(P11-017-25) Study Protocol - The Ketogenic Diet, Blood Lipids, and Vascular Health in Adults With Differing Body Mass Index

Objectives: This study protocol is for a complete-feeding clinical trial designed to investigate the differential impact of a ketogenic diet (KD) on lipid and glucose metabolism and vascular health in healthy adults with normal body mass index (BMI) versus those with obesity. The hypothesis for this study is that adults with a normal BMI will have a greater increase in low-density lipoprotein-cholesterol (LDL-C), insulin sensitivity, and lipoprotein lipase activity, and a greater decrease in flow mediated dilation (FMD) and cholesterol ester transfer protein activity compared to adults with obesity when consuming a KD.

Methods: In this non-randomized, two group parallel trial a KD will be provided for 28 days to healthy participants with normal BMI (group 1: 18.5-22 kg/m²) or obesity (group 2: 30-35 kg/m²). In both groups, participants will be generally healthy adults aged 25-45 years with an LDL-C concentration < 100 mg/dL, blood pressure < 140/90 mmHg, fasting blood glucose < 126 mg/dL and fasting triglycerides < 350 mg/dL at screening. The provided weight maintenance KD will consist of 77% of energy (%E) from fat, 5%E from net carbohydrate, and 18%E from protein. Participants will complete four clinic visits: two consecutive baseline visits and two consecutive endpoint visits after 28 days on the diet. Fasting blood samples will be obtained to assess blood lipids/lipoproteins and markers of lipoprotein and glucose metabolism. On one day at both baseline and endpoint, FMD will be conducted to assess endothelial function and dual energy x-ray absorptiometry (DEXA) will be conducted to assess body composition. Central and peripheral blood pressure as well as carotid-femoral pulse wave velocity will be measured at both time points. Between-group differences in the change from baseline for all outcomes will be assessed. LDL-C is the primary outcome.

Results: N/A

Conclusions: Reports of differential impacts of KDs on blood lipids/lipoproteins by BMI exist, although this will be the first study to directly compare the effect of a KD on change in blood lipids/lipoproteins in individuals with normal BMI and those with obesity. This study will also be the first to explore differences in lipoprotein metabolism and vascular health between these groups, providing greater insight into how cardiovascular risk may differ by BMI on a KD.

Funding Sources: Department of Nutritional Sciences