This is the companion piece to the full cholesterol article, written for the specific situation where you have already had the blood test, the LDL or ApoB has come back high, and you want to know what to do about it rather than read another round of the harmless-versus-deadly argument. The short version is that this is a manageable problem with a clear sequence of sensible steps, and that the right response is neither to panic nor to wave it away. Here is the sequence.

First, do not make a decision on a single number

A one-off high reading is not yet a problem, it is a prompt to measure properly. Cholesterol fluctuates, labs vary, and a heavy fat-rich meal in the day or two before the draw can move things. Before you change anything, get a second test done properly: a morning sample, fasted if your clinic asks for it, ideally at the same laboratory so the numbers are comparable. If two readings weeks apart agree, you have something real to work with. If they disagree wildly, the first one was noise.

While you are at it, ask for the right test. A standard panel reports LDL cholesterol, which estimates the amount of cholesterol your LDL particles are carrying. What actually drives arterial disease is the number of those particles, and that is measured directly by ApoB. On a diet that changes the size and behaviour of your particles, the two can diverge, and ApoB is the more reliable read. If your LDL is up, ask your doctor for an ApoB measurement. It is cheap, widely available, and it is the single most useful number you can have in this situation. It is also worth measuring lipoprotein(a) once in your life, an inherited particle that standard diets and tests usually ignore but that meaningfully raises risk in some people.

Second, work out your actual risk, not just your lipids

A number on its own does not tell you what to do. The same ApoB means something different in a 35-year-old with no family history and a clean metabolic profile than in a 58-year-old whose father had a heart attack at 50. Risk is cumulative: the European Atherosclerosis Society, reviewing the genetic, epidemiological and trial evidence, concluded that ApoB-carrying particles such as LDL are a cause of atherosclerosis rather than merely a marker, and crucially that the damage depends on both how high the particle count is and how long it stays high. A very high ApoB for two years is not the same exposure as a very high ApoB for twenty.

This is why, if your numbers are high and you want to know whether it is doing anything, the most informative step is to look. A coronary artery calcium score is a quick, low-radiation scan that shows whether you have actually accumulated calcified plaque. A CT angiogram shows soft plaque too. A score of zero in a younger person is genuinely reassuring and buys you time to act calmly; a raised score turns an abstract argument into a concrete reason to lower the number. Discuss with your doctor whether imaging is appropriate for your age and risk, because it converts speculation into information, and information is what lets you respond proportionately rather than emotionally.

Third, understand why yours rose, because it changes the response

There are two broad reasons LDL and ApoB climb on keto, and they are not the same problem.

The first is the ordinary one: a diet very high in saturated fat raising LDL through the familiar mechanism, in a person who may also carry extra weight or metabolic issues. Here the fix is the conventional one, and the levers below work well.

The second is the striking pattern often called the lean mass hyper-responder. These people are typically slim, fit and metabolically healthy, and when they restrict carbohydrate they show a distinctive trio: very high LDL, alongside high HDL and low triglycerides. The thresholds the researchers who named it used were an LDL at or above 5.2 mmol/L (200 mg/dL), HDL at or above 2.1 mmol/L (80 mg/dL), and triglycerides at or below 0.8 mmol/L (70 mg/dL). The survey work that characterised the phenotype found that the leaner the person, the bigger the LDL rise tended to be, which is the opposite of the usual clinical picture. The proposed explanation, the lipid energy model, is that a lean body running mostly on fat exports a great deal of fat from the liver in particles that, as they deliver their cargo, leave more LDL behind in the blood.

It is worth being clear about the status of that idea. It is a plausible hypothesis with a coherent mechanism, and it is the reason many keto enthusiasts argue their own high LDL is benign. It is not a clean bill of health. The most prominent attempt to prove the point, a study that imaged the arteries of around 100 of these hyper-responders, had its headline claim that ApoB did not predict plaque retracted in 2026, after the journal and outside researchers found the analysis had drifted from the outcome it set out to measure and that plaque had in fact progressed over the year of the study. So if you fit the hyper-responder pattern, the honest position is that your low triglycerides and high HDL are genuinely good, but they do not earn you a free pass on a very high ApoB. Knowing you fit the pattern simply tells you which lever is likely to work best, which is the next section.

Fourth, the levers that actually lower ApoB

If you and your doctor decide the number is worth bringing down, these are the tools, roughly in order of how specific they are to the keto situation.

Reintroduce some carbohydrate. This is the lever unique to the hyper-responder, and it follows directly from the mechanism: if the high LDL is being driven by the body shipping fat around in the absence of carbohydrate, then easing the degree of restriction tends to bring it down. You do not necessarily have to abandon low-carb eating, only to move from a very strict version toward a more moderate one, replacing some dietary fat with whole-food carbohydrate such as legumes, fruit or tubers. This effect is well documented at the level of individuals and self-experiments and is a reasonable first thing to try, though it has not been pinned down in large trials, so treat it as a sensible experiment you verify with a repeat test rather than a guarantee.

Change the type of fat. Independent of how much carbohydrate you eat, swapping saturated fat for unsaturated fat lowers LDL reliably. In practice that means leaning away from butter, coconut oil, fatty processed meats and cheese as your main fats, and towards olive oil, nuts, avocado, and oily fish. You can do this and remain firmly in ketosis; it is a change of fat sources, not of carbohydrate.

Add soluble fibre and consider plant sterols. Soluble fibre, from sources such as psyllium, oats within your carb budget, flax, and vegetables, modestly lowers LDL and is worth having anyway for the gut. Plant sterol supplements or fortified foods give a further small reduction. Neither is dramatic alone, but they stack with the bigger levers.

Lose visceral fat, if you have it to lose. For the overweight responder this is central, because losing abdominal fat improves the whole lipid and metabolic picture. For the already-lean hyper-responder there is little to take off, which is exactly why the carbohydrate lever matters more for them.

Medication, where the risk warrants it. If your ApoB is very high, your imaging shows plaque, or your overall risk is significant, lipid-lowering medication is an option to discuss seriously rather than dismiss. A statin, ezetimibe, or both, can bring ApoB down substantially, and the decision should be made with your doctor on the basis of your whole risk picture, not on diet ideology. Choosing to lower a high ApoB is not an admission that keto failed; it is treating a measurable risk factor with a tool that works.

Fifth, re-test and track the trend

Whatever you change, give it eight to twelve weeks and measure again, ApoB included. One number is a snapshot; the trend is what matters. If a moderate add-back of carbohydrate or a switch to unsaturated fats has dropped your ApoB into a comfortable range, you have your answer and your eating pattern. If it has barely moved and your risk is real, that points toward the medication conversation. Either way you are now responding to data about your own body rather than to anyone’s slogans, which is the entire point.

The bottom line

A high LDL or ApoB on keto is a common, solvable situation. Confirm it with a repeat test and an ApoB measurement, put it in the context of your real risk and ideally an artery scan, work out whether you are an ordinary responder or a lean hyper-responder, and then use the levers, easing carbohydrate restriction, switching the type of fat, adding fibre, losing visceral fat, or medication, in proportion to that risk. The one thing not to do is assume the number is harmless because your other markers look good and a popular argument says so. Measure, contextualise, and act. Most people who do this end up either reassured or in control, and both are far better places to be than wilfully not looking.

This is general information about the ketogenic diet, not medical advice. Cholesterol and cardiovascular risk must be assessed and managed by a doctor, who can interpret your numbers in the context of your full history. Do not start, stop or change cholesterol medication on your own. If you are pregnant, on medication, or have existing heart disease, seek professional advice before changing your diet.

Sources: Elevated LDL Cholesterol with a Carbohydrate-Restricted Diet: Evidence for a “Lean Mass Hyper-Responder” Phenotype. Current Developments in Nutrition. 2022. Read it here. Low-density lipoproteins cause atherosclerotic cardiovascular disease: a consensus statement from the European Atherosclerosis Society Consensus Panel. European Heart Journal. 2017. Read it here. Retraction notice for the KETO-CTA longitudinal paper (Plaque Begets Plaque, ApoB Does Not). JACC: Advances. 2026. Read it here.