A ketogenic diet typically leads to a broad range of improvements in blood lipids as well as other cardiovascular risk factors such as blood pressure and inflammation. However, the changes we see in total and LDL cholesterol levels are much less predictable than the changes in other blood lipids such as triglycerides and HDL cholesterol. For some people, calculated LDL cholesterol goes down, and for others it goes up, sometimes quite a bit. This tendency for some people to see an increase in their LDL cholesterol has been a focus of research over the last decade because the question remains - “What, if anything, does this tell us when assessing one’s risk of heart disease?”
One approach to this question has been to examine the variations in the size of the LDL particles in the blood. With a well-formulated ketogenic diet, we see a shift away from the small dangerous LDL even when the total LDL goes up, so most of this increase is in the ‘good’ or ‘buoyant’ LDL fraction (Hallberg, 2018). Another factor to be taken into account is that during rapid weight loss, cholesterol that you had stored in your adipose tissue (ie, body fat) is mobilized as the fat cells shrink (Phinney 1990). This will artificially raise serum LDL as long as the weight loss continues, but it then comes back down once weight loss stops. To avoid being misled by this, the best strategy is to hold off checking blood lipids until a couple of months after weight loss ceases.
And finally, there is increasing debate over the importance of the standard (i.e., calculated) LDL cholesterol level relative to the sum of other cardiovascular risk factors. This controversy makes it difficult for the individual patient to weigh the evidence from the various known risk factors. If you are uncertain, it is a good idea to follow up with your physician, who may recommend performing the most up-to-date assessment of your blood lipids, including the size and amounts of your LDL cholesterol fractions with a NMR or VAP lipoprotein test.
You can read more about blood lipid changes with a ketogenic diet for an in-depth look at the controversial use of the LDL cholesterol to assess heart disease risk.
Hallberg SJ, McKenzie AL, Williams PT, et al. Effectiveness and safety of a novel care model for the management of type 2 diabetes at 1 year: an open-label, non-randomized, controlled study [published online ahead of print February 07, 2018]. Diabetes Ther. doi: 10.1007/s13300-018-0373-9.Phinney SD, Tang AB, Waggoner CR, Tezanos-Pinto RG, Davis PA. The transient hypercholesterolemia of major weight loss. The American Journal of Clinical Nutrition, Volume 53, Issue 6, 1 June 1991, Pages 1404–1410. https://doi.org/10.1093/ajcn/53.6.1404