European Primary Care Cardiovascular Society

Intermittent fasting plus early time-restricted eating in adults at risk of T2DM

Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial

Literature - Tong Teong X, Liu K, Vincent AD, et al. - Nat Med. 2023 Apr;29(4):963-972. doi: 10.1038/s41591-023-02287-7

Introduction and methods


Healthy lifestyle changes such as dietary interventions and weight management reduce the risk of developing T2DM [1-2]. Intermittent fasting (IF), which is often described as days with ~30% of energy requirements interspersed with days of unrestricted eating, results in greater improvements in insulin resistance compared with calorie restriction (CR) [3-4]. However, it remains unknown whether IF improves postprandial glucose tolerance compared with CR. Time-restricted eating (TRE) with long fasting periods per day has emerged as a novel IF method, which is more in alignment with circadian rhythms, and may active several metabolic pathways [5-6].

Aim of the study

The authors compared the effects of IF plus early time-restricted eating (iTRE) with CR and standard care in adults at risk of T2DM.



This was an open-label, three-arm parallel group sequential RCT, with a 6-month intervention phase followed by a 12-month follow-up. A total of 209 participants (57% female, 58±10 years, 34.8 ± 4.7 kg mֿ²) were randomized to iTRE, CR or standard care (2:2:1 ratio). iTRE was defined as 30% of energy requirements consumed between 8:00 and 12:00, followed by a 20-h fasting period on three nonconsecutive days per week and unrestricted eating on other days. CR was defined as 70% of the energy requirements without time prescription. Participants in the iTRE group and CR group received meal replacements and one-on-one diet counseling during the first 6 months. After 6 months these participants had the option to continue with the previous or a modified plan. Participants in the standard care group received a weight booklet, with no further counseling. Eligible participants were aged 35-75 years, scored ≥12 on the Australian Type 2 Diabetes Risk Assessment Tool, had weight fluctuations ≤5% for more than 6 months before study entry, had no diagnosis of diabetes, and did not take medications that might affect glucose metabolism and/or weight management.


The primary endpoint was the change in postprandial glucose area under the curve (AUC) at 6 months. Key secondary endpoints were related to changes in glycemic, cardiovascular and liver markers, and body weight.

Main results

Glycemic control

Cardiovascular risk

Liver health

Body weight and composition

Safety outcomes


iTRE led to greater improvements in postprandial glucose metabolism at month 6 in adults at increased risk of T2DM compared to CR or standard care. Fasting triglycerides were strongly reduced at month 2 and 6 in the iTRE group, but not in the CR or the standard care group. Weight loss was greater in the iTRE and CR group compared to the standard care group, but these reductions were lost at follow-up. This indicates that neither weight loss plans were sustainable without active counseling.


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