Markers of adipose tissue inflammation are transiently elevated during intermittent fasting in women who are overweight or obese.

Objective: This study compared the effects of daily calorie restriction (DR) versus intermittent fasting (IF) on markers of inflammation and extracellular matrix deposition in adipose tissue and skeletal muscle in a controlled feeding trial in women with overweight or obesity.

Methods: Women (N = 76) were randomised to one of three diets and provided with all foods at 100% (IF100) or 70% (IF70 and DR70) of calculated energy requirements for 8 weeks. IF groups ate breakfast prior to fasting for 24-h on 3 non-consecutive days/week. Weight, body composition, serum non-esterified fatty acids (NEFA), tumour necrosis factor-alpha (TNFα), interleukin-6 (IL-6), interleukin-10 (IL-10), M1- and M2-macrophage markers by qPCR and immunohistochemistry in adipose tissue and skeletal muscle were measured following a 12-h overnight fast (fed day, all groups) and a 24-h fast (IF groups only).

Results: IF70 resulted in greater weight and fat losses and reductions in serum NEFA versus DR70 and IF100 (P < 0.05) after fed days. Markers of inflammation in serum (TNFα, IL6 and IL10), subcutaneous adipose tissue and skeletal muscle (CD68, CD40 and CD163) were unchanged by DR or IF after fed days. After fasting, NEFA, M1-macrophages (CD40) in adipose tissue, and M2-macrophages (CD163) in muscle were increased in IF70 and IF100 (all P < 0.05) and the changes in NEFA and mRNA of pan-macrophage marker CD68 in adipose tissue were positively correlated (r = 0.56, P = 0.002).

Conclusions: Unlike caloric restriction, IF transiently elevated markers of macrophage infiltration in adipose tissue and skeletal muscle, possibly in response to marked increases in adipose tissue lipolysis.