Three-week Alternate-day Fasting Improves Myocardial Flow Reserve and Reduces Oxygen Use in Overweight Individuals
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".