Alternate-day fasting lessens oxygen use, enhances MFR in overweight individuals

An alternate-day fasting (ADF) regimen for 3 weeks results in lower blood pressure and myocardial oxygen consumption (MVO₂) and improves myocardial blood flow and flow reserve (MFR), reports a recent study.

This randomized crossover study compared ADF with a standard diet in 16 participants with overweight (BMI 32 kg/m²).

The investigators conducted dynamic cardiac positron emission tomography scans using five tracers: [¹⁵O]water to assess MFR; [¹¹C]acetate to measure 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.

The investigators analysed blood samples for OHB, FFA, glucose, lactate, and insulin. They also assessed blood pressure, heart rate, cardiac output, and left ventricular mass, ejection fraction, and volumes.

Participants on ADF exhibited increased circulating ketones on fasting days (peak, 0.67 mmol/L), which persisted on eating days (0.20 mmol/L), but their myocardial substrate metabolism did not change.

The ADF regimen significantly reduced blood pressure and cardiac output (systolic/diastolic: 13/9 mm Hg and 0.5 L/min, respectively; p<0.001) and led to a decrease of 10 percent in MVO₂ (p=0.01) and 19 percent in total left ventricular energy use (p<0.01). ADF also reduced resting myocardial perfusion by 9 percent (p<0.05) and increased MFR by 34 percent (p<0.01).

These findings suggest that “ADF may provide a nonpharmacological strategy to improve cardiovascular health in individuals with overweight,” the investigators said.

“ADF is a dietary regimen with prolonged fasting periods associated with metabolic and cardiovascular benefits,” they said.