LDL Cholesterol: Normal Values and What a High LDL Means

Your report calls it LDL cholesterol, but in a routine lipid panel that number is almost never measured. It is worked out. The Friedewald equation takes your total cholesterol, subtracts your HDL and then subtracts your triglycerides divided by 2.2. Your LDL is therefore a derivative of three other values, and it inherits every bit of noise and every error in them.

For anyone tracking their blood seriously that is not a detail but the key to reading the result. The equation goes wrong when triglycerides are high: above roughly 4.5 mmol/l it is invalid and most laboratories will no longer report a calculated LDL. With a low LDL combined with raised triglycerides it underestimates the true value. And a meal within a few hours of the draw pushes triglycerides up, which feeds straight into the final number.

That carries an immediately useful conclusion for athletes eating low-carbohydrate. People who eat that way typically have low triglycerides. The known failure mode of the equation requires the opposite. So a high LDL alongside low triglycerides cannot be explained away as an arithmetic artefact: the number is most likely real.

More reliable routes exist. The Martin-Hopkins method replaces the fixed divisor with a person-specific factor, the Sampson-NIH equation holds to roughly 9 mmol/l of triglycerides, and a direct LDL assay measures the cholesterol in LDL particles itself, although direct assays are less well standardised between manufacturers.

There is also a point of principle. LDL measures cargo, not particle number. Atherosclerosis is driven by the number of particles entering the artery wall. You read that number better from non-HDL cholesterol and from apolipoprotein B, neither of which needs a division and neither of which can therefore go off the rails.

The question that belongs on this page is not whether LDL is bad, but what you do with an LDL that rises while you appear to be doing everything right.

First the mechanism, because fitness does not change it. Every LDL particle carries one apolipoprotein B and can enter the artery wall. The more of those particles pass through over the years, the more plaque accumulates. A low resting heart rate, a high VO2max and a low body-fat percentage do not alter that biology. Training protects your heart in many ways, but it does not make a raised particle burden harmless.

Then the phenomenon itself. A strongly high-fat, low-carbohydrate way of eating raises LDL and apolipoprotein B in a substantial minority, and the rise is typically largest in lean, insulin-sensitive, well-trained people. A recognisable pattern has even been described: a markedly raised LDL, a high HDL and low triglycerides in someone with a low body-fat percentage. That is exactly the profile many performing athletes see on a ketogenic or carnivore diet. What does it mean? The honest answer is that this is not settled. The imaging studies in this specific group are small and short. They do not prove the pattern is safe, and they do not prove it is as harmful as the same LDL from another cause. What is certain is that the number is real, and that the conversation about it belongs with a doctor who knows your full risk profile, not with a forum.

And then the line on the paper. The 3.0 mmol/l on your report is a population reference interval, not a goal. Guidelines tie the goal to risk: below 1.8 mmol/l with established cardiovascular disease up to age seventy, below 2.6 at high or very high risk, and in the European guideline down to below 1.4 at very high risk. An LDL of 2.8 is therefore normal on paper and at the same time clearly too high for anyone who has already had a heart attack. For the secondary goals, which are often more reliable than LDL itself, the numbers are these.

Finally, a category that goes unmentioned far too often in this audience: anabolic androgenic steroid use raises LDL and can sharply lower HDL, most clearly with oral forms. Anyone using them, or who has used them, should say so when a lipid panel is assessed, because otherwise the diet gets the blame while the explanation lies elsewhere.

Draw in an ordinary week, not an exceptional one. Right after an exhausting endurance session or a race your triglycerides and your HDL shift temporarily, and because your LDL is calculated from those values, your LDL shifts with them. A panel taken the morning after a marathon mostly measures your marathon. Schedule the draw in a regular training week instead, and keep the timing consistent on a repeat so you are comparing like with like.

On fasting: total cholesterol, HDL, non-HDL and apolipoprotein B do not require it. Your triglycerides are meal-sensitive, and so, by extension, is the calculated LDL. If you want to follow your LDL over time, draw fasted and stick to it.

If you have changed your diet substantially, for example to a low-carbohydrate or ketogenic pattern, give your body at least six to twelve weeks before drawing conclusions from a new result. Test straight after the switch and you measure the transition, not your new baseline.

There are also moments not to test. After surgery, an injury with prolonged inactivity or a significant infection, LDL falls for weeks, so a panel gives you a rosier picture than is warranted. Wait a few weeks after recovery.

If your LDL is unexpectedly high, have an underlying cause ruled out before you start rebuilding your diet. An underactive thyroid is the classic, easily missed explanation and is excluded with a TSH test. Poorly controlled diabetes, kidney disease, cholestasis and various medicines can raise the value too.