The phrase "advised to fast" is correct and usable in written English.
It can be used in contexts where someone is recommended or instructed to abstain from food for a certain period, often for health or religious reasons.
Example: "The doctor advised me to fast for 12 hours before the blood test."
Alternatives: "recommended to fast" or "instructed to fast".
For example, participants reported that patients are advised to fast in preparation for fasting glucose measures, and to arrive at the clinic early for the tests.
All patients were advised to fast for at least 6 h before the integrated PET/CT examination.
Patients were advised to fast for at least 6 hours prior to the scan.
Participants were advised to fast prior to specimen collection but fasting was not required.
All participants were advised to fast from 10 00 p.m. the night before and to avoid caffeine for 24 h before the study.
All participants will be advised to fast from 22 00 h and to avoid caffeine for 24 h before the study.
The patient will be advised to arrive fasting when reporting for the baseline assessment.
After the interview participants were advised to be fasting from late evening (after dinner) and until the following morning for the collection of blood samples.
Patients were urged to monitor their serum creatinine regularly and report the results to us; they were strictly advised to stop fasting if the serum creatinine rose by >10% during follow-up.
Subjects were advised to come fasting (no food or drink from 10 pm the previous evening) if they wanted their blood sugar assessed as part of a diabetes risk assessment.
In general, patients are advised to break the fast if their blood glucose is less than 70 mg/dL (3.9 mmol/L) in the early fasting hours because hypoglycemia can only worsen, especially in patients taking insulin and/or sulfonylureas.
