Effects of Intermittent Fasting or Calorie Restriction on Markers of Lipid Metabolism in Human Skeletal Muscle
Liu B, Hutchison AT, Thompson CH, Lange K, Wittert GA, Heilbronn LK
Mar 8, 2021
Journal of Clinical Endocrinology & Metabolism. 2021 Mar 8;106(3):e1389-e1399. doi: 10.1210/clinem/dgaa707.
Context: Impaired lipid metabolism is linked with obesity-associated insulin resistance, which may be reversed by caloric restriction (CR).
Objective: In a secondary analysis of a randomized controlled trial, we compared the effects of intermittent fasting (IF) and CR on markers of lipid metabolism in muscle.
Design: Seventy-six women (body mass index, 25-40 kg/m2) were randomly assigned to 1 of 3 diets for 8 weeks and provided foods at 70% (CR70 and IF70) or 100% (IF100) of energy requirements. IF groups ate breakfast prior to a 24-hour fast on 3 nonconsecutive days per week. On nonfasting days, IF70 ate at 100% and IF100 ate at 145% of energy requirements to achieve the prescribed target. Weight, body composition, insulin sensitivity by clamp, nonesterified fatty acids (NEFAs), β-hydroxybutyrate (BHB), and markers of lipid metabolism and oxidative stress in muscle by quantitative polymerase chain reaction were measured at baseline and week 8 following a 12-hour overnight fast (all groups) and 24-hour fast (IF groups).
Results: IF70 resulted in greater weight and fat loss and reduced NEFAs vs CR70 and IF100 after an overnight fast. IF70 and IF100 induced a greater reduction only in mRNA levels of antioxidant enzymes glutathione peroxidase 1 (GPX1), superoxide dismutase 1, soluble (SOD1), and SOD2 vs CR70. Fasting for 24 hours increased NEFAs and BHB in IF groups, but impaired insulin sensitivity and increased PLIN5 mRNA levels.
Conclusions: In comparison to CR, IF did not increase markers of lipid metabolism in muscle, but reduced expression of antioxidant enzymes. However, fasting-induced insulin resistance was detected, alongside increased PLIN5 expression, potentially reflecting transient lipid storage.
Keywords: calorie restriction; intermittent fasting; lipid metabolism; mitochondria; muscle; obesity.
Calorie Restriction, Intermittent Fasting, Lipid Metabolism, Mitochondria, Muscle Mass, Obesity
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