Effects of a health versus hedonic mindset on daily-life snacking behaviour.

BACKGROUND: In today's obesogenic environment high-caloric palatable foods are omnipresent, making it hard for many to reach and maintain a healthy body weight. This study investigates the effects of a health versus hedonic mindset on daily-life snacking behaviour. The hypothesis is that a health mindset leads to reduced snacking behaviour compared to a hedonic mindset. This effect is expected to be most pronounced with high dietary restraint and least pronounced with high trait self-control. METHODS: For 3 weeks, degree of craving and amount of snacks that were craved and consumed were assessed four times a day, using smartphone Ecological Momentary Assessment (EMA). A total of 111 female participants (body mass index range: 20-23.5) were randomly assigned to a 1-week health (n = 53) or hedonic (n = 58) mindset, occurring in week 2 of the EMA protocol. The mindset manipulations consisted of text messages, focusing either on the enjoyment of tasty food (hedonic) or on healthy living and eating (health). RESULTS: contrary to our hypotheses, mindset did not affect snacking behaviour. Instead, degree of craving and intake of snacks reduced significantly over time, not moderated by mindset, dietary restraint (Restraint Scale) or trait self-control (Brief Self-Control Scale). Importantly, this was not due to reduced compliance. Possibly, the reduced craving and snacking behaviour were due to monitoring and/or socially desirable answering tendencies. Additional time point analyses showed that craving was strongest in the late afternoon (3:30-5:00 PM), and-across mindset conditions-degree of craving correlated negatively with trait self-control. CONCLUSIONS: future studies could manipulate degree of monitoring and design individually tailored manipulations.

In vivo phase-dependent enhancement and suppression of human brain oscillations by transcranial alternating current stimulation (tACS).

Transcranial alternating current stimulation (tACS) can influence perception and behavior, with recent evidence also highlighting its potential impact in clinical settings, but its underlying mechanisms are poorly understood. Behavioral and indirect physiological evidence indicates that phase-dependent constructive and destructive interference between the applied electric field and brain oscillations at the stimulation frequency may play an important role, but in vivo validation during stimulation was unfeasible because stimulation artifacts impede single-trial assessment of brain oscillations during tACS. Here, we attenuated stimulation artifacts to provide evidence for phase-dependent enhancement and suppression of visually evoked steady state responses (SSR) during amplitude-modulated tACS (AM-tACS). We found that AM-tACS enhanced and suppressed SSR by 5.77 ± 2.95%, while it enhanced and suppressed corresponding visual perception by 7.99 ± 5.15%. While not designed to investigate the underlying mechanisms of this effect, our study suggests feasibility and superiority of phase-locked (closed-loop) AM-tACS over conventional (open-loop) AM-tACS to purposefully enhance or suppress brain oscillations at specific frequencies.