Volek 2009: Carbohydrate Restriction vs Low Fat for Metabolic Syndrome

Background

Volek JS, Phinney SD, Forsythe CE, et al. Lipids. 2009;44(4):297-309. PMID: 19082851

This randomized trial from the University of Connecticut compared carbohydrate restriction to low-fat diet for metabolic syndrome features, measuring detailed lipoprotein subfractions and inflammatory markers.

Study Design

Parameter	Details
Design	Randomized controlled trial
Population	40 adults with metabolic syndrome
Intervention	Very low-carb (<50g/d) vs low-fat (<30% cal) for 12 weeks
Key Measures	Lipoprotein subfractions, inflammatory markers, MetS criteria
Notable Feature	Hypocaloric conditions (same caloric deficit)

Key Findings

Marker	Low-Carb	Low-Fat
Triglycerides	-51%	-19%
VLDL-C	-49%	-17%
HDL-C	+13%	+1%
Small LDL particles	-29%	-5%
hsCRP	-29%	-5%
MetS resolution	55%	20%

All differences statistically significant (p<0.01).

Mechanistic Insights

Carbohydrate restriction uniquely reduces hepatic VLDL production by limiting substrate availability for de novo lipogenesis. This explains superior triglyceride reduction regardless of caloric intake. The shift to larger, buoyant LDL particles reflects improved hepatic lipid metabolism.

Clinical Implications

For metabolic syndrome, macronutrient composition matters beyond caloric restriction. Carbohydrate restriction produces greater improvements in the most atherogenic lipoproteins (small dense LDL, VLDL) even with equivalent weight loss.

Metabolic Health Perspective

This study supports using dietary carbohydrate restriction as first-line therapy for metabolic syndrome, particularly for patients with elevated TG/HDL ratio or hypertriglyceridemia.