Background: Intermittent fasting (IF) has emerged as an alternative dietary approach for weight management, but its impact on psychological and behavioural aspects is understudied. We examined a novel IF approach (iTRE) as compared to calorie restriction (CR) and a non-intervention group (SC) on eating behaviours, mood, sleep, and quality of life (QOL).
Methods: This is an exploratory outcomes analysis of a single site, parallel design, randomized controlled trial with 6-month intervention and 12-month follow-up. Adults (n=209, 57% female; 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): (i) IF plus early time-restricted eating (iTRE, 30% of energy requirements between 8am-12pm followed by a 20-hour fasting period on three non-consecutive days weekly, ad libitum on other days), (ii) CR (70% of energy requirements daily, without time prescription), (iii) SC (health booklet). Only iTRE and CR received 6-months of nutritional support. Outcome measures including eating behaviours, mood, sleep, and QOL were assessed using questionnaires.
Results: Greater weight loss was found in iTRE (-7.4±3.1 kg) and CR (-7.0±3.1 kg) than SC (-2.4±3.1 kg) at month 6, but not month 18. Dietary restraint, disinhibition and hunger were improved in all groups, with greater dietary restraint and reduced disinhibition and hunger in CR versus iTRE at month 6. Greater dietary restraint in CR versus iTRE was sustained at month 18. There were no between-group differences in mood, sleep, or QOL at month 6 or 18, nor was there a difference in these outcomes when they were assessed after a restricted versus ad libitum eating day within the iTRE group.
Conclusion: CR had greater improvement in eating behaviours than iTRE, but there were no between-group differences in body weight, mood, sleep, and QOL, suggesting iTRE is an acceptable alternative approach to CR for these outcomes.