Why people with chronic pain are prone to obesity

On 29 May 2004, two British women walked past the door of a fast food restaurant in London. (Photo by Xinhua reporter Cheng Min)

BEIJING, Feb. 13 (Xinhua) -- Some chronic pain sufferers often struggle with their weight. A study recently published in the journal Science Public Library General found an explanation for this phenomenon, that is, when a person experiences pain, the areas of the brain responsible for pleasure are affected. This finding may shed light on the physiological mechanisms underlying chronic pain associated with changes in eating behavior that may lead to the development of obesity.

Finding pleasure in food comes from the brain's response to food. Researchers at institutions such as the University of Rochester and Yale University in the United States have observed how the brain responds to sugar and fat. The researchers changed the amount of sugar and fat in the pudding and made people with chronic pain eat. It was found that some patients with chronic pain did not experience a change in eating excess when they ingested sugar, but changed when they ingested fat.

People with chronic low back pain whose pain lasts for a year don't initially overeat, but over time, high-fat foods like ice cream and cookies become a problem. Brain scans show that after eating these foods, the signals of satiety transmitted from the digestive system to the brain are interrupted in patients with chronic low back pain. The nucleus accumbens plays an important role in the brain's reward, happiness, and other activities. Brain scans also showed that patients with chronic pain had smaller areas of the nucleus accumbens in their brains, suggesting that their pleasure was also affected. This may stimulate them to eat excessive amounts of high-fat foods for enough pleasure.

The researchers note that this study suggests that obesity in people with chronic pain may not be caused by lack of exercise, and that chronic pain may alter the amount they eat for high-fat foods, etc., leading to the development of obesity.