Intermittent energy restriction (IER), time-restricted eating (TRE) and continuous energy restriction (CER) are all dietary approaches that can improve blood glucose levels and support weight loss in people with type 2 diabetes and obesity, according to new research that was presented at ENDO 2025, the Endocrine Society's annual meeting.
However, while all three interventions effectively improved HbA1c levels, IER demonstrated greater advantages in reducing fasting blood glucose, improving insulin sensitivity, lowering triglycerides and enhancing adherence to the dietary approach.
"This study is the first to compare the effects of three different dietary interventions in managing type 2 diabetes with obesity," said lead author Haohao Zhang, Ph.D., chief physician at The First Affiliated Hospital of Zhengzhou University in Zhengzhou, China.
The 5:2 intermittent fasting method involves eating normally for five days and then restricting calorie intake to 500-600 calories on two non-consecutive days each week, while the 10 hour time-restricted eating requires individuals to consume all calories within a consistent 10-hour window. The third approach is more broad but requires a person to deliberately limit caloric intake, either by reducing the overall amount of food consumed or eliminating specific types of food.
While 5:2 intermittent fasting has shown promise as an effective strategy for controlling blood glucose levels and managing weight, data comparing it to other dietary approaches such as TRE and CER are limited. In this study, Dr. Zhang and colleagues sought to directly compare IER with TRE and CER in patients with obesity and type 2 diabetes.
They conducted a single-center, randomized, parallel-controlled trial that included 90 individuals who met the eligibility criteria. The cohort was randomized in a 1:1:1 ratio to the IER, TRE or CER group, with consistent weekly caloric intake across all groups. The 16-week intervention was conducted under the supervision of a team of nutritionists. The primary endpoint was the change in HbA1c levels, secondary endpoints included blood glucose, insulin sensitivity, blood lipids, uric acid, liver enzymes, safety, and adherence to the interventions.
A total of 63 patients completed the full study (18 females, 45 males, average age 36.8 years, average disease duration 1.5 years, baseline body mass index 31.7 kg/m², HbA1c 7.42%) and were included in the final analysis. Results showed that there were no significant differences between the IER, TRE and CER groups in lowering HbA1c (-1.56% vs -1.44% vs -1.03%, P = 0.23) and weight loss (-8.6 kg vs -8.2 kg vs -5.7 kg, P= 0.39). However, the absolute decrease in both HbA1c and body weight most pronounced among patients in the IER group.
Additionally, IER IER significantly lowered fasting blood glucose (-2.3 mmol/L [SD 1.51 mmol/L]) and triglycerides (-1.139 mmol/L [SD 1.335 mmol/L]) and raised the Matsuda index (80.23 [SD 70.69]) (all pairwise comparisons P < 0.05), as compared with the other two intervention groups. Reduction of uric acid and liver enzymes from baseline was similar among the three groups, and hypoglycemic evens were also similar (2 patients in the IER and TRE groups and 3 in the CER group).
Adherence to the dietary intervention was highest adherence in the IER group (85%), followed by the CER group at 84% and the TRE group at 78%, and this reached statistical significance (IER and CER groups versus the TRE group; P<0.05).
“The research fills a gap in directly comparing 5:2 intermittent energy restriction with a 10-hour time-restricted eating in patients with obesity and type 2 diabetes,” said Dr. Zhang. “The findings provide scientific evidence for clinicians to choose appropriate dietary strategies when treating such patients.”
Intermittent versus Time-Restricted or Continuous Calorie Restriction for the Management of Obesity with Type 2 Diabetes: A Randomized clinical Trial. Abstract OR19-08. Presented July 13, 2025. ENDO 2025, the annual meeting of The Endocrine Society
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