During times of stress, I often find myself reaching for comfort foods — a tempting Oreo, some chips, a homemade cookie, and occasionally a bowl of chicken soup. However, therein lies a problem, particularly for those advocating for more nutritious comfort options. Many of these go-to foods, chosen in response to day-to-day stressors, are rich in palate pleasers, fat, sugar, and a bit of salt, contributing to our expanding waistlines and a growing mismatch with our metabolism.
New research published in Psychosomatic Medicine asks whether our comfort foods might shift to more nutritious choices, say fruit, which offers its own delights when we are appropriately “retrained.”
“This intervention is the first of its kind to apply longstanding Pavlovian conditioning principles to the context of comfort eating. … we hypothesized that after repeatedly pairing together fruit intake with a reliable distress-reducing activity, that fruit intake alone would elicit psychological distress relief.”
Healthy undergraduates, the white rats of psychology departments, were chosen as study subjects. They were asked to rate 20 fruits they had previously tasted, and one was selected that was “neutral” in terms of pleasantness and a bit “novel,” i.e., pomegranates [1] as their fruit stimulus. For fans of Pavlov, the fruit is the bell.
“Distress reduction” was induced using the technique of progressive muscle relaxation (PMR), where specific muscle groups are first tensed and then relaxed, beginning at the head or foot and advancing up or down. All participants reported diminished tenseness and stress and enhanced relaxation and calmness after six minutes of PMR. For those inclined towards physiology, there was also a slight reduction in heart rate. In Pavlovian terms, PMR became the food, altering negative mood instead of inducing salivation.
The intervention group underwent pairing of fruit and PMR daily for a week, and the control group also experienced fruit and PMR over a week, but they were not paired in time. For the intervention group, five minutes after beginning PMR, “a tone cued participants to begin consuming their fruit.”
The subjective experience of a “negative mood,” in the words of the researchers, “significantly decreased” in both groups, but more in the intervention group pairing fruit with stress reduction – “fruit mood conditioned response.” Additionally, when those in the intervention group who “expressed dissatisfaction” with their fruit were removed, the effect of the intervention was even greater.
However, Pavlovian principles didn't carry over to the rest of the day. Both groups continued to consume their traditional comfort foods. While the silver lining was that they also ate the fruit introduced during the study, it highlighted that our desire for comfort food goes beyond a Pavlovian or operant response.
“The intervention improved the comforting effects of fruit intake relative to the rigorous control group, and thus represents a promising strategy for negative mood improvement.”
The study design is flawed. There was no initial stressor. More significantly, the study was conducted in a laboratory, not under real-world conditions. I do not doubt that part of why I reach for comfort food is Pavlovian – but the comfort in comfort foods lies in more than their taste or any dopamine release we might posit. It has to do with who provided that comfort and under what conditions. The cookie or cake was provided by someone who cared for me in multiple ways, perhaps a soothing tone or a cuddle and hug. Harlow’s experiments on the nurturing effect of cloth vs. wire surrogate mothers for monkeys are eloquent examples of why a purely Pavlovian approach to our diet will not work.
Eating serves more purposes than meeting a physiological need, especially for social creatures. As the Dutch scientist Louise Fresco, studying sustainable foods, aptly puts it,
“Food, in the end, in our own tradition, is something holy. It's not about nutrients and calories. It's about sharing. It's about honesty. It's about identity.”
[1] Other fruits include apples, bananas, blueberries, honeydew, pears, pineapples, oranges, grapes, clementines, apricots, strawberries, mangos, and kiwis. I would add parenthetically that grapes are one of my go-to comfort foods, but only after fermentation.
Source: A Pavlovian Intervention to Condition Comforting Effects of Fruits Psychosomatic Medicine DOI: 10.1097/PSY.0000000000001008
Chuck Dinerstein, MD, MBA
Director of Medicine
Dr. Charles Dinerstein, M.D., MBA, FACS is Director of Medicine at the American Council on Science and Health. He has over 25 years of experience as a vascular surgeon.
