How fast can ApoB come down?
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Fast, once the food really changes. In a 2019 feeding trial, each diet ran four weeks, and by the end of each one ApoB had moved with the food. Medicine moves it further. Across 11 trials of LDL-lowering medicine, ApoB fell 33% on average. Retest 6 to 12 weeks after your change, at the same lab.
What we’d do
Make the change, keep it for at least six weeks, then retest. Halve the saturated fat and move your protein toward beans, lentils and tofu, since those are the two food changes with ApoB sizes from trials. Then judge the result against the noise between two tests, which at 100 is about 15 points, and expect a few retests before a food change stands out from the noise.
Why it moves in weeks
Your liver keeps making these particles and clearing them out of your blood, all the time. Change what goes in and the count follows. In the feeding trial, 113 adults ate three diets for four weeks each, in random order, with all their food provided except fresh produce. Their weight was held steady, so weight loss didn’t explain the changes.
Four weeks on each diet, 10 points apart.
The two ends of the 2019 feeding trial: high saturated fat with red meat, and low saturated fat with plant protein. These were two different groups of people, so the gap isn’t one person’s drop.
It’s like a bathtub with the tap on and the drain open. Turn the tap down or open the drain wider and the water level changes within weeks.
How long each thing takes
| What | How fast | Source |
|---|---|---|
| Halving saturated fat | About 6 to 7 points within 4 weeks | 2019 feeding trial, 113 adults |
| Beans, nuts and soy in place of meat | About 3 to 4 points within 4 weeks | Same trial |
| Psyllium or oats | About 5 and 3 points, in trials of 3 weeks or more | Two reviews, 28 and 58 trials |
| LDL-lowering medicine | About 33% on average | 11 trials, pooled by the National Lipid Association |
The 2026 US guideline checks lipids 4 to 12 weeks after a medicine is started or changed, and every 6 to 12 months after that.
Why a quick retest can fool you
Two ApoB tests can differ by about 15% by chance, because your body moves about 6% between tests and the lab adds 5 to 6%. A real 6 point drop from halving saturated fat can hide inside that, or look twice as big. A retest at two weeks can’t tell a real change from luck, and even at eight weeks one test can mislead. Two draws a few days apart at each end narrow the band to about 11%.
What can slow it down
Fast weight loss is on the guideline’s list of causes of high LDL, so retest once your weight has held for a few weeks. In women, ApoB jumps in the year either side of the last period, which can hide a drop. And a food change that slips after a month will likely show up as a rise, since the count follows what you’re eating now. Did my ApoB really change? checks two results against the noise.
5 sources
- 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
- Soffer DE, Marston NA, Maki KC and others, Role of apolipoprotein B in the clinical management of cardiovascular risk in adults: an Expert Clinical Consensus from the National Lipid Association, Journal of Clinical Lipidology, 2024pmc.ncbi.nlm.nih.gov
- 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
- Kafonek SD, Derby CA and Bachorik PS, Biological variability of lipoproteins and apolipoproteins in patients referred to a lipid clinic, Clinical Chemistry, 1992pubmed.ncbi.nlm.nih.gov
