(P30-031-24) Time-Restricted Eating: Microbiome, Metabolic Health, and Bone (TREMBO) Study Protocol

Objectives: The majority of Americans are overweight or obese and eat over ≥ 12 hours a day. Calorie restriction (CR) causes weight loss (WL) and improves obesity-related outcomes, however, WL in older adults negatively affects bone. In addition, eating for ≥ 12 hours can disrupt the circadian rhythm. Circadian disruption is correlated with weight gain, gut dysbiosis, and osteoporosis. Time-restricted eating (TRE) can restore circadian synchronicity and may positively affect health outcomes. To date, no TRE studies have been designed to examine bone as a primary outcome. To address this gap, we will examine the effect of six months of CR with or without TRE on bone, markers of cardiometabolic health, and the gut microbiota in older women..

Methods: The TREMBO trial randomized women (body mass index, BMI, ≥ 25 kg/m², 50-79 years old) to six months of CR with or without TRE. Participants are assigned to CR and asked to attend 12 sessions with a registered dietitian. Those assigned to CR+TRE are instructed to self-select a ≤ 9-hour eating window. The CR alone group is asked to follow their usual eating window without skipping meals and to have an evening snack. Bone mineral density and bone quality are assessed by dual-energy x-ray absorptiometry and peripheral quantitative computed tomography at weeks 0 and 24. Glucose and insulin are assessed via a 2-hour 75g oral glucose tolerance test and cardiometabolic markers that will be assessed at weeks 0 and 24. Bone metabolism markers, circadian markers, and the gut microbiota will be measured at weeks 0, 12, and 24.

Results: In TREMBO, 168 participants were screened and 49 were eligible and enrolled. The women are older (61 ± 5 years), predominantly white (71%), and have a BMI of 33 ± 2 kg/m² (47% fat mass). At baseline, participants had a fasting glucose of 97 ± 9 mg/dL with an eating window of 12.3 ± 0.8 hours/day. Bone mineral density at the lumbar spine and hip are 1.23 ± 0.2 and 0.99 ± 0.1 g/cm², respectively. Data collection is ongoing for this study.

Conclusions: Results from the TREMBO trial will be the first time-restricted eating study to determine the circadian effect of food intake on bone as a primary outcome. Determining effective weight loss protocols that minimize concomitant loss of bone in older women is an important focus area in the aging field.

Funding Sources: NJ-IFNH Seed Grant; USDA-NIFA