Intermittent Fasting, Calorie Restriction Deliver Similar Cardiometabolic Outcomes in T2D

Dietary modification is central to managing type 2 diabetes, but the optimal approach remains unclear. Continuous calorie restriction has long been the standard, with well-established benefits for glycemic control and weight loss. However, more recently, intermittent fasting strategies have gained popularity as potentially simpler alternatives that may offer similar metabolic benefits without daily calorie tracking.

Currently, there is a lack of direct comparisons between intermittent fasting and calorie restriction in patients with type 2 diabetes, and uncertainty remains around their relative effects on HbA1c, weight, and cardiometabolic risk, as well as safety considerations like hypoglycemia. To address this gap, Lyluma Ishfaq, MD, an internal medicine resident at Central Michigan University, and colleagues conducted a systematic review and meta-analysis, with findings presented at the American Association of Clinical Endocrinology (AACE) Annual Meeting 2026.

Seeking to compare the effects of intermittent fasting versus calorie restriction on glycemic control, weight, and cardiometabolic risk factors in adults with type 2 diabetes, investigators searched PubMed and ClinicalTrials.gov for randomized trials directly comparing both strategies for ≥12 weeks. They excluded nonrandomized studies, trials without a calorie restriction comparator, and trials in prediabetes or without type 2 diabetes-only data. Given that only 2 heterogeneous RCTs met the inclusion criteria, investigators opted to perform a descriptive quantitative synthesis rather than a single pooled estimate.

The first included study was a randomized noninferiority trial conducted at the University of South Australia in which adults with type 2 diabetes were randomized in a 1:1 ratio to parallel diet groups of intermittent energy restriction or continuous energy restriction. The second study was a 6-month randomized clinical trial conducted at the University of Illinois Chicago that enrolled adults with obesity and type 2 diabetes and randomized them to 1 of 3 groups: 8-hour time-restricted eating from 12pm to 8pm only, calorie restriction of 25% daily, or control.

Among 212 participants across both trials (n = 105 intermittent fasting; n = 107 calorie restriction), investigators noted HbA1c decreased similarly with both strategies. In the first study, 12-month HbA1c declined by −0.5% with calorie restriction and −0.3% with intermittent fasting, a between-group difference of 0.2% (90% CI, −0.2 to 0.5), meeting the prespecified equivalence criterion. In the second study, 6-month HbA1c changed by −0.72% with intermittent fasting, −0.75% with calorie restriction, and 0.19% with control, with no significant difference between intermittent fasting and calorie restriction (mean difference, 0.04%; 95% CI, −0.64 to 0.72).

Of note, weight loss slightly favored intermittent fasting (−6.8 vs −5.0 kg at 12 months in the first study; −4.3% vs −2.5% at 6 months in the second study), though these differences were not statistically significant. Fasting glucose, lipids, blood pressure, and hypoglycemia rates were additionally similar between groups.

“In adults with T2D, current randomized evidence suggests that IF achieves HbA1c reductions equivalent to daily calorie restriction, with a trend toward slightly greater weight loss but no consistent additional metabolic advantage. Both strategies appear safe when hypoglycemia-inducing medications are proactively adjusted,” ? and colleagues wrote. “Larger, longer RCTs are needed to define differential effects on long-term glycemic durability, cardiovascular outcomes, and patient-centered adherence.”

References

1. Ishfaq L, Khan A, Zargar MN, et al. Metabolic Outcomes of Intermittent Fasting Versus Continuous Calorie Restriction in Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Trials. Presented at the American Association of Clinical Endocrinology (AACE) Annual Meeting 2026 in Las Vegas, Nevada, April 22-24, 2026.

2. Carter S, Clifton PM, Keogh JB. Effect of Intermittent Compared With Continuous Energy Restricted Diet on Glycemic Control in Patients With Type 2 Diabetes: A Randomized Noninferiority Trial. JAMA Netw Open. 2018;1(3):e180756. doi:10.1001/jamanetworkopen.2018.0756

3. Pavlou V, Cienfuegos S, Lin S, et al. Effect of Time-Restricted Eating on Weight Loss in Adults With Type 2 Diabetes: A Randomized Clinical Trial. JAMA Netw Open. 2023;6(10):e2339337. doi:10.1001/jamanetworkopen.2023.39337