**Introduction / Hypothesis**
The ketogenic diet has been popularized as a rapid weight loss diet. Though advertised as safe, the cardiovascular implications of this diet have not been fully understood. Most people on the ketogenic diet develop at most a mild increase in their cholesterol levels. However, a subgroup referred to as “hyper responders” have been found to develop dramatic elevations while on the ketogenic diet. Our study identified a group of 17 patients who were found to have profound hyperlipidemia while on the ketogenic diet.

**Methods**
Between 2018 and 2022 we reviewed charts of patients who were seen in our Cardiology clinic for clinically significant elevated cholesterol content (LDL >190 mg/dL). Seventeen of these patients identified were following the ketogenic diet at the time of their evaluation. Lipid panel blood results in these patients were reviewed retrospectively prior to their initial presentation and after discontinuing the ketogenic diet.

**Results**
The average age of our patient cohort was 46 years. The average baseline LDL in patients was 129 mg/dL. After strict adherence to the ketogenic diet for a mean timeframe of 12.3 months, the mean LDL level increased by 245%. Patients who discontinued the ketogenic diet and had follow up lipid panels after an average of 9 months had a decrease in their LDL levels by an average of 220%. Five of the patients underwent genetic testing. Two of the patients were found to have a mutation of the LDL-R gene.

**Conclusion**
Our review showed that “hyper metabolizing” patients adhering to the ketogenic diet had a substantial increase in their LDL cholesterol levels on average from baseline with significant improvement in these levels after discontinuing the diet. The etiology of these changes is likely multifactorial, including a diet higher in saturated fatty acids, along with possible underlying genetic mutations as seen in 2 of our patients. Interestingly, we saw the largest percent increase in LDL cholesterol levels in patients with lower BMI’s, which has been reported previously in this group of patients. Further studies are required to understand the basis for this exaggerated cholesterol response in patients on the ketogenic diet and its long-term clinical significance.



The Impact of the Ketogenic Diet on Cholesterol Levels in “Hyper Responders”