Fasting, coffee, supplements and exercise: a short checklist so your results reflect the everyday you.
Aug 12, 2026
4 min read
Dr. Rohan Desai
How you prepare changes results more than most people expect. None of it is complicated, but getting it wrong is the most common reason we have to repeat a panel.
The night before
If your panel covers lipids or fasting insulin, stop eating ten hours before the draw. Water is fine, even encouraged: dehydration concentrates your blood and skews several markers. Avoid alcohol for 24 hours, since it moves triglycerides and liver enzymes sharply.
The morning of
Black coffee isn’t neutral: it lifts cortisol and can nudge glucose, so save it for afterward. Stop biotin for 48 hours, because it interferes with thyroid and hormone assays. Skip a hard workout that morning; it raises CK and can make a healthy liver panel look worrying.
Everything else stays the same. Take prescribed medication as usual unless we’ve said otherwise, and tell us what you take so we can read the numbers in the right context.
Dr. Rohan Desai
Internal medicine, Tinsdale
