Food product health warnings promote dietary self-control through reductions in neural signals indexing food cue reactivity

Abstract

Modern societies are replete with palatable food cues. A growing body of evidence suggests that food cue exposure activates conditioned appetitive physiological and psychological responses that may override current metabolic needs and existing eating goals, such as the desire to maintain a healthy diet. This conditioned response results in unhealthy dietary choices and is a contributing factor in the current obesity epidemic. Prime based obesity prevention measures such as health warnings at point-of-sale or on product packaging may have the potential to counteract the influence of the obesogenic environment at the crucial moment when people make food purchasing or consumption decisions. Existing research into the efficacy of these intervention strategies has predominantly employed self-report and population level measures, and little evidence exists to support the contention that these measures counteract food cue reactivity at the time of decision making. Using a dietary self-control priming paradigm, we demonstrated that brief exposure to food product health warnings enhanced dietary self-control. Further, we analysed electroencephalographic correlates of selective attention and food cue evoked craving (N1, P3, LPP) to show that health warning exposure reduced the automatic appetitive response towards palatable food cues. These findings contribute to existing evidence that exogenous information can successfully prime latent goals, and substantiate the notion that food product health warnings may provide a new avenue through which to curb excessive energy intake and reduce rising obesity rates.

Keywords: Dietary decision making; EEG; Electroencephalogram; Health warnings; LPP; N1; P3; Self-control.

Fig. 1

Testing session procedure. (A) Participants completed an experimental task with four stages: the rating stage, the unprimed decision stage, the priming stage, and the primed decision stage. (B) One example rating stage trial. During this stage participants rated all food items on perceived health and taste. These ratings were used to allocate items to the unprimed and primed decision stages, ensuring that these stages featured a balanced set of stimuli. (C) One priming stage trial (health warning group, without attention check). Control group participants completed the same task during this stage, however they were shown scrambled health warning images. (D) One example decision stage trial. During these stages, participants chose items they would like to eat at the end of the experiment, while also indicating the strength of their choice. Participants completed the same task in unprimed and primed decision stage trials.

Fig. 2

Mean dietary self-control (measured as proportion of healthy-not tasty items chosen relative to unhealthy-tasty items chosen) in the unprimed and primed decision stages for health warning group and control group participants. Error bars denote standard error.

Fig. 3

Change in dietary choice response (positive values correspond with “yes” responses, negative values with “no” responses, to the question “Would you like to eat this food at the end of the experiment?”) between the unprimed and primed decision stages, as a function of stimulus health and taste attributes, for (A) control group participants, and (B) health warning group participants. In general, health warning group participants displayed an increased likelihood of choosing low taste and high health items and a decreased likelihood of choosing high taste and low health items after exposure to health warnings. Control group participants showed no clear systematic change in their dietary choices.

Fig. 4

Grand average waveforms of the N1 ERP (125–200 ms) at occipital electrode cluster (Oz, O2, O1 and Iz) for (A) control group participants and (B) health warning group participants. Orange lines denote trials featuring food items perceived as healthy, purple lines denote trials featuring food items perceived as unhealthy. Dotted lines denote unprimed decision stage trials and solid lines denote primed decision stage trials. Positive amplitudes plotted upwards.

Fig. 5

Grand average waveforms of the P3 (250–450 ms) and LPP (450–750 ms) ERPs at midline parietal electrodes (CPz, Pz and POz) for (A) control group participants during the unprimed decision stage, (B) control group participants during the primed decision stage, (C) health warning group participants during the unprimed decision stage, and (D) health warning group participants during the primed decision stage. Blue lines denote trials featuring food items perceived as tasty, red lines denote trials featuring food items perceived as not tasty. Positive amplitudes plotted upwards.