A major 2025 meta-analysis published in Clinical Nutrition reviewed 149 randomized trials and found that carbohydrate-restricted diets (including ketogenic, low-carb, and moderate-carb) provide significant metabolic benefits, particularly for glycemic control, liver function, and insulin sensitivity
This large-scale review analyzed data from over 9,100 adults across 28 countries. Researchers examined the effects of different levels of carbohydrate restriction and various macronutrient replacements (fat, protein, or both).
Key Findings:
- Significant improvements in blood glucose, insulin levels, and HOMA-IR (insulin resistance).
- Benefits to liver enzymes (especially GGT) and kidney function markers.
- Reductions in leptin (hunger hormone).
- Moderate-carb and low-carb diets often showed the most consistent benefits, while ketogenic diets produced stronger weight loss but some increases in LDL cholesterol.
- Benefits were especially pronounced in women, people with overweight/obesity, and those with Type 2 diabetes.
- Improvements occurred even in isocaloric (no calorie reduction) studies, suggesting the macronutrient shift itself drives many benefits.
The authors conclude that carbohydrate-restricted diets can be a valuable tool for metabolic health, though they recommend medical supervision, particularly for stricter ketogenic versions.