Oral Presentation Australian & New Zealand Obesity Society 2016 Annual Scientific Meeting

Weight loss and tissue remodelling following 8-week calorie restriction or intermittent fasting in females who are overweight and obese (#57)

Bo Liu 1 2 , Amy T Hutchison 1 2 , Campbell H Thompson 1 , Gary A Wittert 1 2 , Leonie K Heilbronn 1 2
  1. Discipline of Medicine, the University of Adelaide, Adelaide, SA, Australia
  2. South Australian Health and Medical Research Institute, Adelaide, SA, Australia

Tissue remodelling and changes in macrophage polarisation occur in adipose tissue (AT) and skeletal muscle (SM) in response to nutrient availability in animals [1-4]. This study aimed to compare the effects of daily calorie restriction (CR) versus intermittent fasting (IF) on markers of AT and SM remodelling in women.  

Women (N=75, 50.3±1.0y, BMI 32.4±0.5 kg/m2) were randomised to 1 of 3 groups for 8 weeks, and provided with foods at 70% (IF70 and CR70), or 100% (IF100) of energy requirements. CR70 participants consumed food daily, whereas IF participants ate breakfast, prior to initiating a 24-hour fast, for 3 non-consecutive days/week. Fasting bloods, subcutaneous abdominal AT and quadriceps muscle biopsies were obtained at baseline, and 8 weeks, after a 12-h overnight fast (all groups), and 24-h fast (IF groups). Markers of macrophages and extracellular matrix (ECM) were examined by qPCR. 

We observed significant weight loss after 8 weeks, with greater weight loss in IF70 vs. CR70 and IF100 (P<0.05). Insulin sensitivity, assessed by HOMA-IR, was improved in IF70 and CR70 following a 12-h fast and in all groups following a 24-h fast, with greatest improvement in IF70 (P<0.05). Reductions in NEFAs were greater in IF70 vs. CR70 after a 12-h fast, whereas NEFAs increased after a 24-h fast in IF groups (P<0.05). In AT, CD40 expression (M1-macrophage marker) was increased following a 24-h fast in IF70 and MMP2 (involved in breakdown of ECM), was increased in CR70 and IF70 (P<0.05). In SM, CD163 (M2-macrophage) expression was increased after 12- and 24-h fasts in fasting groups (P<0.05).

Weight loss stimulated markers of ECM remodelling in AT. IF increased pro-inflammatory M1 macrophage in AT and anti-inflammatory M2 macrophages in muscle. We speculate this increase in macrophages may be an appropriate response to buffer increased lipolysis in response to severe energy deprivation.