Eur J Clin Nutr. 2026 Apr 17. doi: 10.1038/s41430-026-01749-8. Online ahead of print.
ABSTRACT
INTRODUCTION: Water fasting involves completely abstaining from all caloric intake. Multiple studies have demonstrated that water fasting for up to 21 days is well-tolerated, but none focused on patients with severe obesity (body mass index ≥ 40) or utilized treatment with glucagon-like peptide-1 receptor agonists (GLP-1).
METHODS: The patient was a 44-year-old male with severe morbid obesity, heart failure, oxygen-dependent obesity hypoventilation syndrome, uncontrolled hypertension, anemia, and depression. He underwent a 27 day inpatient fast with weekly tirzepatide, including 21 day water fast with structured refeeding.
RESULTS: The patient lost 125 pounds during the fast. He regained independent ambulation and chronic oxygen supplementation was discontinued. Chronic anemia resolved and depression improved as measured by Patient Health Questionnaire. Systolic blood pressure improved despite discontinuation of his antihypertensives. His chronic leg wound resolved without antibiotics. Left ventricular mass decreased and fasting insulin normalized. Appetite remained tolerable, and the only complication was mild transaminitis.
CONCLUSION: This case suggests prolonged medically-supervised water fasting with GLP-1 use is an effective short-term weight reduction strategy that allows for bridging to bariatric surgery with improvement in multiple chronic diseases. As the fast ended for surgery rather than intolerance, research into longer water fasts could be considered.
PMID:41998348 | DOI:10.1038/s41430-026-01749-8