Inclusion Criteria (RADIGAL1):

• 18 years old or older
• presenting with biliary colic in the ED or outpatient clinic, with the surgical team deciding to proceed with non-operative treatment (Group 1)
• presenting with acute calculous cholecystitis in the ED, with the surgical team deciding to proceed with non-operative management (Group 2)

Exclusion Criteria (RADIGAL1):

• history of gastrointestinal disease which might affect diet, e.g., inflammatory bowel disease, irritable bowel syndrome, short bowel syndrome
• inability to provide informed consent
• unwillingness to adhere to the recommended diet
• food allergies or intolerances that would prevent following the diet
• dietary habits (e.g., vegetarians, vegans) that preclude adherence to the recommended diet
• gallstone related cholangitis without biliary colic or cholecystitis
• complications from acute pancreatitis, such as pseudocysts, walled off necrosis, among others

Inclusion Criteria (RADIGAL2):

• 18 years old or older
• undergoing uncomplicated cholecystectomy (open or laparoscopic without bile duct exploration) due to a history of biliary colic (Group 1)
• undergoing uncomplicated cholecystectomy (open or laparoscopic without bile duct exploration) due to acute cholecystitis (Group 2)

Exclusion Criteria (RADIGAL2):

• history of gastrointestinal disease which might affect diet, e.g., inflammatory bowel disease, irritable bowel syndrome, short bowel syndrome
• inability to provide informed consent
• unwillingness to adhere to the recommended diet
• food allergies or intolerances that would prevent following the diet - dietary habits (e.g., vegetarians, vegans) that preclude adherence to the recommended diet
• gallstone related cholangitis without biliary colic or cholecystitis
• complications from acute pancreatitis, such as pseudocysts, walled off necrosis, among others
• choledocholithiasis
• complicated cholecystectomy
• patients undergoing subtotal cholecystectomy
• whether primary operation differs from cholecystectomy (e.g., colectomy)
• patients having treated with percutaneous cholecystostomy