Low Back Pain Reduces Enjoyment of Food
People with chronic low back pain appear to lose their enjoyment of eating, resulting in a blunting of feelings of satisfaction, satiety, and pleasure. This can lead to a cycle of over-eating and weight gain, which than contribute to continued low back pain. Innovative new research is now examining how pain influences eating behaviors that led to obesity.
In the latest issue of Pain, Paul Geha, MD, a researcher at Yale University’s School of Medicine in New Haven, Connecticut, and his team tried to examine how patients suffering from chronic low back pain (CLBP) received a lesser degree of pleasure from eating fatty foods.1
Their research suggests that chronic pain may cause hedonic blunting for patients. This describes an acute decrease in the proper functioning of the neurological mechanisms in the brain that induce pleasure.
By studying how CLBP patients reacted to eating fatty puddings compared to a healthy control group, they Yale group found that the CLBP group reported significantly lower pleasure ratings from eating the fatty puddings. While the healthy group tended to eat pudding until they felt satisfied with pleasure and their hunger was satiated, CLBP patients’ caloric intake seemed completely disconnected to how much they enjoyed the pudding.
In other words, pleasure from eating was blunted in such a way that caloric consumption could be much higher, a sign suggesting that chronic pain may induce overeating, which could lead to obesity.
Other researchers have noted that these patients may have neurological deficiencies that are preventing them from experiencing the natural pleasures associated with eating. In a commentary, Siri Graff Leknes, a researcher at the University of Oslo in Norway, and Brock Bastian of the University of New South Wales in Australia, discussed how the “decoupling effect” of CLBP patients’ food pleasure and caloric intakes could be explained by an opioid signaling problem in the ventral stratium and medial prefrontal cortex areas of the brain, neurological centers associated with experiencing food pleasure.2
While Leknes and Bastian suggest this could help explain why pain and obesity are so related, they stressed there’s still much more research to be done and other theories to consider.
Depression and Overeating
Another research study suggests that pain patients’ anhedonia, or lack of ability to experience pleasure, was more related to their depression than the pain they were experiencing, Bastian and Leknes said.3 Last year, Dr. Bastian and his fellow researchers published a paper in Appetite that examined how the offset of pain could actually increase gustatory pleasure. They found through multiple tastes that pain offset not only increased the hedonic rewards from tasty foods but actually increased the overall sensitivity of gustatory input, which allowed subjects to better enjoy pleasant tastes and also perceive a wider range of other flavors and taste sensations.4
Other theories exist that focus more on the psychological responses and triggers to eating, such as the consuming of food when under emotional turmoil regardless of appetite—commonly referred to as emotional eating.5 One study looked at how patients experiencing chronic pain could have a higher sense of entitlement because of their suffering and, therefore, would eat more sweets.6
Such layers of complexity present a topic in pain research that should be further explored, Leknes and Bastian said. When asked whether multiple factors—neurological, psychological, or otherwise—could influence each other to further imbalance caloric consumption, Dr. Bastian said that such factors probably don’t influence each other.
“I do think they could be additive,” Dr. Bastian said, “This doesn’t mean one causes or shapes the other, but together they contribute to greater obesity.”
As to why food pleasure and pain have yet to be more thoroughly researched, the idea of pain has been more examined as related to injuries and illnesses rather than subjective experiences like enjoying food, Dr. Bastian said.
Because the subjective sensations of pain and pleasure cannot be easily relegated as experiences completely opposite or unconnected from each other, Leknes and Bastian believe that looking at eating and pain could be “a fruitful area for future research.”2