Early versus late time‐restricted feeding in adults at increased risk of developing type 2 diabetes: Is there an optimal time to eat for metabolic health?

Abstract Time‐restricted feeding (TRF) is a novel dietary approach where energy intake is limited to a set number of hours in the day (typically ≤12 hours), which leads to an extension of the daily fast that generally occurs overnight. Human pilot studies (based on animal experiments) have demonstrated that TRF has the potential to reduce risk factors for type 2 diabetes (T2DM): mediating weight loss, the reduction of low‐density lipoprotein (LDL) cholesterol and improving insulin sensitivity. However, it remains unclear whether it is better to restrict food intake to earlier in the day (early‐TRF) or later in the day (late‐TRF). The aim of this study is to investigate the effects of TRF on established risk factors for T2DM and its application to wider society. The primary hypothesis is that 10 weeks of daily TRF will reduce food intake, bodyweight and adiposity while improving markers of metabolic disease risk, such as LDL‐cholesterol and insulin sensitivity. The secondary hypothesis is that early‐TRF will induce larger metabolic changes in comparison to late‐TRF. Eligible volunteers will be randomised to either the early‐TRF (7 am to 3 pm), late‐TRF (12 pm to 8 pm) or control group (unrestricted eating window) for 10 weeks. Changes in fasting markers, diet, bodyweight and body composition will be assessed throughout the experiment, as well as the effects on psychological wellbeing and social and family interactions.