The Effect Of Time-Restricted Eating Protocols And Support On Women’s Cardiometabolic Health

PURPOSE: Time-restricted eating (TRE), a form of intermittent fasting that involves ad libitum eating within a pre-determined time window followed by water-only fasting, has been shown to improve numerous cardiometabolic risk factors (hemoglobin A1c (HbA1c), blood pressure, etc). While a common protocol is an 8-hour eating window (e.g., 11 am-7 pm), accounting for personal preferences such as duration and timing may reduce barriers to adherence but may be less effective. The objective of our study was to assess whether the type of TRE protocol (standard 11 am-7 pm or personalized time/duration) or type of support (provided externally by study staff vs by a peer in the study) impacts the effectiveness of TRE among women with or at risk for metabolic disease. METHODS: 178 women aged 50+ with type 2 diabetes, prediabetes, or moderate-high risk for diabetes were recruited across Ontario, Canada and randomized to one of five groups: control (usual dietary habits), standard-external, standard-peer, personalized-external, personalized-peer. The standardized protocol was a fixed eating window of 11 am-7 pm, while the personalized protocol group could modify their fasting length (14-16 h) and eating window start time. The peer support group was matched to another participant following the same TRE protocol, while the external group received support from a registered dietitian. A generalized linear mixed model was undertaken with a random effect for participant, fixed effects for time and group, and time*group interaction with adjustment for ethnicity, education, diabetes status, menopausal status, and waist circumference. RESULTS: 178 participants were enrolled and randomized (mean age 59.3 ± 5.9y, HbA1c 5.9 ± 0.6%). There were no group differences in HbA1c, blood pressure, c-reactive protein, waist circumference, Framingham risk score, homeostatic model assessment for insulin resistance, or metabolic syndrome z-score (time*group p > 0.05 for all). However, HbA1c (-0.05 ± 0.02%), diastolic blood pressure (-1.2 ± 0.5 mmHg), metabolic syndrome z-score (-0.4 ± 0.0.5) and waist circumference (-2.6 ± 0.3 cm) all decreased regardless of group (p < 0.05 for all). CONCLUSIONS: TRE protocol or support type did not influence changes in HbA1c or other cardiometabolic risk factors. CCS and CIHR