Short answer
Usually not for the result itself. The 2016 European consensus on lipid testing says ApoB and Lp(a) are not affected by whether you have eaten. A normal meal mainly raises triglycerides. Your lab or doctor may still ask you to fast if ApoB is drawn with other tests, so follow the instructions you are given.
What the evidence says
In 2016 the European Atherosclerosis Society and the European Federation of Clinical Chemistry published a joint consensus on non-fasting lipid tests in the European Heart Journal. Drawing on large studies, including 92,285 people in Copenhagen and 209,180 in Calgary, it states that HDL cholesterol, ApoA1, ApoB and Lp(a) are not affected by fasting or non-fasting status.
What a meal does change
The same consensus measured the biggest average changes one to six hours after normal meals. Triglycerides rose by about 26 mg/dL. Total cholesterol, LDL cholesterol and non-HDL cholesterol each fell by about 8 mg/dL, and HDL did not change. Those shifts are small for most people. The 2018 AHA/ACC cholesterol guideline in the US also says screening can be done fasting or non-fasting.
Why you may still be asked to fast
ApoB is often ordered alongside a lipid panel, glucose or other tests, and some of those, or some labs, still call for fasting. Fasting is also commonly requested when triglycerides were very high before. So the simple rule: the ApoB number itself doesn't need it, but follow your lab's or doctor's prep instructions for the whole order. If you are unsure, call the lab before you go. Educational content, not medical advice.
Related questions
Can I drink water before an ApoB test?
Water is normally allowed even when fasting is required. Follow the instructions on your lab order.
Does Lp(a) need fasting?
The 2022 European consensus on Lp(a) says fasting has no effect on Lp(a) levels.
Read next
Sources
Published 2026-10-04 · Last checked 2026-10-04
Educational content, not medical advice. Made for the United States.