Fasting means no food or calorie-containing drinks for a defined period before collection. Plain water is almost always allowed and is in fact encouraged, because hydration makes the draw easier.
Lipid profiles, fasting blood sugar and fasting insulin typically require 8 to 12 hours. Thyroid panels, HbA1c and most vitamin tests generally do not need fasting.
Early morning collection is usually preferred for fasting panels, simply because the fasting window falls naturally overnight.
Tell the collection technician about any regular medication. Do not stop a prescribed medicine before a test unless your doctor has specifically told you to.