OBJECTIVES: Intermittent fasting (IF) has gained attention for weight management and metabolic health, but detailed trials comparing its efficacy to calorie restriction (CR) in type 2 diabetes mellitus (T2D) are limited. Our aim was to compare the impact of CR diet with or without 12-hour overnight IF regimen on weight loss, glycemic control, and reduction of medication use in T2D.
METHODS: This was a 3-month, single-center randomized clinical trial. Participants (N = 99), 21-60 years with T2D, were randomly assigned to Group 1 (12-hour IF + CR, N = 48) or Group 2 (CR alone, N = 51). Anthropometric evaluations included weight, height, waist and hip circumference, and BMI. Body composition analysis was performed, and biochemical analysis included HbA1c, FBG, and fasting insulin levels to calculate the HOMA-IR. Physical activity was assessed using the Global Physical Activity Questionnaire.
RESULTS: Both groups experienced significant weight loss after 12 weeks. The IF + CR group showed a more pronounced weight reduction (-6.51%) compared to the CR group (-4.41%) (P < 0.001) and significant improvements in HbA1c levels, with a reduction to 6.51% compared to 6.86% in the CR group (P = 0.035). The absolute reduction in HbA1c showed a significantly greater median decrease in the IF + CR group [-0.50 (IQR - 0.60 to -0.35)] compared with the CR group [-0.20 (IQR - 0.40 to -0.10)] (P = 0.002). IF + CR demonstrated significant reductions in waist circumference (-4.64%) and hip circumference (-3.12%) compared to the CR (-2.70% and -0.86%, respectively) (P < 0.05). Furthermore, IF + CR showed greater reductions in body fat mass (-9.39%) compared to the CR (-5.32%) (P < 0.001). Physical activity levels were comparable, with average MET of 100 and sedentary hours of 15.7 ( ± 3) for IF + CR and 16.2 ( ± 2.3) for CR, (P = 0.134).
CONCLUSIONS: A 12-hour intermittent fasting (IF) regimen combined with calorie restriction (CR) demonstrated superior efficacy in promoting weight loss and improving glycemic control in patients with type 2 diabetes (T2D) compared to CR alone. Integrating IF into clinical nutrition guidelines could offer a practical and effective approach to diabetes management.
CLINICAL TRIAL REGISTRATION: The study was registered at the Pan African Clinical Trial Registry (PACTR202411524439559).
