Background

Time-restricted feeding (TRF) is a type of intermittent fasting regimen in which calories are consumed during a limited time period each day.

Methods

Qualitative semi-structured individual interviews were conducted with adults that completed a four-week cross-over design study of TRF. Participants were randomized to two weeks of a control condition and then two weeks of TRF or vice versa. In the TRF phase, participants restricted intake to a 12-hour time frame during which they ate ad libitum. Interview questions inquired about the experience of TRF, along with facilitators and barriers to compliance. Interviews were analyzed using the rapid analysis process to identify themes within each of the domains. Eating behavior related results are presented.

Results

Of the 21 participants, the mean age was 47 years (SE +/-2.5), 80% were female and 87% white. Average weight change during the two-week TRF phase was -1.3 lbs (SE +/-0.02). Dietary strategies to facilitate adherence to the TRF regimen included substituting calorie-free beverages for food during fasting, not eating evening snacks, redistributing meals and snacks to fit the feeding period, choosing convenience foods, planning meals and snacks, eating larger evening meals, and eating until satiated at the end of the feeding period. Eating related challenges included physical hunger during fasting, urgency and rapidity of eating within the feeding period, eating based on time restriction versus hunger cues, and overeating during the feeding period. The overall experience of TRF varied from enjoyable to stressful.

Conclusions

Participants in a study of TRF reported a variety of eating adaptations to accommodate a 12-hour TRF regimen. Some adaptations were consistent with disordered eating, including overeating, eating when not physiologically hungry and eating rapidly. Our results suggest that for some individuals TRF is not appropriate as it can promote unhealthy eating behaviors.