Positives

• Patients completing the 5-day ProLon cycle described losing bloating, feeling lighter, and reconnecting with hunger and satiety cues by the end of week one Healthline.
  
  

Negatives

• Patients on Mayo Clinic Connect reported scary post-fast experiences after extending ProLon with additional water-fast days, including syncope and prolonged weakness Mayo Clinic Connect.
  
  
• Patients commonly describe persistent headaches, dizziness, low motivation and trouble concentrating during the fast itself Healthline.
  
  

Hurdles & Side Effects

• A patient with a history of disordered eating, pregnancy, or breastfeeding is told the fasting-mimicking diet is contraindicated, ruling out a meaningful share of Long COVID patients The Celiac MD.
  
  
• Many patients describe the energy collapse as severe enough that they cannot keep working, walking, or caregiving during the five days STAT News.