Related Experiment Video
Updated: Sep 9, 2025
Assessment of the Metabolic Effects of Isocaloric 2:1 Intermittent Fasting in Mice
Published on: November 27, 2019
Three-week Alternate-day Fasting Improves Myocardial Flow Reserve and Reduces Oxygen Use in Overweight Individuals
Mette Louise Gram Kjærulff1,2,3, Thien Vinh Luong1,2,3, Ole Lajord Munk1,3
1Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
Context:
Alternate-day fasting (ADF) is a dietary regimen with prolonged fasting periods associated with metabolic and cardiovascular benefits. It remains unclear if ADF improves cardiac function and metabolism to explain these benefits.
Objective:
This study aimed to investigate the effects of a 3-week ADF intervention on myocardial efficiency, perfusion, and substrate metabolism in overweight/obese individuals.
Methods:
Sixteen participants with overweight (body mass index: 32 ± 1.9 kg/m2) completed this randomized crossover study comparing ADF with a standard diet. Dynamic cardiac positron emission tomography scans were performed using 5 tracers: [15O]water to assess myocardial blood flow and flow reserve (MFR), [11C]acetate to measure myocardial oxygen consumption (MVO2) and myocardial external efficiency (MEE), and [11C]β-hydroxybutyrate, [11C]palmitate, and [18F]fluorodeoxyglucose to assess metabolism of β-hydroxybutyrate (OHB), free fatty acid (FFA), and glucose, respectively. Blood samples were analyzed for OHB, FFA, glucose, lactate, and insulin. Blood pressure, heart rate, cardiac output, and left ventricular mass, ejection fraction, and volumes were assessed.
Results:
ADF increased circulating ketones on fasting days (peak: 0.67 ± 0.09 mmol/L), which remained elevated on eating days (0.20 ± 0.03 mmol/L). However, myocardial substrate metabolism remained unaltered following ADF. Blood pressure and cardiac output significantly decreased after ADF (systolic/diastolic: 13/9 mmHg and 0.5 L/min, respectively; P < .001). MVO2 decreased by 10% (P = .01) and total left ventricular energy use by 19% (P < .01). Resting myocardial perfusion decreased by 9% (P < .05), and MFR increased by 34% (P < .01).
Conclusion:
A 3-week ADF regimen reduced blood pressure and MVO2, and improved MFR, suggesting ADF may provide a nonpharmacological strategy to improve cardiovascular health in individuals with overweight.
Related Concept Videos
01:24Metabolic States of the Body: Fasting and Starvation
01:20Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
01:22Heart Failure VI: Adjunct Therapies
01:18Metabolic States of the Body: The Postabsorptive State
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...