Patients with type 2 diabetes and obesity who were randomized to time-restricted eating (TRE; eating 12 to 8 p.m. only) lost more weight than those on a 25% calorie restriction (CR) diet, a small trial found. A total of 75 participants (mean body mass index of 39 kg/m2 and mean HbA1c level of 8.1%) were enrolled in the trial, which also included a control group. The study authors concluded that TRE without calorie counting was effective for weight loss and lowering of HbA1c level in patients with type 2 diabetes compared with daily calorie counting.
The study was published by JAMA Network Open on Oct. 27, 2023. The following commentary by Joseph M. Pappachan, MD, was published in the ACP Journal Club section of Annals of Internal Medicine on Feb. 6.
Dietary interventions such as TRE and CR are associated with weight reduction and glycemic control in patients with T2DM, although it is unclear which intervention is superior. Both interventions reduce weight by creating a total energy deficit and improve adipocyte function by reducing insulin resistance and improving T2DM. TRE is associated with improvements in blood pressure, lipid abnormalities, adipokines, and inflammatory cytokines, making this intervention an attractive option to improve cardiovascular health in patients with T2DM and obesity.
The trial by Pavlou and colleagues found that both TRE and CR reduced HbA1c by similar amounts (0.72% and 0.75%, respectively) vs. the control group. However, TRE reduced body weight and fat mass more than a control with no intervention and CR did not, making TRE a more attractive dietary intervention and corroborating the results of the CALERIE trial.
The trial was adequately powered to assess meaningful end points and inform clinical practice decisions despite its small sample size and relatively short follow-up for a randomized controlled trial examining common and lifelong health issues like obesity and T2DM. The greater weight loss in the TRE group vs. the CR and control groups may be due to greater calorie deficit in the TRE group vs. the CR and control groups and better adherence (87% vs. 68% of days) in the TRE group vs. the CR group. In addition, TRE in an 8-hour window is associated with depletion of liver glycogen stores by 12 hours and better mobilization of total body fat depots in the remaining 4 hours of fasting, which possibly explains better weight loss and metabolic benefits in this intervention group. Better adaptability and structuring of lifestyle by patients over time might explain higher adherence to intervention in the TRE group vs. the CR group.
Larger trials with longer follow-up should be done to confirm the possible superiority of TRE compared with the current practice of CR as standard dietary treatment for obesity in patients with T2DM.