Overview
This conversation between Dr. Robert Lustig and Dr. Casey Means provides an in-depth explanation of cholesterol and metabolic health lab interpretation, emphasizing how to use test results to assess cardiovascular and metabolic risk, particularly focusing on triglycerides, HDL, LDL subtypes, and liver health.
Understanding the Cholesterol Panel
- Total cholesterol is not a useful standalone marker and should generally be disregarded.
- LDL cholesterol measurement includes both large buoyant (neutral) and small dense (harmful) LDL particles, but standard tests can't distinguish between them.
- Elevated LDL alone does not automatically mean a statin is needed; particle type matters.
- Triglycerides, especially when fasting, are more predictive of heart disease risk than LDL alone.
- HDL is protective; higher levels are linked to better cardiovascular health.
Key Ratios and Their Implications
- The triglyceride-to-HDL ratio is a strong indicator of heart disease and insulin resistance.
- A triglyceride-to-HDL ratio under 1.5 is ideal; over 2.5 signals increased risk (even lower cutoffs recommended for some populations).
- Triglyceride levels under 100 mg/dL are favorable, indicating lower risk of small dense LDL prevalence.
Role of Liver and Insulin Resistance
- High fasting triglycerides reflect how the liver processes dietary sugars, converting excess into VLDL, which becomes small dense LDL.
- Accumulation of liver fat (from sugar or alcohol) underlies insulin resistance and metabolic dysfunction.
- ALT (alanine transaminase) above 25 (or above 20 for African Americans) suggests liver fat accumulation, even if within standard “normal” lab ranges.
Interpreting Tests Effectively
- Always interpret lipid panels when not acutely ill and after evaluating thyroid status, as hypothyroidism can elevate triglycerides.
- Normalize ALT reference ranges should be reconsidered due to population-wide liver fat increase.
- Fasting insulin is a valuable test for metabolic health but is not routinely ordered; ideally should be under 6–10 µIU/mL.
Improving Metabolic Health
- Reducing or eliminating sugar-sweetened beverages, processed/refined carbohydrates, and alcohol helps diminish liver fat and improve lipid profiles.
- Exercise and intermittent fasting also help burn liver fat and improve metabolic parameters.
Decisions
- Disregard total cholesterol as a meaningful health indicator.
- Prioritize interpreting the triglyceride-to-HDL ratio over LDL alone when assessing cardiovascular risk.
Action Items
- TBD – Individuals: Request fasting insulin tests and review liver function tests (especially ALT) with a focus on stricter cutoffs.
- TBD – Individuals: Calculate and monitor the triglyceride-to-HDL ratio using lab results.
- TBD – Individuals: Eliminate sugary drinks, reduce processed carbs, and consider exercise/intermittent fasting for liver health.
- TBD – Physicians: Enhance lab test interpretation skills regarding lipid subtypes and metabolic risk.
Recommendations / Advice
- Focus on comprehensive interpretation of lipid profiles, considering ratios and interactions, not single values.
- Act quickly to reduce dietary sugar and processed foods for rapid improvements in triglycerides and liver health.
- Advocate for broader use of fasting insulin and proper ALT interpretation to better assess metabolic health.