by Bianca Garilli, ND
Although originally (and still) used as a therapeutic approach to reduce seizures in children with intractable epilepsy, nowadays the ketogenic diet is more well-known and broadly used for weight loss and cardiometabolic disease management.
A question frequently asked when considering the implementation of a low-carbohydrate, high-fat diet is whether there are potential negative health outcomes associated with this approach, such as worsening cholesterol levels. Unfortunately, the answer to this question is not cut and dry and is dependent on many potential variables including ethnicity, length of time diet is utilized, amount of carbohydrate intake (<20 g/day; <50 g/day; <100 g/day, etc.), level of exercise/activity, and whether the type of fat in the diet is predominately unsaturated or saturated.1-7
Reviews of the literature have shown that in non-epileptic, obese individuals with metabolic dysfunction, as well as in healthy participants, the ketogenic diet has been associated with many positive changes in cardiometabolic biomarkers:1-2
- Reductions in total cholesterol and triglycerides
- Increases in HDL cholesterol
- Increase in size and volume of LDL cholesterol particles (a marker indicating a reduction in cardiovascular disease risk)
- Improvements in glucose control and reductions in insulin resistance and diabetes medication use
- Reduction in 10-year atherosclerotic cardiovascular disease risk score
- *Variable* changes (decrease or increase, depending on the study) to LDL cholesterol
Does keto impact cholesterol levels? It depends…
As with most compilations of scientific literature, variety exists between studies, depending on a variety of facets and differences in study design.1
Saturated or unsaturated fats?: The predominant type of fat incorporated into the high-fat keto regimen can differ from study to study. The majority of studies that have observed an increase in LDL cholesterol levels following a ketogenic diet report high levels of saturated fats rather than unsaturated fats,1 or diet records were not included so the fat composition is unknown.2
Ethnicity: Still another study suggests that ethnicity may play a role in whether a ketogenic diet positively or negatively affects triglyceride levels. In one particular study, white subjects experienced a larger reduction in triglyceride levels than black subjects, although neither group had a significant change in total, HDL, nor LDL cholesterol levels.4
Time on diet: The negative or positive effects on lipid levels may also be impacted by the length of time that the individual maintains the ketogenic dietary protocol. A study published in Molecular and Cellular Biochemistry employed the keto diet for 56 weeks in 66 healthy obese participants and found a beneficial impact on lipid levels.5 There was a significant decrease in body weight and BMI, as well as a significant decrease in total cholesterol, LDL cholesterol, triglycerides, and blood glucose levels, while HDL cholesterol increased significantly.5 These results were seen in individuals with both high and normal initial cholesterol levels.5 It is important to note, however, that in this particular study the carbohydrate intake level was maintained below 20 grams/day, limiting the sustainability of this regimen over the long term for most participants.5
Macronutrient profile: Although data is limited, high-protein, medium-carbohydrate diets may improve total and LDL cholesterol levels better than ketogenic approaches.1 One investigation even found no difference in total and LDL cholesterol levels after 12 months on the ketogenic diet vs. a conventional diet (except at the 3-month time point, when LDL cholesterol levels were transiently lower in the conventional diet group).3
A study published in the Annals of Internal Medicine compared a low-carbohydrate diet to a low-fat diet for the primary outcome of weight loss, while also gathering relevant data on lipid levels.6 After 2 years on each of the diets, there were no differences observed between the two groups for weight loss, body composition, or bone mineral density.6 Initially, the low-carbohydrate group experienced a greater reduction in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels; however, this group was also found to have less of a reduction in LDL and more adverse symptom reports than the low-fat group.6 HDL levels were increased the most in the low-carbohydrate group, with nearly a 23% increase at the 2-year mark.6
Another study looking at diets with varying macronutrient profile was recently published in Diabetes Care. In this study, a low-carbohydrate diet consisting of high-unsaturated/low-saturated fat diet was compared to a high-unrefined carbohydrate, low-fat diet in 93 participants for 24 weeks.7 Both groups experienced lowering of LDL levels, while the low-carbohydrate group had a greater reduction in triglycerides and increase in HDL cholesterol.7
The “skinny” on the keto diet and cholesterol levels
Simply put, the answer to the question “will a ketogenic diet raise my cholesterol levels” is actually quite complex. Overall, the science to date shows benefits for most cardiometabolic biomarkers following nutritional ketosis, but it seems that the effect of the ketogenic diet on cholesterol levels may vary depending on the types of fats incorporated in the diet, the ethnicity of the individual, the time spent utilizing this dietary approach and finally, the amount of carbohydrates in the diet. No doubt, individual genetic differences play a role too. More research in the area will likely resolve some of the ambiguity for this clinical query.
If you find that you have positive health improvements while on the ketogenic diet, that you are able to sustain the protocol, and that your health goals are being met as you partner with your healthcare practitioner, then the ketogenic diet may be worthwhile employing and maintaining. It will be important and useful for you to have clinical biomarkers, including your lipid levels, measured and followed by your primary care provider to assess the efficacy of the ketogenic regimen and to further hone and personalize your dietary pattern to maximize long-term health.
- Kosinski C et al. Effects of ketogenic diets on cardiovascular risk factors: evidence from animal and human studies. Nutrients. 2017;9(5):517.
- Bhanpuri NH et al. Cardiovascular disease risk factor responses to a type 2 diabetes care model including nutritional ketosis induced by sustained carbohydrate restriction at 1 year: an open label, non-randomized, controlled study. Cardiovasc Diabetol. 2018;17(1):56.
- Foster GD et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 2003;348:2082–2090.
- Samaha FF et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med. 2003; 348:2074–2081.
- Dashti HM et al. Long term effects of ketogenic diet in obese subjects with high cholesterol level. Mol Cell Biochem. 2006;286(1-2):1-9.
- Foster GD et al. Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet; a randomized trial. Ann Intern Med. 2010;153(3):147–157.
- Tay J et al. A very low-carbohydrate, low-saturated fat diet for type 2 diabetes management: a randomized trial. Diab Care. 2014;37(11):2909-18.
Bianca Garilli, ND, USMC Veteran
Dr. Garilli is a former US Marine turned Naturopathic Doctor (ND). She works in private practice in Northern California and runs a consulting company partnering with leaders in the natural and functional medicine world such as the Institute for Functional Medicine and Metagenics. She is passionate about optimizing health and wellness in individuals, families, companies and communities- one lifestyle change at a time. Dr. Garilli has been on staff at the University of California Irvine, Susan Samueli Center for Integrative Medicine and is faculty at Hawthorn University. She is the creator of the Veterans for Health Initiative and is the current President of the Children’s Heart Foundation, CA Chapter.