Leptin is produced in fat cells and travels to the brain when we eat, which signals the brain that there is no need to eat any more because we have eaten enough and there is enough stored energy. When the leptin in your blood rises to a certain level your metabolism also increases.
Continual high levels of cortisol (this can be from physical, emotional or environmental stress) raise the leptin levels in the blood stream. Just like continual high levels of sugar in the blood can lead to insulin resistance and then diabetes, continual high levels of leptin can lead to leptin resistance. The brain becomes resistant to the leptin and in turn does not receive the signal to increase our metabolism and stop eating. This of course leads to overeating and weight gain.
Another hormone called adiponectin also suppresses the appetite and increases metabolism and levels of this hormone are decreased when cortisol levels are high.
Another way that stress can lead to weight gain is by the fact that cortisol stimulates the release of glucose into the blood stream, so when people are stressed, the foods they crave are sugar and refined carbohydrates because these are quickly converted to glucose. It is also difficult to maintain healthy eating habits when under stress. Comfort food and quick and easy meals are what most people tend to reach for.
Studies have shown that elevated cortisol levels cause fat to be deposited in the abdominal region which is the most dangerous area of the body to store fat. There are definite links between abdominal fat and a higher risk of cardiovascular disease.
Osteoporosis:
It is a difficult concept to understand how stress can impact on bones, but there is a lot of research to prove the connection.
Bones are being constantly remodelled. Bone cells called osteoblasts build bones and osteoclasts break down old and decaying bone. This is a constant, ongoing process which needs to remain in balance to retain strong, healthy bones.
High cortisol levels through stress inhibit osteoblast formation which drastically decreases the bone density. At the same time, the cortisol stimulates the osteoclasts which are the cells that break down bone.
A 2003 study reported in the journal Rheumatology that glucocorticoids (cortisol) “… have important actions on skeletal tissue that eventually lead to the development of osteoporosis.”
In 2006 the Annals of the New York Academy of Sciences reported “The most significant effect of glucocorticoids in bone is an inhibition of bone formation. This is because of a decrease in the number of osteoblasts and their function.”
As mentioned in Part 3 of this series, cortisol stimulates the release of glucose into the blood stream as part of the “fight or flight” response. One of the ways the body releases the glucose is through breaking down amino acids and one of the areas that the body steals the amino acids from is collagen, found in joints and bone.
Healthy weight and healthy bones – 2 more reasons why it is so important to manage your stress levels.
The final part to this series will be investigating the link between stress and adrenal and hormonal health.
By Andrea Southern, Naturopath, Clinical Nutritionist, Herbalist.
References:
http://www.naturalnews.com/033895_cortisol_bone_loss.html
http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2002.tb04204.x/abstract