Comparison of effects of long-term low-fat vs high-fat diets on blood lipid levels in overweight or obese patients: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 24139973 · doi:10.1016/j.jand.2013.07.010
What was done
Systematic review and meta-analysis of randomized controlled trials (identified through MEDLINE, EMBASE, and Cochrane Trial Register up to March 2013) comparing the long-term (≥12 months) effects of low-fat versus high-fat diets on blood lipid profiles in overweight or obese patients.
What was found
Thirty-two studies were included in the meta-analysis: - Low-fat diets produced significantly greater decreases in total cholesterol (weighted mean difference [WMD] -4.55 mg/dL [-0.12 mmol/L], 95% CI -8.03 to -1.07; P=0.01) and LDL cholesterol (WMD -3.11 mg/dL [-0.08 mmol/L], 95% CI -4.51 to -1.71; P<0.0001). - High-fat diets produced a significantly greater rise in HDL cholesterol (WMD 2.35 mg/dL [0.06 mmol/L], 95% CI 1.29 to 3.42; P<0.0001) and greater reduction in triglycerides (WMD -8.38 mg/dL [-0.095 mmol/L], 95% CI -13.50 to -3.25; P=0.001). - When restricted to hypocaloric diets, the differences between low-fat and high-fat diets on total and LDL cholesterol were abolished. - Meta-regression linked lower total cholesterol to lower saturated fat and higher polyunsaturated fat intake, higher HDL to monounsaturated fat intake, and higher triglycerides to carbohydrate intake.
Why it matters
Neither diet pattern demonstrates clear overall superiority for primary cardiovascular prevention: low-fat diets moderately favor LDL and total cholesterol, while high-fat diets favor HDL and triglycerides.
Limits
The total number of randomized participants is not stated in the abstract. Clinical cardiovascular end points (e.g., mortality, cardiovascular events) were not assessed, and the absolute differences in lipid markers were small.
Cited by
- contradicts Consuming excessive refined carbohydrates is the single biggest factor causing elevated LDL cholesterol.