Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Weight loss and resting energy expenditure during intermittent versus continuous energy restriction in women with obesity (the MATADOR2 Study) (129073)

Hayley M O'Neill 1 , Andrew P Hills 2 , Rachel E Wood 2 , Neil A King 3 , Ingrid J Hickman 4 , Amanda Sainsbury-Salis 5 , Nuala M Byrne 2
  1. Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, Australia
  2. School of Health Sciences, University of Tasmania, Launceston, TAS, Australia
  3. Faculty of Health, School of Exercise & Nutrition Sciences, Queensland University of Technology, Brisbane , QLD, Australia
  4. Faculty of Health, Medicine and Behavioural Sciences, University of Queensland, Brisbane, QLD, Australia
  5. School of Human Sciences, The University of Western Australia, Perth, WA, Australia

Background/Objectives: Our proof‐of‐concept study in men with obesity showed that interspersing 2‐week blocks of energy balance (EB) after every 2 weeks of energy restriction (ER) improved weight loss over continuous ER. However, we did not examine resting energy expenditure (REE) during these 2‐week EB blocks. The second Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound study (MATADOR2) study investigated: [1] if 2-week EB blocks ameliorate reductions in REE commonly seen during ER; and [2] if, as previously shown in men, intermittent ER improves weight loss over continuous ER in women with obesity.

Participants/Methods: Fifty-three women with obesity were randomised to 12 weeks of either: [1] continuous (CON), or [2] intermittent (INT) ER completed as 6×2-week blocks of ER alternating with 5×2-week blocks of energy balance (22 weeks total). Fifty-two participants completed a 4-week baseline phase (CON: N=24, 41±7y, 96.9±12.4kg, 35.4±3.8 kg.m‑2; INT: N=28, 40±7y, 98.9±11.8kg, 35.7±3.5 kg.m-2). During ER, energy intake was equivalent to 65% of weight maintenance requirements in both groups. Body weight, fat mass (FM), fat-free mass (FFM), and resting energy expenditure (REE) were measured throughout the study.

Results: For the N=18 INT and N=17 CON who completed the 12-week energy restriction intervention and 4-week post-intervention energy balance, weight loss was greater for INT (10.4±4.1 vs 8.5±1.8 kg; P=0.02). Weight change during the 5´2-week INT energy balance blocks was minimal (-0.2±0.2 kg). Despite larger weight loss in INT, absolute REE did not differ between groups after 12 weeks of energy restriction (INT: ‑568±489 vs CON: -606±428 kJ/d; P=0.2), nor after adjusting for changes in body composition (P>0.05). REE was partially restored in the INT group after each 2‐week EB block by, on average, 166 ± 259 kJ/d (P=0.01).

Conclusions: Interrupting ER with energy balance ‘rest periods’ may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency.