LDL/HDL Ratio: The Number That Moves the Wrong Way During Weight Loss

Work it out yourself and it is a single division: your LDL cholesterol in mmol/l divided by your HDL cholesterol in mmol/l. LDL 3.2 divided by HDL 1.3 gives 2.5. There is nothing else to it. Calculating a cholesterol ratio costs no extra tube of blood and produces no measurement that did not already exist; the lab simply does the division for you in advance.

The trouble sits above the line. In almost every Dutch laboratory your LDL is not measured but estimated, using the Friedewald formula: LDL = total cholesterol - HDL - (triglycerides / 2.2). Your LDL is therefore itself a calculated result, and this ratio is a sum performed on a sum.

That is exactly why the number behaves differently for you than for the average reader. The formula subtracts a fixed share of your triglycerides from the total. When those triglycerides drop, and during weight loss that often happens within weeks, less gets subtracted and the calculated LDL comes out higher. Not one extra LDL particle has appeared. The deduction has simply shrunk.

The denominator has behaviour of its own. In many people HDL dips slightly during the first months of an energy deficit, then creeps back up. A smaller denominator makes the fraction bigger. Numerator up, denominator down: your ratio rises from both sides at once, and neither reason has anything to do with your arteries.

And what this number never sees at all are the VLDL and remnant particles that are especially numerous in an insulin-resistant profile. They sit neither above nor below the line. Finally, do not mix the LDL/HDL ratio up with the cholesterol ratio: that one puts total cholesterol above the line and therefore sits on a different scale, with a limit around 5 rather than around 3.

For someone measuring themselves month after month, this is the worst conceivable number to steer by. Not because it is nonsense, but because in your particular situation it moves the wrong way.

Put the two movements side by side. You lose weight, your triglycerides fall sharply, and during weight loss that is one of the first and largest changes in the entire lipid profile. The estimate of your LDL subtracts a fixed share of those triglycerides, so the calculated LDL climbs. Your HDL, which often dips during the first months of an energy deficit, makes the denominator smaller. The result: a ratio that looks worse at three months than it did at the start, while your weight, your waist and your blood pressure all moved the right way. Anyone following this one figure alone concludes that things are going wrong at precisely the moment they are going right.

A second weakness sits on top of that, and it affects everyone: a proportion erases the absolute numbers. LDL 3.0 with HDL 1.0 gives 3.0. LDL 4.5 with HDL 1.5 also gives 3.0. The same figure, and yet the second case carries half again as much atherogenic cholesterol in the bloodstream. It is that absolute amount which accumulates in the artery wall over decades, not the fraction above it.

And something more fundamental is going on: no guideline steers by this. The European ESC/EAS guideline and the Dutch CVRM standard place their targets on LDL, with non-HDL cholesterol and ApoB as second choice. The LDL/HDL ratio does not appear in either. No doctor treats to it, so there is no reason for you to build a programme around it.

The alternative is simpler than the ratio itself. Non-HDL is your total cholesterol minus your HDL. Two directly measured values, no formula, no assumption about triglycerides and no requirement to fast. That is exactly why it does not break at the moment your triglycerides start moving, and that moment is the whole point of measuring through a programme. Compare it against your own baseline rather than a population limit: your direction tells you more than your place in a reference interval.

You do not order this ratio separately; it falls out of every lipid panel automatically. The real question is when you test and what you compare against.

Test fasted, and keep doing so for the whole programme. For total cholesterol and HDL a meal barely matters, but your ratio hangs on the triglycerides through the formula, and those shoot up after eating. A single non-fasting draw between two fasted ones makes your entire series incomparable. Above roughly 4.5 mmol/l of triglycerides the Friedewald formula stops being valid altogether and the number says nothing at all.

Measure a baseline before you start, then again at around three and around six months. Testing more often mostly produces noise: triglycerides fluctuate day to day by some twenty to twenty-five percent, LDL and total cholesterol by five to ten percent. A difference has to clear that band to mean anything. Include HbA1c in the same draw, because that number moves slowly enough to follow a programme lasting months honestly.

Wait a few weeks after an infection, surgery or a hospital admission: cholesterol falls temporarily in that period. And if your profile is newly abnormal, have an underlying cause ruled out first. An underactive thyroid raises LDL and is often missed, so a TSH belongs in the workup, alongside attention to poorly controlled diabetes, kidney and liver disease, heavy alcohol use and a number of medicines.

The table below shows what happens to each component through a monitored programme. It gives the direction of the effect, not a cut-off per phase.

Always have your results assessed by a doctor, together with your individual values and your full risk profile.