A Pavlovian Intervention to Condition Comforting Effects of Fruits

Perceived stress, lower fruit intake, and comfort eating are all risk factors for chronic disease. The present pilot study aimed to simultaneously mitigate all three risk factors by applying Pavlovian conditioning to change the nature of comfort eating. Specifically, stressed participants underwent a Pavlovian conditioning intervention designed to elicit comforting effects of fruit intake and thereby reduce negative mood while promoting fruit intake.

We developed a seven-dose Pavlovian conditioning intervention wherein participants temporally paired together Progressive Muscle Relaxation (unconditioned stimulus) with fruit intake (conditioned stimulus) daily for 1 week. Participants (N = 100, mean [standard deviation] age = 20.7 [4.6] years; 74% female) with moderate to high levels of baseline perceived stress were randomized to the intervention or an active explicitly unpaired control group, wherein the Progressive Muscle Relaxation and fruit intake also occurred but were not temporally paired together. After the intervention, participants' negative mood was assessed immediately before and after fruit intake to assess conditioning effects. Then, participants logged their regular food intake for 4 days using the MyFitnessPal smartphone app.

After the intervention, fruit intake acutely improved negative mood to a greater extent among the intervention versus control group (F(1,98) = 3.99, p = .048, = 0.039). However, there was not a significant between-group difference in intake of fruit or traditional comfort foods at postintervention.

Repeated pairing of fruit intake with a reliable distress-reducing activity led to the conditioning of comforting effects of fruit intake. Further refinement of the intervention design is necessary to translate this conditioned association to actual intake of fruit and other foods.