Researchers at the University of California, San Francisco have found a feedback system in rats that may explain the craving of so called “comfort foods” in people who are under stress. A steroid hormone, called corticosterone, is produced in rats as a response to stress. The human equivalent of this hormone is cortisol. It causes rats to engage in pleasure seeking behavior 24 hours after stress. This behavior causes the rats to crave high calorie food. In the rats’ case, the food was sugar and lard. The hormone’s effect on people is likely to make them crave chocolate or greasy burgers.

The research also explains why some people get abdominal obesity. Chronic stress caused the rats to gain weight around the abdomen. The fat cells actually work to curb the stress. The researchers suspect that the metabolic signal to inhibit the stress system comes directly from fat depots. The finding offers an explanation into how chronic stress can be inhibited, or curbed.

The body’s acute response to stress, like a single event like being cut off in traffic, diminishes through an inhibitory feedback mechanism of the adrenal stress system. Chronic stress, which is a series of negative events, worrying, frustration occurring over a period of weeks or months, does damage to the body. It creates depression, obesity, a tendency to type II diabetes, the metabolic syndrome (high cholesterol with high LDL, low HDL, high triglycerides and high blood pressure), cardiovascular problems and a loss of brain tissue.

“Our studies suggest that comfort food applies the brakes on a key element of chronic stress,” says study co-author Norman Pecoraro, PhD, “And it could explain, why solace is often sought in such foods by people with stress, anxiety or depression.” The mechanism may also explain bulimia and night time binge eating.

 

This may be part of a survival mechanism. In the animal kingdom, it’s eat or be eaten, and constant, or chronic, stress may make the animal prefer to eat high-energy foods for fuel to help with survival. Under the model that the research team has proposed, corticosterone (or in humans, cortisol) would prompt vigilance to threats and also send a signal to the brain of a chronically stressed animal to seek high-energy food. If it were successful in finding such food, stress and its attendant feelings would end.

 

If there is war, food shortage, disease, food shortage and other threats to survival, the need for high calorie food is great. In a society where people do not face these dire conditions, stress comes in the form of job deadlines, fights with the spouse, rush hour traffic, or financial worries. But the stressed out office worker seeks the same solution as the person or animal who’s survival is being threatened—food. The choice to eat chocolate or a greasy burger may well come from chronic stress.

 

In a society where people eat too much junk food and there is a problem with adult onset diabetes, obesity, and heart disease, we need a better way to address chronic stress. In a civilized society, overeating merely makes the physiologic problems of stress. Better solutions would be exercise, deep-breathing, yoga, meditation, or even a good hot bath. These can stimulate neurochemicals that activate regions of the brain that stimulate pleasure. Relaxation techniques may work by reducing the psychological drives on stress output, which can be the root causes of stress.