Another link between stress and chronic disease has been found in a small, observational study from Deakin University in Australia.
Overweight and obese men secrete higher levels of the stress hormone cortisol in their bodies after eating, which could make them more susceptible to developing chronic diseases, according to the research. The results of the study will be presented this Saturday at the The Endocrine Society's annual meeting in San Francisco.
Study participants included 19 men with a healthy body mass index between 20 and 25, and 17 overweight or obese men with a BMI of 27-35, all between the ages of 50 and 70. The subjects were all asked to prepare and consume a lunchtime meal with the same caloric content and the same amount of protein, fat and carbohydrates. Using a test called enzyme immunoassay, saliva samples were collected to test their cortisol levels 15 and 30 minutes before the men ate lunch, and then again every 15 minutes for 90 minutes after eating.
The overweight and obese men exhibited significantly higher cortisol levels after eating than the normal-weight men: While the men of healthy weight showed a 5 percent increase in salivary cortisol levels after consuming a meal, the cortisol levels of the overweight and obese men increased by 51 percent.
"This research indicates that when we are carrying excess fat stores, we may also be exposing our bodies to increased levels of the stress hormone cortisol every time we have a meal," the study's lead author Anne Turner, Ph.D., said in a statement. "If overweight and obese individuals have an increase in cortisol every time they ingest food, they may be at a greater risk of developing stress‐related diseases."
An extensive body of research has already begun to explore the links between stress and chronic diseases. Studies in the Netherlands found chronically high cortisol levels to be a risk factor in the development of cardiovascular disease, and a 2011 study found that chronic stress can lead to depression. Stress has also been found to help prostate cancer cells survive in the presence of anti-cancer drugs in mice -- but stress management could improve disease outcomes for breast cancer, according to University of Miami research.
"There is evidence that prolonged or chronic stress or exposure to the stress hormone cortisol is associated with greater incidence of chronic diseases such as cardiovascular disease, Type 2 diabetes and mental health problems such as anxiety and depression," Turner told the Huffington Post. "The concern is that frequent repeated exposure to short term or acute stress or elevations of cortisol may also lead to such diseases in the long term."
But the precise reasons why overweight individuals secrete so much more cortisol -- and how cortisol regulation occurs in the body -- are still poorly understood.
"It is thought that the fat cells themselves are somehow involved in regulating cortisol levels in the body but the exact mechanisms for how this occurs are not known," said Turner. "Further research is required to work out the exact reasons for this happening."