Background: Intermittent fasting (IF) and calorie restriction (CR) may have anti-inflammatory effects, although whether one is superior in reducing the inflammatory burden in adults at risk of type 2 diabetes remains unclear.
Objective: This exploratory sub-study of an open-label, parallel group, three-arm randomized controlled trial compared IF plus early time-restricted eating (iTRE) versus CR and standard care (SC) on systemic and adipose tissue markers of inflammation.
Methods: Adults (N = 209, 58 ± 10 years, 34.8 ± 4.7 kg/m2) at increased risk of developing type 2 diabetes were randomised to one of three groups (2:2:1): iTRE (30% energy requirements between 0800 and 1200 hours and followed by a 20-h fasting period on three non-consecutive days per week, and ad libitum eating on other days); CR (70% of energy requirements daily, without time prescription); or SC (weight loss booklet) for 6 months. Body weight and plasma C-reactive protein [CRP], tumour necrosis factor α [TNF-α], interleukin-6 [IL-6] and interferon-ɣ [IFNɣ]) were measured at baseline and month 6 in a subset of participants with weight loss above median (CR: N=32, iTRE: N=35) or below median (SC: N=18). The mRNA content of adipose tissue macrophage-associated genes (CD68, CD163 and ITGAX) was also assessed.
Results: In the selected subset, weight loss was greater in iTRE and CR versus SC (10.6±0.85% and 10.3±0.70% vs 0.13±0.51%, p<0.001). There were no group-by-visit or group effects detected in any systemic marker. A visit effect was observed in CRP and TNF-α levels, which were reduced at month 6 (CRP: -1.36±0.47mg/dL, p<0.001; TNF-α: -0.082±0.03pg/mL, p=0.025). In adipose tissue, there was no significant effect observed in any gene.
Conclusions: While anti-inflammatory effects were observed, there was no clear advantage to either iTRE or CR in reducing inflammatory markers in adults at risk of type 2 diabetes.