Thursday, May 17, 2007
Tuesday, May 08, 2007
Dallman MF, Pecoraro N, et al. (2003) Chronic stress and obesity: a new view of "comfort food". Proceedings of the National Academy of Sciences Sep 30; 100(20): 11696-701.
The body reacts to stress by releasing catecholamines and glucocorticoids (GCs), hormones that control a major part of the autonomic nervous system. The Hypothalamic-Pituitary-Adrenal (HPA) axis is also a major aspect of this system, since its primary role is to balance the stress hormones mentioned above. This study's main objective was to observe how chronic stress plays a role in obesity, particularly in how chronically high levels of GCs act in three ways to cause the individual to rely upon "comfort foods," which are higher in refined carbohydrate and saturated fat. Those three ways include: one, high amounts of CRF in the amygdala; two, high stimulus salience of activities; and three, high abdominal obesity, which lowers HPA activity.
Although this study used rats as its main subjects to analyze the above three ways, the authors state that the effects of chronic stress and GCs in rats do indeed apply to humans, as well. In the first way, GCs will increase the expression of CRF (corticotropin-releasing factor) in the amygdala (the node in the emotional part of the brain). The high expression of CRF induces us to draw from "the chronic stress network" pool, which increases ACTH and corticosterone B, both hormones that respond to acute stressors and increase anxiety-like behavior. In addition, recruiting this chronic stress network over time will increase the PVT (paraventricular thalamus) secretion of glutamate, which is said to increase synaptic connections. My postulation is that drawing from the chronic stress network pool over time will deplete the components necessary to confront stressful situations, which in turn, can cause compulsive activity since the response network won't be as efficient.
The second way that chronic GC affects our bodies is via a high stimulus salience of activities, which includes exactly what I postulated—namely compulsive activity. This study defined compulsive activity as ingesting sucrose, fat, drugs and wheel-running. They found that corticosterone B specifically raised consumption of comfort foods when rats were chronically stressed, which is again, due to high GCs causing an excitatory response in the brain. With comfort food, HPA axis activity declines, meaning that the ability for the body to balance its stress hormones is greatly reduced. As a result, to lead into the third way that was mentioned, the body responds with a build-up of abdominal fat depots, which increases the inhibitory feedback signal of CRF. Since CRF receptors lie in the amygdala, this emotional cycle can continue and lead to obesity if stress levels are left unchecked.
What is essential to note is the decrease in HPA axis activity, since we decrease the ability to balance our GCs and catecholamines. In turn, the inability to balance these hormones properly can impel one to look to outside mechanisms, such as the comfort foods, the drugs, etc, to regulate the internal chaos. Ironically, eating these foods and/or doing drugs only worsens the havoc within the body, and the cycle continues. The study's authors suggest that attempting to reduce stress in one's life can help to mitigate the effects of our chronic stress-response network, and can help to improve overall mental and physical health.
Posted by Marissa Beck at 12:31 PM
Sunday, May 06, 2007
My mother sent me the following:
I was walking down the street when I was accosted by a particularly dirty and shabby-looking homeless woman who asked me for a couple of dollars for dinner. I took out my wallet, got out ten dollars and asked, "If I give you this money, will you buy some wine with it instead of dinner?"
"No, I had to stop drinking years ago", the homeless woman told me.
"Will you use it to go shopping instead of buying food?" I asked.
"No, I don't waste time shopping," the homeless woman said. "I need to spend all my time trying to stay alive."
"Will you spend this on a beauty salon instead of food?" I asked.
"Are you NUTS!" replied the homeless woman. "I haven't had my hair done in 20 years!"
"Well," I said, "I'm not going to give you the money. Instead, I'm going to take you out for dinner with my husband and me tonight."
The homeless woman was shocked. "Won't your husband be furious with you for doing that? I know I'm dirty, and I probably smell pretty disgusting."
I said, "That's okay. It's important for him to see what a woman looks like after she has given up shopping, hair appointments, and wine."
Posted by Marissa Beck at 12:44 PM
Friday, May 04, 2007
Wednesday, May 02, 2007
He sat next to me for a whole two hours, at which point he whips out the mother-load of zip-locks, chock-full of nutty trail mix. He left it in his bag for two hours without touching it once. If I had a zip-lock of mix in my bag, that would be like the alcoholic trying to remain sober with a wine bottle in the fridge. Yet, while I can keep my wine chilled for weeks, the alchie can keep trail mix in his book-bag without the slightest urge to ravage. And therein lies the whole nutty truth :)
Posted by Marissa Beck at 12:02 AM
My personal blog here at Blogger is still going to remain intact; however, please visit my new website, http://marissabeck.wordpress.com, which will host more nutrition topics (because obviously you just can't get enough!)