Objective:

To compare the effects of very-low-carbohydrate ketogenic, Mediterranean, and very-low-fat plant-forward diets on weight loss and insulin sensitivity in participants with obesity, prediabetes, and hepatic steatosis.

Approach:

• Study Design: Randomized clinical trial with participants aged 18 to 55 years assigned to one of three dietary approaches.
• Dietary Composition: Very-low-carbohydrate ketogenic diet (4% energy from carbohydrates), Mediterranean diet (50%), and very-low-fat plant-forward diet (70%).
• Participant Support: All food was provided, and participants met with a dietitian weekly.
• Outcomes Measured: Primary outcomes included skeletal muscle and hepatic insulin sensitivity; secondary outcomes were exploratory.

Key Findings:

• Participants achieved about 10% weight loss across all diet groups at mean durations of 4.6, 5.4, and 5.1 months.
• Skeletal muscle insulin sensitivity increased by about 50% across all groups without significant between-group differences.
• Hepatic insulin sensitivity increased more significantly in the ketogenic diet group compared to the other diets.
• Intrahepatic triglyceride content decreased by 67% with the ketogenic diet, compared to 45% with the other diets.
• Prediabetes remission rates were 50% for ketogenic, 29% for Mediterranean, and 7% for plant-forward diets.
• 24-hour plasma glucose area under the curve decreased by 20%, 8%, and 8% in the ketogenic, Mediterranean, and plant-forward groups, respectively.
• 24-hour plasma insulin area under the curve decreased by 74%, 44%, and 27% in the ketogenic, Mediterranean, and plant-forward groups, respectively.

Limitations:

• Small sample size may limit the detection of between-group differences.
• The study could not determine the effects of less-severe carbohydrate restriction without ketosis.

Sources:

• Cell Metabolism