Why is my ApoB so high on keto?
Because most keto diets swap carbs for fat, and a lot of that fat is saturated. The 2026 US guideline says LDL “can be increased substantially in some individuals, particularly when there is high consumption of animal products”, and it lists ketosis among the causes of high LDL. ApoB, which counts those LDL particles, rises with it, and keto’s low triglycerides don’t cancel that out.
What we’d do
If you want to stay low carb, keep the carbs low and change the fat. Cook with olive oil, eat nuts, avocado and fish, and cut back on butter, cheese, cream and fatty meat. Retest after about a month at the same lab. If your ApoB is 140 or more, see a doctor before you plan anything. If it doesn’t come down, talk with your doctor about whether the diet still makes sense for you.
What keto does to the numbers
| Number | What tends to happen | Source |
|---|---|---|
| Weight | Down in the short term | 2026 guideline |
| Triglycerides | Down in the short term | 2026 guideline |
| LDL | Up a lot in some people, mostly with lots of animal foods | 2026 guideline |
| ApoB | Up with saturated fat, since every LDL particle carries one | 2019 feeding trial, 2026 guideline |
The guideline describes keto as cutting carbs to about 20 to 50 g a day. Since “most carbohydrates in these diets are replaced by fat, often saturated fat”, it says, some people “may manifest a severe hypercholesterolemia phenotype”, numbers that look like severe inherited high cholesterol. It asks doctors to take a careful diet history from anyone with severe high cholesterol, to rule out a high saturated fat diet as the cause.
In a 2019 feeding trial, going from about 7% to about 14% of calories as saturated fat raised ApoB about 6 to 7 points in four weeks.
- Under 60 very high risk
- Under 70 high risk
- Under 90 borderline or intermediate risk
- 120 raises risk
- 140 severe
mg/dL over g/L. Rungs from the National Lipid Association (2024), matched to the 2026 US guideline's LDL goals. Ticks from the 2026 guideline.
“But my triglycerides are great”
This is the strongest argument keto eaters make. They point to low triglycerides, high HDL and big, fluffy LDL particles, and argue that a high LDL and ApoB must be harmless with those.
The best evidence says risk follows the count. In a study of 654,783 people, gene variants that lowered triglycerides and variants that lowered LDL cut heart disease by the same amount, about 23% for every 10 points of ApoB. In UK Biobank and two drug trials, risk of heart attack “was best captured by the number” of ApoB particles, whatever they carried and whatever kind they were. Neither study tested keto directly, and we found no long trial of keto that counted heart attacks. But both point the same way, so a high ApoB on keto counts the same as a high ApoB on any other diet.
It’s like counting cars on a highway, where every car can crash, full or nearly empty.
When to see a doctor
At an ApoB of 140 or more, or an LDL of 190 or more, the guideline calls it severe high cholesterol. See a doctor, tell them about the diet, and expect them to look for other causes too. cholesterol.guide covers what keto does to LDL, and bodyfat.guide covers the insulin story keto is built on.
5 sources
- Blumenthal RS, Morris PB, Gaudino M and others, 2026 ACC/AHA guideline on the management of dyslipidemia, JACC, 2026doi.org
- The same guideline, full text, Circulation, 2026api.iscpcardio.org
- Ference BA and others, Association of triglyceride-lowering LPL variants and LDL-C-lowering LDLR variants with risk of coronary heart disease, JAMA, 2019pubmed.ncbi.nlm.nih.gov
- Marston NA and others, Association of apolipoprotein B-containing lipoproteins and risk of myocardial infarction in individuals with and without atherosclerosis, JAMA Cardiology, 2022pubmed.ncbi.nlm.nih.gov
- Bergeron N and others, red meat, white meat and plant protein on high and low saturated fat diets, a feeding trial in 113 adults, American Journal of Clinical Nutrition, 2019pmc.ncbi.nlm.nih.gov
