Abstract
Background: Obesity is a significant health issue in Aotearoa, New Zealand. Effective and pragmatic strategies to facilitate weight loss are urgently required. Growing recognition of the impact that the circadian rhythm has on metabolism has popularised diets like time-restricted eating (TRE). The 16:8 TRE method involves limiting food intake to an 8-hour daily eating window and can lead to weight loss without other substantial changes to diet. Nonetheless, TRE requires accountability and tolerating hunger for short periods. Continuous glucose monitoring (CGM) devices are small wearable biofeedback sensors that measure interstitial glucose levels and are scanned with smartphones. By providing immediate feedback on the physiological effects of eating and fasting, CGM use may promote adherence to TRE.
Methods: This pilot study aimed to 1) investigate how CGM affects adherence to TRE, and 2) assess the feasibility of CGM use while undertaking TRE. This two-arm randomised controlled trial recruited healthy adults from Ĺtepoti, Dunedin, in Aotearoa, New Zealand. Participants were assigned to TRE+CGM or TRE-only groups for 14 days. Successful adherence to TRE was defined a priori as maintaining an 8-hour eating window on 80% of days. CGM feasibility was defined a priori as scanning the glucose sensor thrice daily on 80% of days. Secondary outcomes included well-being; anthropometry; glucose levels; and qualitative data were collected on overall TRE and CGM experiences via semi-structured interviews.
Results: Twenty-two participants were randomised into two groups: TRE+CGM (n=11) and TRE-only (n=11). Two participants in the TRE+CGM group were subsequently excluded post-randomisation for previously undisclosed medical reasons. Participants had a range of ethnicities; the mean age was 32 years (SD 14.9 years), and 55% were female. The TRE+CGM group adhered to the 8-hour eating window for a mean number of 10.0 days (SD 4.0 days) compared with 8.6 days (SD 4.2 days) in the TRE-only group. Both groups had similar mean eating window durations of 8.0 hours (SD 1.8 hours) in the TRE+CGM group and 8.1 hours (SD 1.6 hours) in the TRE-only group. Five participants in the TRE+CGM group achieved the a priori criterion for TRE adherence, compared to 3 in the TRE-only group. Participants in the TRE+CGM group performed an average of 8.2 daily scans (SD 5.6 daily scans) daily scans, with seven participants meeting the a priori CGM feasibility criterion. Neither group reported consistent adverse psychological effects in DASS-21 and WHO-5 scores. Interviews highlighted the positive and negative aspects of TRE, and the influence that CGM use had on TRE practice. Positive aspects of TRE included increased awareness of eating habits, improved self-efficacy, and more efficient daily routines. Negative aspects of TRE included scheduling issues, difficulties in social situations, and adverse physical and psychological effects. Participants reported that CGM increased hunger tolerance, aided TRE adherence and accountability, and made practising TRE more interesting. Promisingly, most participants would use CGM and undertake TRE in future.
Conclusions: This study demonstrates that using CGM while undertaking TRE is feasible and may improve adherence to TRE. Overall, participants experienced an increased awareness of their eating habits and glucose levels. Over the longer term, this simple and synergistic approach may be a helpful weight loss strategy. Larger scale trials should continue to explore the influence of CGM use on enhancing TRE adherence.